MapStruct 快速指南

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MapStruct - 概述

MapStruct 是一個註釋處理器，它被插入到 Java 編譯器中。插入後，它可以被 Maven、Gradle 等命令列工具用來處理對映註釋，在編譯時建立 Mapper 類。

何時需要對映？

在多層應用程式中，資料物件用於從資料庫中獲取資料，而 UI 與模型進行互動。現在，需要將獲取到資料模型中的資料對映到模型或 Java Bean，然後傳遞給 UI。請考慮以下情況。

與資料庫連線的實體類。

StudentEntity.java

@Entity
class StudentEntity {
   String id;
   String name;
}

與 UI 連線的模型類。

Student.java

class Student {
   String id;
   String name;
}

MapStruct 如何工作？

MapStruct 使用註解自動化建立 Mapper 的過程，以將資料物件與模型物件對映。它在編譯時建立 Mapper 實現，這有助於開發人員在開發過程中發現錯誤，並使其易於理解。例如 -

StudentMapper.java

@Mapper
class StudentMapper {
   StudentMapper INSTANCE = Mappers.getMapper( StudentMapper.class );   
   StudentEntity modelToEntity(Student student);
}

現在可以使用 StudentMapper.INSTANCE 輕鬆獲取對映後的物件。

StudentEntity studentEntity = StudentMapper.INSTANCE.modelToEntity(student);

MapStruct - 環境設定

MapStruct 是一個基於 Java 的庫，因此第一個要求是在您的機器上安裝 JDK。

步驟 1 - 設定 Java 開發工具包 (JDK)

您可以從 Oracle 的 Java 網站下載最新版本的 SDK - Java SE 下載。 您將在下載的檔案中找到安裝 JDK 的說明，請按照給定的說明進行安裝和配置設定。最後設定 PATH 和 JAVA_HOME 環境變數以引用包含 java 和 javac 的目錄，通常分別為 java_install_dir/bin 和 java_install_dir。

如果您正在執行 Windows 並已將 JDK 安裝在 C:\jdk-9.0.1 中，則必須將以下行放入 C:\autoexec.bat 檔案中。

set PATH=C:\jdk-11.0.11\bin;%PATH% 
set JAVA_HOME=C:\jdk-11.0.11

或者，在 Windows NT/2000/XP 上，您需要右鍵單擊“我的電腦”，選擇“屬性”→“高階”→“環境變數”。然後，您需要更新 PATH 值並單擊“確定”按鈕。

在 Unix（Solaris、Linux 等）上，如果 SDK 安裝在 /usr/local/jdk-9.0.1 中並且您使用的是 C shell，則需要將以下內容放入 .cshrc 檔案中。

setenv PATH /usr/local/jdk-11.0.11/bin:$PATH 
setenv JAVA_HOME /usr/local/jdk-11.0.11

或者，如果您使用的是整合開發環境 (IDE)，例如 Borland JBuilder、Eclipse、IntelliJ IDEA 或 Sun ONE Studio，則需要編譯並執行一個簡單的程式以確認 IDE 知道您已將 Java 安裝在何處。否則，您需要按照 IDE 文件中給出的說明進行正確的設定。

步驟 2 - 安裝 mapstruct 庫以及依賴項

從 MVNRepository 下載以下 jar 並將其用於您的類路徑。

• mapstruct-1.5.0.Beta1.jar

• mapstruct-processor-1.5.0.Beta1.jar

確保您已正確設定此目錄上的 CLASSPATH 變數，否則在執行應用程式時會遇到問題。

步驟 3 - 設定 Eclipse IDE

本教程中的所有示例均使用 Eclipse IDE 編寫。因此，我們建議您應該在您的機器上安裝最新版本的 Eclipse。

要安裝 Eclipse IDE，請從 www.eclipse.org/downloads 下載最新的 Eclipse 二進位制檔案。下載安裝後，將二進位制分發版解壓縮到方便的位置。例如，在 Windows 上的 C:\eclipse 中，或在 Linux/Unix 上的 /usr/local/eclipse 中，最後正確設定 PATH 變數。

可以透過在 Windows 機器上執行以下命令來啟動 Eclipse，或者您可以簡單地雙擊 eclipse.exe

%C:\eclipse\eclipse.exe 

可以透過在 Unix（Solaris、Linux 等）機器上執行以下命令來啟動 Eclipse -

$/usr/local/eclipse/eclipse

成功啟動後，如果一切正常，則應顯示以下結果 -

步驟 4 - 建立 Maven 專案

C:\MVN>mvn archetype:generate
-DgroupId = com.tutorialspoint.mapping 
-DartifactId = mapping 
-DarchetypeArtifactId = maven-archetype-quickstart 
-DinteractiveMode = false

它將建立一個 Maven 專案。現在更新 pom.xml 檔案，如下所示 -

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.tutorialspoint.mapping</groupId>
   <artifactId>mapping</artifactId>
   <packaging>jar</packaging>
   <version>1.0-SNAPSHOT</version>
   <name>mapping</name>
   <url>http://maven.apache.org</url>
   <dependencies>
      <dependency>
         <groupId>org.junit.jupiter</groupId>
         <artifactId>junit-jupiter-engine</artifactId>
         <version>5.0.0</version>
         <scope>test</scope>
      </dependency>
      <dependency>
         <groupId>org.mapstruct</groupId>
         <artifactId>mapstruct</artifactId>
         <version>1.5.0.Beta1</version>
      </dependency>
   </dependencies>
   <build>
      <plugins>
         <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.8.1</version>
            <configuration>
               <source>11</source> 
               <target>11</target> 
               <annotationProcessorPaths>
                  <path>
                     <groupId>org.mapstruct</groupId>
                     <artifactId>mapstruct-processor</artifactId>
                     <version>1.5.0.Beta1</version>
                  </path>
               </annotationProcessorPaths>
            </configuration>
         </plugin>
      </plugins>
   </build>
</project>

執行以下命令以更新 Maven 依賴項並構建專案。

mvn package

命令成功後。將基於 Maven 的專案作為 Maven 專案匯入 Eclipse。其餘的 Eclipse 將處理。

MapStruct - 基本對映

使用 Mapstruct 非常簡單。要建立 Mapper，請在介面上使用 **org.mapstruct.Mapper** 註解。

@Mapper
public interface StudentMapper {...}

現在在介面中建立一個轉換方法。

@Mapper
public interface StudentMapper {
   Student getModelFromEntity(StudentEntity student);
}

如果源物件和目標物件的屬性名稱相同，則這些屬性將自動對映。如果屬性名稱不同，請使用 @Mapping 註解，如下所示 -

@Mapper
public interface StudentMapper {
   @Mapping(target="className", source="classVal")
   Student getModelFromEntity(StudentEntity student);
}

此處 className 是 Student 中的屬性名稱，一個目標物件，classVal 是 StudentEntity 中的屬性名稱，一個源物件。

示例

在 Eclipse 中開啟在 環境設定 章節中建立的專案對映。

使用以下程式碼建立 Student.java -

Student.java

package com.tutorialspoint.model;

public class Student {
   private int id;
   private String name;
   private String className;

   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
   public String getClassName() {
      return className;
   }
   public void setClassName(String className) {
      this.className = className;
   }
}

使用以下程式碼建立 Student.java -

StudentEntity.java

package com.tutorialspoint.entity;

public class StudentEntity {
   private int id;
   private String name;
   private String classVal;
   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
   public String getClassVal() {
      return classVal;
   }
   public void setClassVal(String classVal) {
      this.classVal = classVal;
   }
}

使用以下程式碼建立 StudentMapper.java -

StudentMapper.java

package com.tutorialspoint.mapper;

import org.mapstruct.Mapper;
import org.mapstruct.Mapping;

import com.tutorialspoint.entity.StudentEntity;
import com.tutorialspoint.model.Student;

@Mapper
public interface StudentMapper {

   @Mapping(target="className", source="classVal")
   Student getModelFromEntity(StudentEntity student);

   @Mapping(target="classVal", source="className")
   StudentEntity getEntityFromModel(Student student);
}

使用以下程式碼建立 StudentMapperTest.java -

StudentMapperTest.java

package com.tutorialspoint.mapping;

import static org.junit.jupiter.api.Assertions.assertEquals;

import org.junit.jupiter.api.Test;
import org.mapstruct.factory.Mappers;

import com.tutorialspoint.entity.StudentEntity;
import com.tutorialspoint.mapper.StudentMapper;
import com.tutorialspoint.model.Student;

public class StudentMapperTest {

   private StudentMapper studentMapper
      = Mappers.getMapper(StudentMapper.class);

   @Test
   public void testEntityToModel() {
      StudentEntity entity = new StudentEntity();
      entity.setClassVal("X");
      entity.setName("John");
      entity.setId(1);

      Student model = studentMapper.getModelFromEntity(entity);

      assertEquals(entity.getClassVal(), model.getClassName());
      assertEquals(entity.getName(), model.getName());
      assertEquals(entity.getId(), model.getId());
   }

   @Test
   public void testModelToEntity() {
      Student model = new Student();
      model.setId(1);
      model.setName("John");
      model.setClassName("X");

      StudentEntity entity = studentMapper.getEntityFromModel(model);

      assertEquals(entity.getClassVal(), model.getClassName());
      assertEquals(entity.getName(), model.getName());
      assertEquals(entity.getId(), model.getId());
   }
}

執行以下命令測試對映。

mvn clean test

命令成功後。驗證輸出。

mvn clean test
[INFO] Scanning for projects...
...
[INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ mapping ---
[INFO] Surefire report directory: \mvn\mapping\target\surefire-reports

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running com.tutorialspoint.mapping.StudentMapperTest
Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.004 sec
...

