Spring Boot - 傳送電子郵件

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使用 Spring Boot RESTful web 服務，您可以使用 Gmail 傳輸層安全協議傳送電子郵件。本章，我們將詳細瞭解如何使用此功能。

首先，我們需要在您的構建配置檔案中新增 Spring Boot Starter Mail 依賴項。

Maven 使用者可以將以下依賴項新增到 pom.xml 檔案中。

<dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-mail</artifactId>
</dependency>

Gradle 使用者可以在您的 build.gradle 檔案中新增以下依賴項。

compile('org.springframework.boot:spring-boot-starter-mail')

以下是主 Spring Boot 應用類檔案的程式碼：

package com.tutorialspoint.emailapp;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class EmailappApplication {
   public static void main(String[] args) {
      SpringApplication.run(EmailappApplication.class, args);
   }
}

您可以在 Rest Controller 類檔案中編寫一個簡單的 Rest API 來發送電子郵件，如下所示。

package com.tutorialspoint.emailapp;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class EmailController {
   @GetMapping(value = "/sendemail")
   public String sendEmail() {
      return "Email sent successfully";
   }   
}

您可以編寫一個方法來發送帶有附件的電子郵件。定義 mail.smtp 屬性並使用 PasswordAuthentication。

private void sendmail() throws AddressException, MessagingException, IOException {
   Properties props = new Properties();
   props.put("mail.smtp.auth", "true");
   props.put("mail.smtp.starttls.enable", "true");
   props.put("mail.smtp.host", "smtp.gmail.com");
   props.put("mail.smtp.port", "587");
   
   Session session = Session.getInstance(props, new javax.mail.Authenticator() {
      protected PasswordAuthentication getPasswordAuthentication() {
         return new PasswordAuthentication("tutorialspoint@gmail.com", "<your password>");
      }
   });
   Message msg = new MimeMessage(session);
   msg.setFrom(new InternetAddress("tutorialspoint@gmail.com", false));

   msg.setRecipients(Message.RecipientType.TO, InternetAddress.parse("tutorialspoint@gmail.com"));
   msg.setSubject("Tutorials point email");
   msg.setContent("Tutorials point email", "text/html");
   msg.setSentDate(new Date());

   MimeBodyPart messageBodyPart = new MimeBodyPart();
   messageBodyPart.setContent("Tutorials point email", "text/html");

   Multipart multipart = new MimeMultipart();
   multipart.addBodyPart(messageBodyPart);
   MimeBodyPart attachPart = new MimeBodyPart();

   attachPart.attachFile("/var/tmp/image19.png");
   multipart.addBodyPart(attachPart);
   msg.setContent(multipart);
   Transport.send(msg);   
}

現在，從 Rest API 呼叫上面的 sendmail() 方法，如下所示：

@GetMapping(value = "/sendemail")
public String sendEmail() throws AddressException, MessagingException, IOException {
   sendmail();
   return "Email sent successfully";   
}

注意 - 傳送電子郵件之前，請在您的 Gmail 帳戶設定中啟用“允許安全性較低的應用”。

建立郵件伺服器

首先，從 Spring Initializer 頁面下載 Spring Boot 專案，並選擇 Spring Web 和 Java Mail Sender 作為依賴項。請參考下面的截圖：

Creating Spring Mail Server

完整的構建配置檔案如下所示。

Maven – pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>
   <parent>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-parent</artifactId>
      <version>3.3.4</version>
      <relativePath/> <!-- lookup parent from repository -->
   </parent>
   <groupId>com.tutorialspoint</groupId>
   <artifactId>emailapp</artifactId>
   <version>0.0.1-SNAPSHOT</version>
   <name>emailapp</name>
   <description>Demo project for Spring Boot</description>
   <url/>
   <licenses>
      <license/>
   </licenses>
   <developers>
      <developer/>
   </developers>
   <scm>
      <connection/>
      <developerConnection/>
      <tag/>
      <url/>
   </scm>
   <properties>
      <java.version>21</java.version>
   </properties>
   <dependencies>
      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-mail</artifactId>
      </dependency>
      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-web</artifactId>
      </dependency>
      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-test</artifactId>
         <scope>test</scope>
      </dependency>
   </dependencies>
   <build>
      <plugins>
         <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
         </plugin>
      </plugins>
   </build>
</project>