MapStruct - 自定義對映

我們還可以將自定義方法新增到使用 **org.mapstruct.Mapper** 註解建立的 Mapper 中。我們也可以建立抽象類而不是介面。Mapstruct 自動建立相應的 Mapper 類。

現在在介面中建立一個預設轉換方法。

@Mapper
public interface StudentMapper {
   default Student getModelFromEntity(StudentEntity studentEntity){
      Student student = new Student();
      student.setId(studentEntity.getId());
      student.setName(studentEntity.getName());
      student.setClassName(studentEntity.getClassVal());
      return student;
   }
}

以類似的方式，我們也可以建立抽象類以及 Mapper。

@Mapper
public absgract class StudentMapper {
   Student getModelFromEntity(StudentEntity studentEntity){
      Student student = new Student();
      student.setId(studentEntity.getId());
      student.setName(studentEntity.getName());
      student.setClassName(studentEntity.getClassVal());
      return student;
   }
}

示例

在 Eclipse 中開啟在 環境設定 章節中建立的專案 mediaPlayer。

使用以下程式碼建立 Student.java -

Student.java

package com.tutorialspoint.model;

public class Student {
   private int id;
   private String name;
   private String className;

   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
   public String getClassName() {
      return className;
   }
   public void setClassName(String className) {
      this.className = className;
   }
}

使用以下程式碼建立 Student.java -

StudentEntity.java

package com.tutorialspoint.entity;

public class StudentEntity {
   private int id;
   private String name;
   private String classVal;
   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
   public String getClassVal() {
      return classVal;
   }
   public void setClassVal(String classVal) {
      this.classVal = classVal;
   }
}

使用以下程式碼建立 StudentMapper.java -

StudentMapper.java

package com.tutorialspoint.mapper;

import org.mapstruct.Mapper;
import org.mapstruct.Mapping;

import com.tutorialspoint.entity.StudentEntity;
import com.tutorialspoint.model.Student;

@Mapper
public interface StudentMapper {

   default Student getModelFromEntity(StudentEntity studentEntity){
      Student student = new Student();
      student.setId(studentEntity.getId());
      student.setName(studentEntity.getName());
      student.setClassName(studentEntity.getClassVal());
      return student;
   }

   @Mapping(target="classVal", source="className")
   StudentEntity getEntityFromModel(Student student);
}

使用以下程式碼建立 StudentMapperTest.java -

StudentMapperTest.java

package com.tutorialspoint.mapping;

import static org.junit.jupiter.api.Assertions.assertEquals;

import org.junit.jupiter.api.Test;
import org.mapstruct.factory.Mappers;

import com.tutorialspoint.entity.StudentEntity;
import com.tutorialspoint.mapper.StudentMapper;
import com.tutorialspoint.model.Student;

public class StudentMapperTest {

   private StudentMapper studentMapper
      = Mappers.getMapper(StudentMapper.class);

   @Test
   public void testEntityToModel() {
      StudentEntity entity = new StudentEntity();
      entity.setClassVal("X");
      entity.setName("John");
      entity.setId(1);

      Student model = studentMapper.getModelFromEntity(entity);

      assertEquals(entity.getClassVal(), model.getClassName());
      assertEquals(entity.getName(), model.getName());
      assertEquals(entity.getId(), model.getId());
   }

   @Test
   public void testModelToEntity() {
      Student model = new Student();
      model.setId(1);
      model.setName("John");
      model.setClassName("X");

      StudentEntity entity = studentMapper.getEntityFromModel(model);

      assertEquals(entity.getClassVal(), model.getClassName());
      assertEquals(entity.getName(), model.getName());
      assertEquals(entity.getId(), model.getId());
   }
}

執行以下命令測試對映。

mvn clean test

命令成功後。驗證輸出。

mvn clean test
[INFO] Scanning for projects...
...
[INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ mapping ---
[INFO] Surefire report directory: \mvn\mapping\target\surefire-reports

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running com.tutorialspoint.mapping.StudentMapperTest
Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.004 sec
...

MapStruct - 多物件對映

我們還可以新增對映多個物件的功能。例如，我們想使用 Student 和 Address 物件獲取 DeliveryAddress 物件。

現在建立一個 Mapper 介面，它可以將兩個物件對映到一個物件。

@Mapper
public interface DeliveryAddressMapper {
   @Mapping(source = "student.name", target = "name")
   @Mapping(source = "address.houseNo", target = "houseNumber")
   DeliveryAddress getDeliveryAddress(StudentEntity student, AddressEntity address);   
}

示例

在 Eclipse 中開啟在 自定義對映 章節中更新的專案對映。

使用以下程式碼建立 DeliveryAddress.java -

DeliveryAddress.java

package com.tutorialspoint.model;

public class DeliveryAddress {	
	private String name;
	private int houseNumber;
	private String city;
	private String state;
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getHouseNumber() {
		return houseNumber;
	}
	public void setHouseNumber(int houseNumber) {
		this.houseNumber = houseNumber;
	}
	public String getCity() {
		return city;
	}
	public void setCity(String city) {
		this.city = city;
	}
	public String getState() {
		return state;
	}
	public void setState(String state) {
		this.state = state;
	}
}

使用以下程式碼建立 AddressEntity.java -

AddressEntity.java

package com.tutorialspoint.entity;

public class AddressEntity {
	private int houseNo;
	private String city;
	private String state;
	public int getHouseNo() {
		return houseNo;
	}
	public void setHouseNo(int houseNo) {
		this.houseNo = houseNo;
	}
	public String getCity() {
		return city;
	}
	public void setCity(String city) {
		this.city = city;
	}
	public String getState() {
		return state;
	}
	public void setState(String state) {
		this.state = state;
	}
}

使用以下程式碼建立 DeliveryAddressMapper.java -

DeliveryAddressMapper.java

package com.tutorialspoint.mapper;

import org.mapstruct.Mapper;
import org.mapstruct.Mapping;

import com.tutorialspoint.entity.AddressEntity;
import com.tutorialspoint.entity.StudentEntity;
import com.tutorialspoint.model.DeliveryAddress;

@Mapper
public interface DeliveryAddressMapper {
   @Mapping(source = "student.name", target = "name")
   @Mapping(source = "address.houseNo", target = "houseNumber")
   DeliveryAddress getDeliveryAddress(StudentEntity student, AddressEntity address);   
}

使用以下程式碼建立 DeliveryAddressMapperTest.java -

DeliveryAddressMapperTest.java

package com.tutorialspoint.mapping;

import static org.junit.jupiter.api.Assertions.assertEquals;

import org.junit.jupiter.api.Test;
import org.mapstruct.factory.Mappers;

import com.tutorialspoint.entity.AddressEntity;
import com.tutorialspoint.entity.StudentEntity;
import com.tutorialspoint.mapper.DeliveryAddressMapper;
import com.tutorialspoint.model.DeliveryAddress;

public class DeliveryAddressMapperTest {

   private DeliveryAddressMapper deliveryAddressMapper
      = Mappers.getMapper(DeliveryAddressMapper.class);

   @Test
   public void testEntityToModel() {
      StudentEntity student = new StudentEntity();
      student.setClassVal("X");
      student.setName("John");
      student.setId(1);

      AddressEntity address = new AddressEntity();
      address.setCity("Y");
      address.setState("Z");
      address.setHouseNo(1);

      DeliveryAddress deliveryAddress = deliveryAddressMapper.getDeliveryAddress(student, address);

      assertEquals(deliveryAddress.getName(), student.getName());
      assertEquals(deliveryAddress.getCity(), address.getCity());
      assertEquals(deliveryAddress.getState(), address.getState());
      assertEquals(deliveryAddress.getHouseNumber(), address.getHouseNo());

   }
}	

執行以下命令測試對映。

mvn clean test

命令成功後。驗證輸出。

mvn clean test
[INFO] Scanning for projects...
...
[INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ mapping ---
[INFO] Surefire report directory: \mvn\mapping\target\surefire-reports

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running com.tutorialspoint.mapping.DeliveryAddressMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.011 sec
Running com.tutorialspoint.mapping.StudentMapperTest
Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.001 sec

Results :

Tests run: 3, Failures: 0, Errors: 0, Skipped: 0
...

MapStruct - 巢狀 Bean 對映

MapStruct 無縫處理巢狀對映。例如，具有 Subject 作為巢狀 Bean 的 Student。

現在建立一個 Mapper 介面，它可以對映巢狀物件。

@Mapper
public interface StudentMapper {
   @Mapping(target="className", source="classVal")
   @Mapping(target="subject", source="subject.name")
   Student getModelFromEntity(StudentEntity studentEntity);
	
   @Mapping(target="classVal", source="className")
   @Mapping(target="subject.name", source="subject")
   StudentEntity getEntityFromModel(Student student);
}

示例

在 Eclipse 中開啟在 多物件對映 章節中更新的專案對映。

使用以下程式碼建立 SubjectEntity.java -

SubjectEntity.java

package com.tutorialspoint.entity;

public class SubjectEntity {
   private String name;
   public String getName() {
      return name;
   }

   public void setName(String name) {
      this.name = name;
   }	
}

使用以下程式碼更新 StudentEntity.java -

StudentEntity.java

package com.tutorialspoint.entity;

public class StudentEntity {
   private int id;
   private String name;
   private String classVal;
   private SubjectEntity subject;
   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
   public String getClassVal() {
      return classVal;
   }
   public void setClassVal(String classVal) {
      this.classVal = classVal;
   }
   public SubjectEntity getSubject() {
      return subject;
   }
   public void setSubject(SubjectEntity subject) {
      this.subject = subject;
   }
}

使用以下程式碼更新 Student.java -

Student.java

package com.tutorialspoint.model;

public class Student {
   private int id;
   private String name;
   private String className;
   private String subject;
   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
   public String getClassName() {
      return className;
   }
   public void setClassName(String className) {
      this.className = className;
   }
   public String getSubject() {
      return subject;
   }
   public void setSubject(String subject) {
      this.subject = subject;
   }
}

使用以下程式碼更新 StudentMapper.java -

StudentMapper.java

package com.tutorialspoint.mapper;

import org.mapstruct.Mapper;
import org.mapstruct.Mapping;

import com.tutorialspoint.entity.StudentEntity;
import com.tutorialspoint.model.Student;

@Mapper
public interface StudentMapper {

   @Mapping(target="className", source="classVal")
   @Mapping(target="subject", source="subject.name")
   Student getModelFromEntity(StudentEntity studentEntity);

   @Mapping(target="classVal", source="className")
   @Mapping(target="subject.name", source="subject")
   StudentEntity getEntityFromModel(Student student);
}

使用以下程式碼更新 StudentMapperTest.java -

StudentMapperTest.java

package com.tutorialspoint.mapping;

import static org.junit.jupiter.api.Assertions.assertEquals;

import org.junit.jupiter.api.Test;
import org.mapstruct.factory.Mappers;

import com.tutorialspoint.entity.StudentEntity;
import com.tutorialspoint.entity.SubjectEntity;
import com.tutorialspoint.mapper.StudentMapper;
import com.tutorialspoint.model.Student;

public class StudentMapperTest {
   private StudentMapper studentMapper
      = Mappers.getMapper(StudentMapper.class);

   @Test
   public void testEntityToModel() {
      StudentEntity entity = new StudentEntity();
      entity.setClassVal("X");
      entity.setName("John");
      entity.setId(1);

      SubjectEntity subject = new SubjectEntity();
      subject.setName("Computer");
      entity.setSubject(subject);

      Student model = studentMapper.getModelFromEntity(entity);

      assertEquals(entity.getClassVal(), model.getClassName());
      assertEquals(entity.getName(), model.getName());
      assertEquals(entity.getId(), model.getId());
      assertEquals(entity.getSubject().getName(), model.getSubject());        
   }

   @Test
   public void testModelToEntity() {
      Student model = new Student();
      model.setId(1);
      model.setName("John");
      model.setClassName("X");
      model.setSubject("Science");
      StudentEntity entity = studentMapper.getEntityFromModel(model);

      assertEquals(entity.getClassVal(), model.getClassName());
      assertEquals(entity.getName(), model.getName());
      assertEquals(entity.getId(), model.getId());
      assertEquals(entity.getSubject().getName(), model.getSubject());
   }
}

執行以下命令測試對映。

mvn clean test

命令成功後。驗證輸出。

mvn clean test
[INFO] Scanning for projects...
...
[INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ mapping ---
[INFO] Surefire report directory: \mvn\mapping\target\surefire-reports

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running com.tutorialspoint.mapping.DeliveryAddressMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.005 sec
Running com.tutorialspoint.mapping.StudentMapperTest
Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.002 sec

Results :

Tests run: 3, Failures: 0, Errors: 0, Skipped: 0
...

MapStruct - 直接欄位對映

MapStruct 輕鬆處理直接欄位對映。例如，Student 具有 section 作為私有屬性，而 StudentEntity 具有 section 作為公共屬性。要進行 getter/setter 對映，屬性必須是公共的。如果是 public final，則只有 getter 方法可用於對映。

現在建立一個 Mapper 介面。我們將使用 @InheritInverseConfiguration 註解來複制反向配置。

@Mapper
public interface StudentMapper {
   @Mapping(target="className", source="classVal")
   @Mapping(target="subject", source="subject.name")
   Student getModelFromEntity(StudentEntity studentEntity);
	
   @InheritInverseConfiguration
   StudentEntity getEntityFromModel(Student student);
}

示例

在 Eclipse 中開啟在 巢狀物件對映 章節中更新的專案對映。

使用以下程式碼更新 StudentEntity.java -

StudentEntity.java

package com.tutorialspoint.entity;

public class StudentEntity {
   private int id;
   private String name;
   private String classVal;
   private SubjectEntity subject;
   public String section;
   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
   public String getClassVal() {
      return classVal;
   }
   public void setClassVal(String classVal) {
      this.classVal = classVal;
   }
   public SubjectEntity getSubject() {
      return subject;
   }
   public void setSubject(SubjectEntity subject) {
      this.subject = subject;
   }
}

使用以下程式碼更新 Student.java -

Student.java

package com.tutorialspoint.model;

public class Student {
   private int id;
   private String name;
   private String className;
   private String subject;
   private String section;
   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
   public String getClassName() {
      return className;
   }
   public void setClassName(String className) {
      this.className = className;
   }
   public String getSubject() {
      return subject;
   }
   public void setSubject(String subject) {
      this.subject = subject;
   }
   public String getSection() {
      return section;
   }
   public void setSection(String section) {
      this.section = section;
   }
}

使用以下程式碼更新 StudentMapper.java -

StudentMapper.java

package com.tutorialspoint.mapper;

import org.mapstruct.InheritInverseConfiguration;
import org.mapstruct.Mapper;
import org.mapstruct.Mapping;

import com.tutorialspoint.entity.StudentEntity;
import com.tutorialspoint.model.Student;

@Mapper
public interface StudentMapper {

   @Mapping(target="className", source="classVal")
   @Mapping(target="subject", source="subject.name")
   Student getModelFromEntity(StudentEntity studentEntity);

   @InheritInverseConfiguration
   StudentEntity getEntityFromModel(Student student);
}

使用以下程式碼更新 StudentMapperTest.java -

StudentMapperTest.java

package com.tutorialspoint.mapping;

import static org.junit.jupiter.api.Assertions.assertEquals;

import org.junit.jupiter.api.Test;
import org.mapstruct.factory.Mappers;

import com.tutorialspoint.entity.StudentEntity;
import com.tutorialspoint.entity.SubjectEntity;
import com.tutorialspoint.mapper.StudentMapper;
import com.tutorialspoint.model.Student;

public class StudentMapperTest {
   private StudentMapper studentMapper
      = Mappers.getMapper(StudentMapper.class);

   @Test
   public void testEntityToModel() {
      StudentEntity entity = new StudentEntity();
      entity.setClassVal("X");
      entity.setName("John");
      entity.setId(1);
      entity.section = "A";
      SubjectEntity subject = new SubjectEntity();
      subject.setName("Computer");
      entity.setSubject(subject);

      Student model = studentMapper.getModelFromEntity(entity);

      assertEquals(entity.getClassVal(), model.getClassName());
      assertEquals(entity.getName(), model.getName());
      assertEquals(entity.getId(), model.getId());
      assertEquals(entity.getSubject().getName(), model.getSubject());
      assertEquals(entity.section, model.getSection());	  
   }

   @Test
   public void testModelToEntity() {
      Student model = new Student();
      model.setId(1);
      model.setName("John");
      model.setClassName("X");
      model.setSubject("Science");
      model.setSection("A");
      StudentEntity entity = studentMapper.getEntityFromModel(model);

      assertEquals(entity.getClassVal(), model.getClassName());
      assertEquals(entity.getName(), model.getName());
      assertEquals(entity.getId(), model.getId());
      assertEquals(entity.getSubject().getName(), model.getSubject());
      assertEquals(entity.section, model.getSection());
   }
}

執行以下命令測試對映。

mvn clean test

命令成功後。驗證輸出。

mvn clean test
[INFO] Scanning for projects...
...
[INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ mapping ---
[INFO] Surefire report directory: \mvn\mapping\target\surefire-reports

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running com.tutorialspoint.mapping.DeliveryAddressMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.005 sec
Running com.tutorialspoint.mapping.StudentMapperTest
Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.002 sec

Results :

Tests run: 3, Failures: 0, Errors: 0, Skipped: 0
...

MapStruct - 使用 Builder

MapStruct 允許使用 Builder。我們可以使用 Builder 框架或使用我們自定義的 Builder。在下面的示例中，我們使用自定義 Builder。

示例

在 Eclipse 中開啟在 直接欄位對映 章節中更新的專案對映。

使用以下程式碼更新 Student.java -

Student.java

package com.tutorialspoint.model;

public class Student {
   private final String name;
   private final int id;

   protected Student(Student.Builder builder) {
      this.name = builder.name;
      this.id = builder.id;
   }
   public static Student.Builder builder() {
      return new Student.Builder();
   }
   public static class Builder {
      private String name;
      private int id;
      public Builder name(String name) {
         this.name = name;
         return this;
      }
      public Builder id(int id) {
         this.id = id;
         return this;
      }
      public Student create() {
         return new Student( this );
      }
   }
   public String getName() {
      return name;
   }
   public int getId() {
      return id;
   }
}

使用以下程式碼更新 StudentMapper.java -

StudentMapper.java

package com.tutorialspoint.mapper;

import org.mapstruct.Mapper;
import org.mapstruct.Mapping;
import com.tutorialspoint.entity.StudentEntity;
import com.tutorialspoint.model.Student;

@Mapper
public interface StudentMapper {
   Student getModelFromEntity(StudentEntity studentEntity);
   @Mapping(target="id", source="id")
   @Mapping(target="name", source="name")
   StudentEntity getEntityFromModel(Student student);
}

使用以下程式碼更新 StudentMapperTest.java -

StudentMapperTest.java

package com.tutorialspoint.mapping;

import static org.junit.jupiter.api.Assertions.assertEquals;
import org.junit.jupiter.api.Test;
import org.mapstruct.factory.Mappers;
import com.tutorialspoint.entity.StudentEntity;
import com.tutorialspoint.entity.SubjectEntity;
import com.tutorialspoint.mapper.StudentMapper;
import com.tutorialspoint.model.Student;

public class StudentMapperTest {
   private StudentMapper studentMapper = Mappers.getMapper(StudentMapper.class);
   
   @Test
   public void testEntityToModel() {
      StudentEntity entity = new StudentEntity();
      entity.setName("John");
      entity.setId(1);
      Student model = studentMapper.getModelFromEntity(entity);
      assertEquals(entity.getName(), model.getName());
      assertEquals(entity.getId(), model.getId());
   }
   @Test
   public void testModelToEntity() {
      Student.Builder builder = Student.builder().id(1).name("John");
      Student model = builder.create();
      StudentEntity entity = studentMapper.getEntityFromModel(model);
      assertEquals(entity.getName(), model.getName());
      assertEquals(entity.getId(), model.getId());
   }
}

執行以下命令測試對映。

mvn clean test

輸出

命令成功後。驗證輸出。

mvn clean test
[INFO] Scanning for projects...
...
[INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ mapping ---
[INFO] Surefire report directory: \mvn\mapping\target\surefire-reports

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running com.tutorialspoint.mapping.DeliveryAddressMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.005 sec
Running com.tutorialspoint.mapping.StudentMapperTest
Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.002 sec

Results :

Tests run: 3, Failures: 0, Errors: 0, Skipped: 0
...

MapStruct - 隱式型別轉換

MapStruct 在大多數情況下自動處理型別轉換。例如，int 到 Long 或 String 的轉換。轉換也處理空值。以下是一些重要的自動轉換。

• 在基本型別和對應的包裝類之間。

• 在基本型別和 String 之間。

• 在列舉型別和 String 之間。

• 在 BigInt、BigDecimal 和 String 之間。

• 在 Calendar/Date 和 XMLGregorianCalendar 之間。

• 在 XMLGregorianCalendar 和 String 之間。

• 在 Jodas 日期型別和 String 之間。

示例

在 Eclipse 中開啟在 使用 Builder 對映 章節中更新的專案對映。

使用以下程式碼更新 StudentEntity.java -

StudentEntity.java

package com.tutorialspoint.entity;

public class StudentEntity {
   private String id;
   private String name;
   private String classVal;
   private SubjectEntity subject;
   public String section;
   public String getId() {
      return id;
   }
   public void setId(String id) {
      this.id = id;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
   public String getClassVal() {
      return classVal;
   }
   public void setClassVal(String classVal) {
      this.classVal = classVal;
   }
   public SubjectEntity getSubject() {
      return subject;
   }
   public void setSubject(SubjectEntity subject) {
      this.subject = subject;
   }
}

Student.java 保持不變，程式碼如下 -

Student.java

package com.tutorialspoint.model;

public class Student {
   private final String name;
   private final int id;

   protected Student(Student.Builder builder) {
      this.name = builder.name;
      this.id = builder.id;
   }

   public static Student.Builder builder() {
      return new Student.Builder();
   }

   public static class Builder {
      private String name;
      private int id;

      public Builder name(String name) {
         this.name = name;
         return this;
      }

      public Builder id(int id) {
         this.id = id;
         return this;
      }

      public Student create() {
         return new Student( this );
      }
   }

   public String getName() {
      return name;
   }

   public int getId() {
      ret+urn id;
   }
}

使用以下程式碼更新 DeliveryAddressMapperTest.java -

DeliveryAddressMapperTest.java

package com.tutorialspoint.mapping;

import static org.junit.jupiter.api.Assertions.assertEquals;

import org.junit.jupiter.api.Test;
import org.mapstruct.factory.Mappers;

import com.tutorialspoint.entity.AddressEntity;
import com.tutorialspoint.entity.StudentEntity;
import com.tutorialspoint.mapper.DeliveryAddressMapper;
import com.tutorialspoint.model.DeliveryAddress;

public class DeliveryAddressMapperTest {

   private DeliveryAddressMapper deliveryAddressMapper
      = Mappers.getMapper(DeliveryAddressMapper.class);

   @Test
   public void testEntityToModel() {
      StudentEntity student = new StudentEntity();
      student.setClassVal("X");
      student.setName("John");
      student.setId("1");

      AddressEntity address = new AddressEntity();
      address.setCity("Y");
      address.setState("Z");
      address.setHouseNo(1);

      DeliveryAddress deliveryAddress = deliveryAddressMapper.getDeliveryAddress(student, address);

      assertEquals(deliveryAddress.getName(), student.getName());
      assertEquals(deliveryAddress.getCity(), address.getCity());
      assertEquals(deliveryAddress.getState(), address.getState());
      assertEquals(deliveryAddress.getHouseNumber(), address.getHouseNo());

   }
}

使用以下程式碼更新 StudentMapperTest.java -

StudentMapperTest.java

package com.tutorialspoint.mapping;

import static org.junit.jupiter.api.Assertions.assertEquals;

import org.junit.jupiter.api.Test;
import org.mapstruct.factory.Mappers;

import com.tutorialspoint.entity.StudentEntity;
import com.tutorialspoint.entity.SubjectEntity;
import com.tutorialspoint.mapper.StudentMapper;
import com.tutorialspoint.model.Student;

public class StudentMapperTest {

   private StudentMapper studentMapper
      = Mappers.getMapper(StudentMapper.class);

   @Test
   public void testEntityToModel() {
      StudentEntity entity = new StudentEntity();
      entity.setName("John");
      entity.setId("1");

      Student model = studentMapper.getModelFromEntity(entity);
      assertEquals(entity.getName(), model.getName());
      assertEquals(Integer.parseInt(entity.getId()), model.getId());
   }

   @Test
   public void testModelToEntity() {
      Student.Builder builder = Student.builder().id(1).name("John");
      Student model = builder.create();
      StudentEntity entity = studentMapper.getEntityFromModel(model);

      assertEquals(entity.getName(), model.getName());
      assertEquals(Integer.parseInt(entity.getId()), model.getId());
   }
}

執行以下命令測試對映。

mvn clean test

命令成功後。驗證輸出。

mvn clean test
[INFO] Scanning for projects...
...
[INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ mapping ---
[INFO] Surefire report directory: \mvn\mapping\target\surefire-reports

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running com.tutorialspoint.mapping.DeliveryAddressMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.005 sec
Running com.tutorialspoint.mapping.StudentMapperTest
Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.002 sec

Results :

Tests run: 3, Failures: 0, Errors: 0, Skipped: 0
...

MapStruct - 使用 numberFormat

MapStruct 無縫處理將數字轉換為所需格式的 String。我們可以在 @Mapping 註解期間將所需的格式作為 numberFormat 傳遞。例如，考慮一種情況，其中以數字儲存的金額需要以貨幣格式顯示。

• **源** - 實體的價格為 350。

• **目標** - 模型顯示價格為 $350.00。

• **numberFormat** - 使用格式 $#.00

示例

在 Eclipse 中開啟在 對映隱式型別轉換 章節中更新的專案對映。

使用以下程式碼建立 CarEntity.java -

CarEntity.java

package com.tutorialspoint.entity;

public class CarEntity {
   private int id;
   private double price;
   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
   public double getPrice() {
      return price;
   }
   public void setPrice(double price) {
      this.price = price;
   }
}

使用以下程式碼建立 Car.java -

Car.java

package com.tutorialspoint.model;

public class Car {
   private int id;
   private String price;
   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
   public String getPrice() {
      return price;
   }
   public void setPrice(String price) {
      this.price = price;
   }
}

使用以下程式碼建立 CarMapper.java -

CarMapper.java

package com.tutorialspoint.mapper;

import org.mapstruct.Mapper;
import org.mapstruct.Mapping;

import com.tutorialspoint.entity.CarEntity;
import com.tutorialspoint.model.Car;

@Mapper
public interface CarMapper {
   @Mapping(source = "price", target = "price", numberFormat = "$#.00")
   Car getModelFromEntity(CarEntity carEntity);
}

使用以下程式碼建立 CarMapperTest.java -

CarMapperTest.java

package com.tutorialspoint.mapping;

import static org.junit.jupiter.api.Assertions.assertEquals;

import org.junit.jupiter.api.Test;
import org.mapstruct.factory.Mappers;

import com.tutorialspoint.entity.CarEntity;
import com.tutorialspoint.mapper.CarMapper;
import com.tutorialspoint.model.Car;

public class CarMapperTest {
   private CarMapper carMapper
      = Mappers.getMapper(CarMapper.class);

   @Test
   public void testEntityToModel() {
      CarEntity entity = new CarEntity();
      entity.setPrice(345000);
      entity.setId(1);

      Car model = carMapper.getModelFromEntity(entity);
      assertEquals(model.getPrice(), "$345000.00");
      assertEquals(entity.getId(), model.getId());
   }
}

執行以下命令測試對映。

mvn clean test

命令成功後。驗證輸出。

mvn clean test
[INFO] Scanning for projects...
...
[INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ mapping ---
[INFO] Surefire report directory: \mvn\mapping\target\surefire-reports

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running com.tutorialspoint.mapping.CarMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.035 sec
Running com.tutorialspoint.mapping.DeliveryAddressMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0 sec
Running com.tutorialspoint.mapping.StudentMapperTest
Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.001 sec

Results :

Tests run: 4, Failures: 0, Errors: 0, Skipped: 0
...

MapStruct - 使用 dateFormat

MapStruct 無縫處理將日期轉換為所需格式的 String。我們可以在 @Mapping 註解期間將所需的格式作為 dateFormat 傳遞。例如，考慮一種情況，其中以數字儲存的日期需要以特定格式顯示。

• **源** - 實體的日期為 GregorianCalendar(2015, 3, 5)。

• **目標** - 模型顯示日期為 05.04.2015。

• **dateFormat** - 使用格式 dd.MM.yyyy

示例

在 Eclipse 中開啟專案對映，該對映在使用 numberFormat 對映章節中進行了更新。

使用以下程式碼更新 CarEntity.java −

CarEntity.java

package com.tutorialspoint.entity;
import java.util.GregorianCalendar;

public class CarEntity {
   private int id;
   private double price;
   private GregorianCalendar manufacturingDate;
   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
   public double getPrice() {
      return price;
   }
   public void setPrice(double price) {
      this.price = price;
   }
   public GregorianCalendar getManufacturingDate() {
      return manufacturingDate;
   }
   public void setManufacturingDate(GregorianCalendar manufacturingDate) {
      this.manufacturingDate = manufacturingDate;
   }
}

使用以下程式碼更新 Car.java −

Car.java

package com.tutorialspoint.model;

public class Car {
   private int id;
   private String price;
   private String manufacturingDate;
   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
   public String getPrice() {
      return price;
   }
   public void setPrice(String price) {
      this.price = price;
   }
   public String getManufacturingDate() {
      return manufacturingDate;
   }
   public void setManufacturingDate(String manufacturingDate) {
      this.manufacturingDate = manufacturingDate;
   }
}

使用以下程式碼更新 CarMapper.java −

CarMapper.java

package com.tutorialspoint.mapper;

import org.mapstruct.Mapper;
import org.mapstruct.Mapping;

import com.tutorialspoint.entity.CarEntity;
import com.tutorialspoint.model.Car;

@Mapper
public interface CarMapper {
   @Mapping(source = "price", target = "price", numberFormat = "$#.00")
   @Mapping(source = "manufacturingDate", target = "manufacturingDate", dateFormat = "dd.MM.yyyy")
   Car getModelFromEntity(CarEntity carEntity);
}

使用以下程式碼更新 CarMapperTest.java −

CarMapperTest.java

package com.tutorialspoint.mapping;

import static org.junit.jupiter.api.Assertions.assertEquals;
import java.util.GregorianCalendar;
import org.junit.jupiter.api.Test;
import org.mapstruct.factory.Mappers;

import com.tutorialspoint.entity.CarEntity;
import com.tutorialspoint.mapper.CarMapper;
import com.tutorialspoint.model.Car;

public class CarMapperTest {
   private CarMapper carMapper
      = Mappers.getMapper(CarMapper.class);

   @Test
   public void testEntityToModel() {
      CarEntity entity = new CarEntity();
      entity.setPrice(345000);
      entity.setId(1);
      entity.setManufacturingDate(new GregorianCalendar(2015, 3, 5));
      Car model = carMapper.getModelFromEntity(entity);
      assertEquals(model.getPrice(), "$345000.00");
      assertEquals(entity.getId(), model.getId());
      assertEquals("05.04.2015", model.getManufacturingDate());
   }
}

執行以下命令測試對映。

mvn clean test

命令成功後。驗證輸出。

mvn clean test
[INFO] Scanning for projects...
...
[INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ mapping ---
[INFO] Surefire report directory: \mvn\mapping\target\surefire-reports

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running com.tutorialspoint.mapping.CarMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.035 sec
Running com.tutorialspoint.mapping.DeliveryAddressMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0 sec
Running com.tutorialspoint.mapping.StudentMapperTest
Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.001 sec

Results :

Tests run: 4, Failures: 0, Errors: 0, Skipped: 0
...

MapStruct - 使用表示式

MapStruct 允許為自定義邏輯呼叫轉換方法。我們可以使用表示式來實現相同的功能，在表示式中我們可以傳遞任何 Java 物件並呼叫其方法進行轉換。

語法

@Mapping(target = "target-property", 
	expression = "java(target-method())")

這裡

• 目標屬性 - 我們正在進行對映的屬性。

• 表示式 - 對映器將呼叫表示式中編寫的 Java 方法。

• 目標方法 - 目標方法是要呼叫的方法。如果方法存在於不同的類中，請使用 new 類名.目標方法()

示例

在 Eclipse 中開啟專案對映，該對映在使用 dateFormat 對映章節中進行了更新。

使用以下程式碼更新 CarEntity.java −

CarEntity.java

package com.tutorialspoint.entity;
import java.util.GregorianCalendar;

public class CarEntity {
   private int id;
   private double price;
   private GregorianCalendar manufacturingDate;
   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
   public double getPrice() {
      return price;
   }
   public void setPrice(double price) {
      this.price = price;
   }
   public GregorianCalendar getManufacturingDate() {
      return manufacturingDate;
   }
   public void setManufacturingDate(GregorianCalendar manufacturingDate) {
      this.manufacturingDate = manufacturingDate;
   }
}

使用以下程式碼更新 Car.java −

Car.java

package com.tutorialspoint.model;

public class Car {
   private int id;
   private String price;
   private String manufacturingDate;
   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
   public String getPrice() {
      return price;
   }
   public void setPrice(String price) {
      this.price = price;
   }
   public String getManufacturingDate() {
      return manufacturingDate;
   }
   public void setManufacturingDate(String manufacturingDate) {
      this.manufacturingDate = manufacturingDate;
   }
}

使用以下程式碼更新 CarMapper.java −

CarMapper.java

package com.tutorialspoint.mapper;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.GregorianCalendar;

import org.mapstruct.Mapper;
import org.mapstruct.Mapping;

import com.tutorialspoint.entity.CarEntity;
import com.tutorialspoint.model.Car;

@Mapper
public interface CarMapper {
   @Mapping(source = "price", target = "price", numberFormat = "$#.00")
   @Mapping(target = "manufacturingDate", 
      expression = "java(getManufacturingDate(carEntity.getManufacturingDate()))")
   Car getModelFromEntity(CarEntity carEntity);

   default String getManufacturingDate(GregorianCalendar manufacturingDate) {
      Date d = manufacturingDate.getTime();
      SimpleDateFormat sdf = new SimpleDateFormat( "dd.MM.yyyy" );
      return sdf.format( d );
   }
}

使用以下程式碼更新 CarMapperTest.java −

CarMapperTest.java

package com.tutorialspoint.mapping;

import static org.junit.jupiter.api.Assertions.assertEquals;
import java.util.GregorianCalendar;
import org.junit.jupiter.api.Test;
import org.mapstruct.factory.Mappers;

import com.tutorialspoint.entity.CarEntity;
import com.tutorialspoint.mapper.CarMapper;
import com.tutorialspoint.model.Car;

public class CarMapperTest {
   private CarMapper carMapper
      = Mappers.getMapper(CarMapper.class);

   @Test
   public void testEntityToModel() {
      CarEntity entity = new CarEntity();
      entity.setPrice(345000);
      entity.setId(1);
      entity.setManufacturingDate(new GregorianCalendar(2015, 3, 5));
      Car model = carMapper.getModelFromEntity(entity);
      assertEquals(model.getPrice(), "$345000.00");
      assertEquals(entity.getId(), model.getId());
      assertEquals("05.04.2015", model.getManufacturingDate());
   }
}

執行以下命令測試對映。

mvn clean test

命令成功後。驗證輸出。

mvn clean test
[INFO] Scanning for projects...
...
[INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ mapping ---
[INFO] Surefire report directory: \mvn\mapping\target\surefire-reports

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running com.tutorialspoint.mapping.CarMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.035 sec
Running com.tutorialspoint.mapping.DeliveryAddressMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0 sec
Running com.tutorialspoint.mapping.StudentMapperTest
Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.001 sec

Results :

Tests run: 4, Failures: 0, Errors: 0, Skipped: 0
...

MapStruct - 使用常量

MapStruct 允許將常量值對映到屬性。

語法

@Mapping(target = "target-property", const = "const-value")

這裡

• 目標屬性 - 我們正在進行對映的屬性。

• 常量值 - 對映器將常量值對映到目標屬性。

以下示例演示了相同的功能。

示例

在 Eclipse 中開啟專案對映，該對映在使用 dateFormat 對映章節中進行了更新。

使用以下程式碼更新 CarEntity.java −

CarEntity.java

package com.tutorialspoint.entity;
import java.util.GregorianCalendar;

public class CarEntity {
   private int id;
   private double price;
   private GregorianCalendar manufacturingDate;
   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
   public double getPrice() {
      return price;
   }
   public void setPrice(double price) {
      this.price = price;
   }
   public GregorianCalendar getManufacturingDate() {
      return manufacturingDate;
   }
   public void setManufacturingDate(GregorianCalendar manufacturingDate) {
      this.manufacturingDate = manufacturingDate;
   }
}

使用以下程式碼更新 Car.java −

Car.java

package com.tutorialspoint.model;

public class Car {
   private int id;
   private String price;
   private String manufacturingDate;
   private String brand;
   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
   public String getPrice() {
      return price;
   }
   public void setPrice(String price) {
      this.price = price;
   }
   public String getManufacturingDate() {
      return manufacturingDate;
   }
   public void setManufacturingDate(String manufacturingDate) {
      this.manufacturingDate = manufacturingDate;
   }
   public String getBrand() {
      return brand;
   }
   public void setBrand(String brand) {
      this.brand = brand;
   }
}

使用以下程式碼更新 CarMapper.java −

CarMapper.java

package com.tutorialspoint.mapper;

import org.mapstruct.Mapper;
import org.mapstruct.Mapping;

import com.tutorialspoint.entity.CarEntity;
import com.tutorialspoint.model.Car;

@Mapper
public interface CarMapper {
   @Mapping(target = "brand", constant = "BMW")
   @Mapping(source = "price", target = "price", numberFormat = "$#.00")
   @Mapping(source = "manufacturingDate", target = "manufacturingDate", dateFormat = "dd.MM.yyyy")
   Car getModelFromEntity(CarEntity carEntity);
}

使用以下程式碼更新 CarMapperTest.java −

CarMapperTest.java

package com.tutorialspoint.mapping;

import static org.junit.jupiter.api.Assertions.assertEquals;
import java.util.GregorianCalendar;
import org.junit.jupiter.api.Test;
import org.mapstruct.factory.Mappers;

import com.tutorialspoint.entity.CarEntity;
import com.tutorialspoint.mapper.CarMapper;
import com.tutorialspoint.model.Car;

public class CarMapperTest {
   private CarMapper carMapper
      = Mappers.getMapper(CarMapper.class);

   @Test
   public void testEntityToModel() {
      CarEntity entity = new CarEntity();
      entity.setPrice(345000);
      entity.setId(1);
      entity.setManufacturingDate(new GregorianCalendar(2015, 3, 5));
      Car model = carMapper.getModelFromEntity(entity);
      assertEquals(model.getPrice(), "$345000.00");
      assertEquals(entity.getId(), model.getId());
      assertEquals("05.04.2015", model.getManufacturingDate());
      assertEquals("BMW", model.getBrand());
   }
}

執行以下命令測試對映。

mvn clean test

命令成功後。驗證輸出。

mvn clean test
[INFO] Scanning for projects...
...
[INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ mapping ---
[INFO] Surefire report directory: \mvn\mapping\target\surefire-reports

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running com.tutorialspoint.mapping.CarMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.035 sec
Running com.tutorialspoint.mapping.DeliveryAddressMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0 sec
Running com.tutorialspoint.mapping.StudentMapperTest
Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.001 sec

Results :

Tests run: 4, Failures: 0, Errors: 0, Skipped: 0
...

MapStruct - 使用 defaultValue

使用 Mapstruct，如果源屬性為 null，我們可以使用 @Mapping 註解的 defaultValue 屬性傳遞預設值。

語法

@Mapping(target = "target-property", source="source-property" 
defaultValue = "default-value")

這裡

• 預設值 - 如果源屬性為 null，則目標屬性將設定為預設值。

以下示例演示了相同的功能。

示例

在 Eclipse 中開啟專案對映，該對映在使用 Constant 對映章節中進行了更新。

使用以下程式碼更新 CarEntity.java −

CarEntity.java

package com.tutorialspoint.entity;
import java.util.GregorianCalendar;

public class CarEntity {
   private int id;
   private double price;
   private GregorianCalendar manufacturingDate;
   private String name;
   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
   public double getPrice() {
      return price;
   }
   public void setPrice(double price) {
      this.price = price;
   }
   public GregorianCalendar getManufacturingDate() {
      return manufacturingDate;
   }
   public void setManufacturingDate(GregorianCalendar manufacturingDate) {
      this.manufacturingDate = manufacturingDate;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
}

使用以下程式碼更新 Car.java −

Car.java

package com.tutorialspoint.model;

public class Car {
   private int id;
   private String price;
   private String manufacturingDate;
   private String brand;
   private String name;
   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
   public String getPrice() {
      return price;
   }
   public void setPrice(String price) {
      this.price = price;
   }
   public String getManufacturingDate() {
      return manufacturingDate;
   }
   public void setManufacturingDate(String manufacturingDate) {
      this.manufacturingDate = manufacturingDate;
   }
   public String getBrand() {
      return brand;
   }
   public void setBrand(String brand) {
      this.brand = brand;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
}

使用以下程式碼更新 CarMapper.java −

CarMapper.java

package com.tutorialspoint.mapper;

import org.mapstruct.Mapper;
import org.mapstruct.Mapping;

import com.tutorialspoint.entity.CarEntity;
import com.tutorialspoint.model.Car;

@Mapper
public interface CarMapper {
   @Mapping(source = "name", target = "name", defaultValue = "Sample")
   @Mapping(target = "brand", constant = "BMW")
   @Mapping(source = "price", target = "price", numberFormat = "$#.00")
   @Mapping(source = "manufacturingDate", target = "manufacturingDate", dateFormat = "dd.MM.yyyy")
   Car getModelFromEntity(CarEntity carEntity);
}

使用以下程式碼更新 CarMapperTest.java −

CarMapperTest.java

package com.tutorialspoint.mapping;

import static org.junit.jupiter.api.Assertions.assertEquals;
import java.util.GregorianCalendar;
import org.junit.jupiter.api.Test;
import org.mapstruct.factory.Mappers;

import com.tutorialspoint.entity.CarEntity;
import com.tutorialspoint.mapper.CarMapper;
import com.tutorialspoint.model.Car;

public class CarMapperTest {
   private CarMapper carMapper
      = Mappers.getMapper(CarMapper.class);

   @Test
   public void testEntityToModel() {
      CarEntity entity = new CarEntity();
      entity.setPrice(345000);
      entity.setId(1);
      entity.setManufacturingDate(new GregorianCalendar(2015, 3, 5));
      Car model = carMapper.getModelFromEntity(entity);
      assertEquals(model.getPrice(), "$345000.00");
      assertEquals(entity.getId(), model.getId());
      assertEquals("05.04.2015", model.getManufacturingDate());
      assertEquals("Sample", model.getName());
      assertEquals("BMW", model.getBrand());
   }
}

執行以下命令測試對映。

mvn clean test

命令成功後。驗證輸出。

mvn clean test
[INFO] Scanning for projects...
...
[INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ mapping ---
[INFO] Surefire report directory: \mvn\mapping\target\surefire-reports

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running com.tutorialspoint.mapping.CarMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.035 sec
Running com.tutorialspoint.mapping.DeliveryAddressMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0 sec
Running com.tutorialspoint.mapping.StudentMapperTest
Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.001 sec

Results :

Tests run: 4, Failures: 0, Errors: 0, Skipped: 0
...

MapStruct - 使用 defaultExpression

使用 Mapstruct，如果源屬性為 null，我們可以使用 @Mapping 註解的 defaultExpression 屬性傳遞計算值。

語法

@Mapping(target = "target-property", source="source-property" defaultExpression = "default-value-method")

這裡

• 預設值方法 - 如果源屬性為 null，則目標屬性將設定為預設值方法的結果。

以下示例演示了相同的功能。

示例

在 Eclipse 中開啟專案對映，該對映在使用 defaultValue 對映章節中進行了更新。

使用以下程式碼更新 CarEntity.java −

CarEntity.java

package com.tutorialspoint.entity;
import java.util.GregorianCalendar;

public class CarEntity {
   private int id;
   private double price;
   private GregorianCalendar manufacturingDate;
   private String name;
   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
   public double getPrice() {
      return price;
   }
   public void setPrice(double price) {
      this.price = price;
   }
   public GregorianCalendar getManufacturingDate() {
      return manufacturingDate;
   }
   public void setManufacturingDate(GregorianCalendar manufacturingDate) {
      this.manufacturingDate = manufacturingDate;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
}

使用以下程式碼更新 Car.java −

Car.java

package com.tutorialspoint.model;
public class Car {
   private int id;
   private String price;
   private String manufacturingDate;
   private String brand;
   private String name;
   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
   public String getPrice() {
      return price;
   }
   public void setPrice(String price) {
      this.price = price;
   }
   public String getManufacturingDate() {
      return manufacturingDate;
   }
   public void setManufacturingDate(String manufacturingDate) {
      this.manufacturingDate = manufacturingDate;
   }
   public String getBrand() {
      return brand;
   }
   public void setBrand(String brand) {
      this.brand = brand;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
}

使用以下程式碼更新 CarMapper.java −

CarMapper.java

package com.tutorialspoint.mapper;

import org.mapstruct.Mapper;
import org.mapstruct.Mapping;
import com.tutorialspoint.entity.CarEntity;
import com.tutorialspoint.model.Car;
import java.util.UUID;

@Mapper( imports = UUID.class )
public interface CarMapper {
   @Mapping(source = "name", target = "name", defaultExpression = "java(UUID.randomUUID().toString())")
   @Mapping(target = "brand", constant = "BMW")
   @Mapping(source = "price", target = "price", numberFormat = "$#.00")
   @Mapping(source = "manufacturingDate", target = "manufacturingDate", dateFormat = "dd.MM.yyyy")
   Car getModelFromEntity(CarEntity carEntity);
}

使用以下程式碼更新 CarMapperTest.java −

CarMapperTest.java

package com.tutorialspoint.mapping;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import java.util.GregorianCalendar;
import org.junit.jupiter.api.Test;
import org.mapstruct.factory.Mappers;
import com.tutorialspoint.entity.CarEntity;
import com.tutorialspoint.mapper.CarMapper;
import com.tutorialspoint.model.Car;

public class CarMapperTest {
   private CarMapper carMapper=Mappers.getMapper(CarMapper.class);

   @Test
   public void testEntityToModel() {
      CarEntity entity = new CarEntity();
      entity.setPrice(345000);
      entity.setId(1);
      entity.setManufacturingDate(new GregorianCalendar(2015, 3, 5));
      Car model = carMapper.getModelFromEntity(entity);
      assertEquals(model.getPrice(), "$345000.00");
      assertEquals(entity.getId(), model.getId());
      assertEquals("05.04.2015", model.getManufacturingDate());
      assertNotNull(model.getName());
      assertEquals("BMW", model.getBrand());
   }
}

執行以下命令測試對映。

mvn clean test

輸出

命令成功後。驗證輸出。

mvn clean test
[INFO] Scanning for projects...
...
[INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ mapping ---
[INFO] Surefire report directory: \mvn\mapping\target\surefire-reports

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running com.tutorialspoint.mapping.CarMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.035 sec
Running com.tutorialspoint.mapping.DeliveryAddressMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0 sec
Running com.tutorialspoint.mapping.StudentMapperTest
Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.001 sec

Results :

Tests run: 4, Failures: 0, Errors: 0, Skipped: 0
...

MapStruct - 列表對映

使用 Mapstruct，我們可以像對映基本型別一樣對映列表。要獲取物件列表，我們應該提供一個可以對映物件的對映器方法。

語法

@Mapper
public interface CarMapper {
   List<String> getListOfStrings(List<Integer> listOfIntegers);
   List<Car> getCars(List<CarEntity> carEntities);
   Car getModelFromEntity(CarEntity carEntity);
}

以下示例演示了相同的功能。

示例

在 Eclipse 中開啟專案對映，該對映在使用 defaultExpression 對映章節中進行了更新。

使用以下程式碼更新 CarEntity.java −

CarEntity.java

package com.tutorialspoint.entity;
import java.util.GregorianCalendar;

public class CarEntity {
   private int id;
   private double price;
   private GregorianCalendar manufacturingDate;
   private String name;
   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
   public double getPrice() {
      return price;
   }
   public void setPrice(double price) {
      this.price = price;
   }
   public GregorianCalendar getManufacturingDate() {
      return manufacturingDate;
   }
   public void setManufacturingDate(GregorianCalendar manufacturingDate) {
      this.manufacturingDate = manufacturingDate;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
}

使用以下程式碼更新 Car.java −

Car.java

package com.tutorialspoint.model;

public class Car {
   private int id;
   private String price;
   private String manufacturingDate;
   private String brand;
   private String name;
   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
   public String getPrice() {
      return price;
   }
   public void setPrice(String price) {
      this.price = price;
   }
   public String getManufacturingDate() {
      return manufacturingDate;
   }
   public void setManufacturingDate(String manufacturingDate) {
      this.manufacturingDate = manufacturingDate;
   }
   public String getBrand() {
      return brand;
   }
   public void setBrand(String brand) {
      this.brand = brand;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
}

使用以下程式碼更新 CarMapper.java −

CarMapper.java

package com.tutorialspoint.mapper;

import org.mapstruct.Mapper;
import org.mapstruct.Mapping;

import com.tutorialspoint.entity.CarEntity;
import com.tutorialspoint.model.Car;

import java.util.List;
import java.util.UUID;

@Mapper( imports = UUID.class )
public interface CarMapper {
   @Mapping(source = "name", target = "name", defaultExpression = "java(UUID.randomUUID().toString())")
   @Mapping(target = "brand", constant = "BMW")
   @Mapping(source = "price", target = "price", numberFormat = "$#.00")
   @Mapping(source = "manufacturingDate", target = "manufacturingDate", dateFormat = "dd.MM.yyyy")
   Car getModelFromEntity(CarEntity carEntity);

   List<String> getListOfStrings(List<Integer> listOfIntegers);
   List<Car> getCars(List<CarEntity> carEntities);
}

使用以下程式碼更新 CarMapperTest.java −

CarMapperTest.java

package com.tutorialspoint.mapping;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNotNull;

import java.util.Arrays;
import java.util.GregorianCalendar;
import java.util.List;

import org.junit.jupiter.api.Test;
import org.mapstruct.factory.Mappers;

import com.tutorialspoint.entity.CarEntity;
import com.tutorialspoint.mapper.CarMapper;
import com.tutorialspoint.model.Car;

public class CarMapperTest {
   private CarMapper carMapper
      = Mappers.getMapper(CarMapper.class);

   @Test
   public void testEntityToModel() {
      CarEntity entity = new CarEntity();
      entity.setPrice(345000);
      entity.setId(1);
      entity.setManufacturingDate(new GregorianCalendar(2015, 3, 5));

      CarEntity entity1 = new CarEntity();
      entity1.setPrice(445000);
      entity1.setId(2);
      entity1.setManufacturingDate(new GregorianCalendar(2015, 3, 5));

      List<CarEntity> carEntities = Arrays.asList(entity, entity1);

      Car model = carMapper.getModelFromEntity(entity);
      assertEquals("$345000.00",model.getPrice());
      assertEquals(entity.getId(), model.getId());

      assertEquals("BMW", model.getBrand());
      assertEquals("05.04.2015", model.getManufacturingDate());

      List<Integer> list = Arrays.asList(1,2,3);
      List<String> listOfStrings = carMapper.getListOfStrings(list);
      List<Car> listOfCars = carMapper.getCars(carEntities);

      assertEquals(3, listOfStrings.size());
      assertEquals(2, listOfCars.size());
   }
}

執行以下命令測試對映。

mvn clean test

命令成功後。驗證輸出。

mvn clean test
[INFO] Scanning for projects...
...
[INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ mapping ---
[INFO] Surefire report directory: \mvn\mapping\target\surefire-reports

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running com.tutorialspoint.mapping.CarMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.035 sec
Running com.tutorialspoint.mapping.DeliveryAddressMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0 sec
Running com.tutorialspoint.mapping.StudentMapperTest
Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.001 sec

Results :

Tests run: 4, Failures: 0, Errors: 0, Skipped: 0
...

MapStruct - Map 對映

使用 Mapstruct，我們可以使用 @MapMapping 註解建立對映物件。其他對映規則與我們之前看到的相同。

語法

@Mapper
public interface UtilityMapper {
   @MapMapping(valueDateFormat = "dd.MM.yyyy")
   Map<String, String> getMap(Map<Long, GregorianCalendar> source);
}

以下示例演示了相同的功能。

示例

在 Eclipse 中開啟專案對映，該對映在對映列表章節中進行了更新。

使用以下程式碼建立 UtilityMapper.java −

UtilityMapper.java

package com.tutorialspoint.mapper;

import java.util.GregorianCalendar;
import java.util.Map;

import org.mapstruct.MapMapping;
import org.mapstruct.Mapper;

@Mapper
public interface UtilityMapper {
   @MapMapping(valueDateFormat = "dd.MM.yyyy")
   Map<String, String> getMap(Map<Long, GregorianCalendar> source);
}

使用以下程式碼建立 UtilityMapperTest.java −

UtilityMapperTest.java

package com.tutorialspoint.mapping;

import static org.junit.jupiter.api.Assertions.assertEquals;

import java.util.GregorianCalendar;
import java.util.HashMap;
import java.util.Map;

import org.junit.jupiter.api.Test;
import org.mapstruct.factory.Mappers;

import com.tutorialspoint.mapper.UtilityMapper;

public class UtilityMapperTest {
   private UtilityMapper utilityMapper
      = Mappers.getMapper(UtilityMapper.class);

   @Test
   public void testMapMapping() {
      Map<Long, GregorianCalendar> source = new HashMap<>();
      source.put(1L, new GregorianCalendar(2015, 3, 5));

      Map<String, String> target = utilityMapper.getMap(source);
      assertEquals("05.04.2015", target.get("1"));		
   }
}

執行以下命令測試對映。

mvn clean test

命令成功後。驗證輸出。

mvn clean test
[INFO] Scanning for projects...
...
[INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ mapping ---
[INFO] Surefire report directory: \mvn\mapping\target\surefire-reports

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running com.tutorialspoint.mapping.CarMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.327 sec
Running com.tutorialspoint.mapping.DeliveryAddressMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.001 sec
Running com.tutorialspoint.mapping.StudentMapperTest
Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.001 sec
Running com.tutorialspoint.mapping.UtilityMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.001 sec

Results :

Tests run: 5, Failures: 0, Errors: 0, Skipped: 0
...

MapStruct - 對映流

使用 Mapstruct，我們可以像處理集合一樣建立流的對映。

語法

@Mapper
public interface UtilityMapper {
   Stream<String> getStream(Stream<Integer> source);
}

以下示例演示了相同的功能。

示例

在 Eclipse 中開啟專案對映，該對映在對映對映章節中進行了更新。

使用以下程式碼更新 UtilityMapper.java −

UtilityMapper.java

package com.tutorialspoint.mapper;

import java.util.GregorianCalendar;
import java.util.Map;
import java.util.stream.Stream;
import org.mapstruct.MapMapping;
import org.mapstruct.Mapper;

@Mapper
public interface UtilityMapper {
   @MapMapping(valueDateFormat = "dd.MM.yyyy")
   Map<String, String> getMap(Map<Long, GregorianCalendar> source);
   Stream<String> getStream(Stream<Integer> source);
}

使用以下程式碼更新 UtilityMapperTest.java −

UtilityMapperTest.java

package com.tutorialspoint.mapping;

import static org.junit.jupiter.api.Assertions.assertEquals;
import java.util.Arrays;
import java.util.GregorianCalendar;
import java.util.HashMap;
import java.util.Map;
import java.util.stream.Stream;
import org.junit.jupiter.api.Test;
import org.mapstruct.factory.Mappers;
import com.tutorialspoint.mapper.UtilityMapper;

public class UtilityMapperTest {
   private UtilityMapper utilityMapper=Mappers.getMapper(UtilityMapper.class);
   
   @Test
   public void testMapMapping() {
      Map<Long, GregorianCalendar> source = new HashMap<>();
      source.put(1L, new GregorianCalendar(2015, 3, 5));

      Map<String, String> target = utilityMapper.getMap(source);
      assertEquals("05.04.2015", target.get("1"));		
   }
   @Test
   public void testGetStream() {
      Stream<Integer> numbers = Arrays.asList(1, 2, 3, 4).stream();

      Stream<String> strings = utilityMapper.getStream(numbers);
      assertEquals(4, strings.count());			
   }
}

執行以下命令測試對映。

mvn clean test

輸出

命令成功後。驗證輸出。

mvn clean test
[INFO] Scanning for projects...
...
[INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ mapping ---
[INFO] Surefire report directory: \mvn\mapping\target\surefire-reports

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running com.tutorialspoint.mapping.CarMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.327 sec
Running com.tutorialspoint.mapping.DeliveryAddressMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.001 sec
Running com.tutorialspoint.mapping.StudentMapperTest
Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.001 sec
Running com.tutorialspoint.mapping.UtilityMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.001 sec

Results :

Tests run: 5, Failures: 0, Errors: 0, Skipped: 0
...

MapStruct - 列舉對映

Mapstruct 自動對映列舉。名稱相同的列舉會自動對映。如果名稱不同，我們可以使用 @ValueMapping 註解進行對映。

語法

@Mapper
public interface UtilityMapper {
   @ValueMapping(source = "EXTRA", target = "SPECIAL")
   PlacedOrderType getEnum(OrderType order);
}

以下示例演示了相同的功能。

示例

在 Eclipse 中開啟專案對映，該對映在對映流章節中進行了更新。

使用以下程式碼建立 OrderType.java −

OrderType.java

package com.tutorialspoint.enums;
public enum OrderType {
   EXTRA, NORMAL, STANDARD
}

使用以下程式碼建立 PlacedOrderType.java −

PlacedOrderType.java

package com.tutorialspoint.enums;
public enum PlacedOrderType {
   SPECIAL, NORMAL, STANDARD
}

使用以下程式碼更新 UtilityMapper.java −

UtilityMapper.java

package com.tutorialspoint.mapper;

import java.util.GregorianCalendar;
import java.util.Map;
import java.util.stream.Stream;
import org.mapstruct.MapMapping;
import org.mapstruct.Mapper;
import org.mapstruct.ValueMapping;
import com.tutorialspoint.enums.OrderType;
import com.tutorialspoint.enums.PlacedOrderType;

@Mapper
public interface UtilityMapper {
   @MapMapping(valueDateFormat = "dd.MM.yyyy")
   Map<String, String> getMap(Map<Long, GregorianCalendar> source);
   Stream<String> getStream(Stream<Integer> source);
   
   @ValueMapping(source = "EXTRA", target = "SPECIAL")
   PlacedOrderType getEnum(OrderType order);
}

使用以下程式碼更新 UtilityMapperTest.java −

UtilityMapperTest.java

package com.tutorialspoint.mapping;

import static org.junit.jupiter.api.Assertions.assertEquals;
import java.util.Arrays;
import java.util.GregorianCalendar;
import java.util.HashMap;
import java.util.Map;
import java.util.stream.Stream;
import org.junit.jupiter.api.Test;
import org.mapstruct.factory.Mappers;
import com.tutorialspoint.enums.OrderType;
import com.tutorialspoint.enums.PlacedOrderType;
import com.tutorialspoint.mapper.UtilityMapper;

public class UtilityMapperTest {
   private UtilityMapper utilityMapper=Mappers.getMapper(UtilityMapper.class);

   @Test
   public void testMapMapping() {
      Map<Long, GregorianCalendar> source = new HashMap<>();
      source.put(1L, new GregorianCalendar(2015, 3, 5));

      Map<String, String> target = utilityMapper.getMap(source);
      assertEquals("05.04.2015", target.get("1"));		
   }
   @Test
   public void testGetStream() {
      Stream<Integer> numbers = Arrays.asList(1, 2, 3, 4).stream();
      Stream<String> strings = utilityMapper.getStream(numbers);
      assertEquals(4, strings.count());			
   }   
   @Test
   public void testGetEnum() {
      PlacedOrderType placedOrderType = utilityMapper.getEnum(OrderType.EXTRA);
      PlacedOrderType placedOrderType1 = utilityMapper.getEnum(OrderType.NORMAL);
      PlacedOrderType placedOrderType2 = utilityMapper.getEnum(OrderType.STANDARD);
      assertEquals(PlacedOrderType.SPECIAL.name(), placedOrderType.name());
      assertEquals(PlacedOrderType.NORMAL.name(), placedOrderType1.name());
      assertEquals(PlacedOrderType.STANDARD.name(), placedOrderType2.name());
   }
}

執行以下命令測試對映。

mvn clean test

輸出

命令成功後。驗證輸出。

mvn clean test
[INFO] Scanning for projects...
...
[INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ mapping ---
[INFO] Surefire report directory: \mvn\mapping\target\surefire-reports

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running com.tutorialspoint.mapping.CarMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.256 sec
Running com.tutorialspoint.mapping.DeliveryAddressMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.001 sec
Running com.tutorialspoint.mapping.StudentMapperTest
Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0 sec
Running com.tutorialspoint.mapping.UtilityMapperTest
Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0 sec

Results :

Tests run: 7, Failures: 0, Errors: 0, Skipped: 0
...

MapStruct - 丟擲異常

Mapstruct 對映器允許丟擲特定異常。考慮自定義對映方法的情況，如果資料無效，我們希望丟擲自定義異常。

語法

@Mapper(uses=DateMapper.class)
public interface UtilityMapper {
    CarEntity getCarEntity(Car car) throws ParseException;
}

以下示例演示了相同的功能。

示例

在 Eclipse 中開啟專案對映，該對映在對映列舉章節中進行了更新。

使用以下程式碼更新 UtilityMapper.java −

UtilityMapper.java

package com.tutorialspoint.mapper;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Map;
import java.util.stream.Stream;

import org.mapstruct.MapMapping;
import org.mapstruct.Mapper;
import org.mapstruct.ValueMapping;

import com.tutorialspoint.entity.CarEntity;
import com.tutorialspoint.enums.OrderType;
import com.tutorialspoint.enums.PlacedOrderType;
import com.tutorialspoint.model.Car;

@Mapper(uses=DateMapper.class)
public interface UtilityMapper {
   @MapMapping(valueDateFormat = "dd.MM.yyyy")
   Map<String, String> getMap(Map<Long, GregorianCalendar> source);

   Stream<String> getStream(Stream<Integer> source);

   @ValueMapping(source = "EXTRA", target = "SPECIAL")
   PlacedOrderType getEnum(OrderType order);

   CarEntity getCarEntity(Car car) throws ParseException;
}

class DateMapper {
   public String asString(GregorianCalendar date) {
      return date != null ? new SimpleDateFormat( "yyyy-MM-dd" )
         .format( date.getTime() ) : null;
   }

   public GregorianCalendar asDate(String date) throws ParseException {
      Date date1 = date != null ? new SimpleDateFormat( "yyyy-MM-dd" )
         .parse( date ) : null;
      if(date1 != null) {
         return new GregorianCalendar(date1.getYear(), date1.getMonth(),date1.getDay());
      }
      return null;        
   }
}

使用以下程式碼更新 UtilityMapperTest.java −

UtilityMapperTest.java

package com.tutorialspoint.mapping;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertTrue;

import java.text.ParseException;
import java.util.Arrays;
import java.util.GregorianCalendar;
import java.util.HashMap;
import java.util.Map;
import java.util.stream.Stream;

import org.junit.jupiter.api.Test;
import org.mapstruct.factory.Mappers;

import com.tutorialspoint.entity.CarEntity;
import com.tutorialspoint.enums.OrderType;
import com.tutorialspoint.enums.PlacedOrderType;
import com.tutorialspoint.mapper.UtilityMapper;
import com.tutorialspoint.model.Car;

public class UtilityMapperTest {
   private UtilityMapper utilityMapper
      = Mappers.getMapper(UtilityMapper.class);

   @Test
   public void testMapMapping() {
      Map<Long, GregorianCalendar> source = new HashMap<>();
      source.put(1L, new GregorianCalendar(2015, 3, 5));

      Map<String, String> target = utilityMapper.getMap(source);
      assertEquals("2015-04-05", target.get("1"));		
   }

   @Test
   public void testGetStream() {
      Stream<Integer> numbers = Arrays.asList(1, 2, 3, 4).stream();

      Stream<String> strings = utilityMapper.getStream(numbers);
      assertEquals(4, strings.count());			
   }

   @Test
   public void testGetEnum() {
      PlacedOrderType placedOrderType = utilityMapper.getEnum(OrderType.EXTRA);
      PlacedOrderType placedOrderType1 = utilityMapper.getEnum(OrderType.NORMAL);
      PlacedOrderType placedOrderType2 = utilityMapper.getEnum(OrderType.STANDARD);
      assertEquals(PlacedOrderType.SPECIAL.name(), placedOrderType.name());
      assertEquals(PlacedOrderType.NORMAL.name(), placedOrderType1.name());
      assertEquals(PlacedOrderType.STANDARD.name(), placedOrderType2.name());
   }

   @Test
   public void testGetCar() {
      Car car = new Car();
      car.setId(1);
      car.setManufacturingDate("11/10/2020");
      boolean exceptionOccured = false;
      try {
         CarEntity carEntity = utilityMapper.getCarEntity(car);
      } catch (ParseException e) {
         exceptionOccured = true;
      }
      assertTrue(exceptionOccured);
   }
}

執行以下命令測試對映。

mvn clean test

命令成功後。驗證輸出。

mvn clean test
[INFO] Scanning for projects...
...
[INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ mapping ---
[INFO] Surefire report directory: \mvn\mapping\target\surefire-reports

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running com.tutorialspoint.mapping.CarMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.256 sec
Running com.tutorialspoint.mapping.DeliveryAddressMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.001 sec
Running com.tutorialspoint.mapping.StudentMapperTest
Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0 sec
Running com.tutorialspoint.mapping.UtilityMapperTest
Tests run: 4, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0 sec

Results :

Tests run: 8, Failures: 0, Errors: 0, Skipped: 0
...

MapStruct - 使用自定義對映器

Mapstruct 對映器允許建立自定義對映器方法來對映物件。對於對映器介面，我們可以新增預設方法。

語法

@Mapper(uses=DateMapper.class)
public interface UtilityMapper {
   default Car getCar(CarEntity entity) {
      Car car = new Car();
      car.setId(entity.getId());
      car.setName(entity.getName());
      return car;
   }
}

以下示例演示了相同的功能。

示例

在 Eclipse 中開啟專案對映，該對映在對映列舉章節中進行了更新。

使用以下程式碼更新 UtilityMapper.java −

UtilityMapper.java

package com.tutorialspoint.mapper;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Map;
import java.util.stream.Stream;

import org.mapstruct.MapMapping;
import org.mapstruct.Mapper;
import org.mapstruct.ValueMapping;

import com.tutorialspoint.entity.CarEntity;
import com.tutorialspoint.enums.OrderType;
import com.tutorialspoint.enums.PlacedOrderType;
import com.tutorialspoint.model.Car;

@Mapper(uses=DateMapper.class)
public interface UtilityMapper {
   @MapMapping(valueDateFormat = "dd.MM.yyyy")
   Map<String, String> getMap(Map<Long, GregorianCalendar> source);

   Stream<String> getStream(Stream<Integer> source);

   @ValueMapping(source = "EXTRA", target = "SPECIAL")
   PlacedOrderType getEnum(OrderType order);

   CarEntity getCarEntity(Car car) throws ParseException;
   
   default Car getCar(CarEntity entity) {
      Car car = new Car();
      car.setId(entity.getId());
      car.setName(entity.getName());
      return car;
   }
}

class DateMapper {
   public String asString(GregorianCalendar date) {
      return date != null ? new SimpleDateFormat( "yyyy-MM-dd" )
         .format( date.getTime() ) : null;
   }

   public GregorianCalendar asDate(String date) throws ParseException {
      Date date1 = date != null ? new SimpleDateFormat( "yyyy-MM-dd" )
         .parse( date ) : null;
      if(date1 != null) {
         return new GregorianCalendar(date1.getYear(), date1.getMonth(),date1.getDay());
      }
      return null;        
   }
}

使用以下程式碼更新 UtilityMapperTest.java −

UtilityMapperTest.java

package com.tutorialspoint.mapping;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertTrue;

import java.text.ParseException;
import java.util.Arrays;
import java.util.GregorianCalendar;
import java.util.HashMap;
import java.util.Map;
import java.util.stream.Stream;

import org.junit.jupiter.api.Test;
import org.mapstruct.factory.Mappers;

import com.tutorialspoint.entity.CarEntity;
import com.tutorialspoint.enums.OrderType;
import com.tutorialspoint.enums.PlacedOrderType;
import com.tutorialspoint.mapper.UtilityMapper;
import com.tutorialspoint.model.Car;

public class UtilityMapperTest {
   private UtilityMapper utilityMapper
      = Mappers.getMapper(UtilityMapper.class);

   @Test
   public void testMapMapping() {
      Map<Long, GregorianCalendar> source = new HashMap<>();
      source.put(1L, new GregorianCalendar(2015, 3, 5));

      Map<String, String> target = utilityMapper.getMap(source);
      assertEquals("2015-04-05", target.get("1"));		
   }

   @Test
   public void testGetStream() {
      Stream<Integer> numbers = Arrays.asList(1, 2, 3, 4).stream();
      Stream<String> strings = utilityMapper.getStream(numbers);
      assertEquals(4, strings.count());			
   }

   @Test
   public void testGetEnum() {
      PlacedOrderType placedOrderType = utilityMapper.getEnum(OrderType.EXTRA);
      PlacedOrderType placedOrderType1 = utilityMapper.getEnum(OrderType.NORMAL);
      PlacedOrderType placedOrderType2 = utilityMapper.getEnum(OrderType.STANDARD);
      assertEquals(PlacedOrderType.SPECIAL.name(), placedOrderType.name());
      assertEquals(PlacedOrderType.NORMAL.name(), placedOrderType1.name());
      assertEquals(PlacedOrderType.STANDARD.name(), placedOrderType2.name());
   }

   @Test
   public void testGetCarEntity() {
      Car car = new Car();
      car.setId(1);
      car.setManufacturingDate("11/10/2020");
      boolean exceptionOccured = false;
      try {
         CarEntity carEntity = utilityMapper.getCarEntity(car);
      } catch (ParseException e) {
         exceptionOccured = true;
      }
      assertTrue(exceptionOccured);
   }

   @Test
   public void testGetCar() {
      CarEntity entity = new CarEntity();
      entity.setId(1);
      entity.setName("ZEN");

      Car car = utilityMapper.getCar(entity);

      assertEquals(entity.getId(), car.getId());
      assertEquals(entity.getName(), car.getName());		
   }
}

執行以下命令測試對映。

mvn clean test

命令成功後。驗證輸出。

mvn clean test
[INFO] Scanning for projects...
...
[INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ mapping ---
[INFO] Surefire report directory: \mvn\mapping\target\surefire-reports

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running com.tutorialspoint.mapping.CarMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.256 sec
Running com.tutorialspoint.mapping.DeliveryAddressMapperTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.001 sec
Running com.tutorialspoint.mapping.StudentMapperTest
Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0 sec
Running com.tutorialspoint.mapping.UtilityMapperTest
Tests run: 5, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0 sec

Results :

Tests run: 9, Failures: 0, Errors: 0, Skipped: 0
...