Gradle – build.gradle

buildscript {
   ext {
      springBootVersion = '3.3.4'
   }
   repositories {
      mavenCentral()
   }
   dependencies {
      classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
   }
}

apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'org.springframework.boot'

group = 'com.tutorialspoint'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = 21

repositories {
   mavenCentral()
}
dependencies {
   compile('org.springframework.boot:spring-boot-starter-web')
   compile('org.springframework.boot:spring-boot-starter-mail')
   testCompile('org.springframework.boot:spring-boot-starter-test')
}

EmailController.java

package com.tutorialspoint.emailapp;

import java.io.IOException;
import java.util.Date;
import java.util.Properties;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import jakarta.mail.Authenticator;
import jakarta.mail.Message;
import jakarta.mail.MessagingException;
import jakarta.mail.Multipart;
import jakarta.mail.PasswordAuthentication;
import jakarta.mail.Session;
import jakarta.mail.Transport;
import jakarta.mail.internet.AddressException;
import jakarta.mail.internet.InternetAddress;
import jakarta.mail.internet.MimeBodyPart;
import jakarta.mail.internet.MimeMessage;
import jakarta.mail.internet.MimeMultipart;

@RestController
public class EmailController {
   @GetMapping(value = "/sendemail")
   public String sendEmail() throws AddressException, MessagingException, IOException {
      sendmail();
      return "Email sent successfully";
   }   

   private void sendmail() throws AddressException, MessagingException, IOException {
      Properties props = new Properties();
      props.put("mail.smtp.auth", "true");
      props.put("mail.smtp.starttls.enable", "true");
      props.put("mail.smtp.host", "smtp.gmail.com");
      props.put("mail.smtp.port", "587");

      Session session = Session.getInstance(props, new Authenticator() {
         protected PasswordAuthentication getPasswordAuthentication() {
            return new PasswordAuthentication("tutorialspoint@gmail.com", "<your password>");
         }
      });
      Message msg = new MimeMessage(session);
      msg.setFrom(new InternetAddress("tutorialspoint@gmail.com", false));

      msg.setRecipients(Message.RecipientType.TO, InternetAddress.parse("tutorialspoint@gmail.com"));
      msg.setSubject("Tutorials point email");
      msg.setContent("Tutorials point email", "text/html");
      msg.setSentDate(new Date());

      MimeBodyPart messageBodyPart = new MimeBodyPart();
      messageBodyPart.setContent("Tutorials point email", "text/html");

      Multipart multipart = new MimeMultipart();
      multipart.addBodyPart(messageBodyPart);
      MimeBodyPart attachPart = new MimeBodyPart();

      attachPart.attachFile("/var/tmp/image19.png");
      multipart.addBodyPart(attachPart);
      msg.setContent(multipart);
      Transport.send(msg);   
   }
}

編譯和執行

現在，您可以建立一個可執行的 JAR 檔案，並使用下面顯示的 Maven 或 Gradle 命令執行 Spring Boot 應用程式：

對於 Maven，您可以使用如下所示的命令：

mvn clean install

“BUILD SUCCESS”之後，您可以在 target 目錄下找到 JAR 檔案。

對於 Gradle，您可以使用如下所示的命令：

gradle clean build

“BUILD SUCCESSFUL”之後，您可以在 build/libs 目錄下找到 JAR 檔案。

現在，使用以下命令執行 JAR 檔案：

java –jar <JARFILE>

您可以看到應用程式已在 Tomcat 埠 8080 上啟動。

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/

[32m :: Spring Boot :: [39m              [2m (v3.3.4)[0;39m

[2m2024-09-20T16:44:57.869+05:30[0;39m [32m INFO[0;39m [35m14684[0;39m [2m---[0;39m [2m[emailapp] [           main][0;39m [2m[0;39m[36mc.t.emailapp.EmailappApplication        [0;39m [2m:[0;39m Starting EmailappApplication using Java 21.0.3 with PID 14684 (E:\Dev\emailapp\target\classes started by Tutorialspoint in E:\Dev\emailapp)
[2m2024-09-20T16:44:57.872+05:30[0;39m [32m INFO[0;39m [35m14684[0;39m [2m---[0;39m [2m[emailapp] [           main][0;39m [2m[0;39m[36mc.t.emailapp.EmailappApplication        [0;39m [2m:[0;39m No active profile set, falling back to 1 default profile: "default"
[2m2024-09-20T16:44:58.799+05:30[0;39m [32m INFO[0;39m [35m14684[0;39m [2m---[0;39m [2m[emailapp] [           main][0;39m [2m[0;39m[36mo.s.b.w.embedded.tomcat.TomcatWebServer [0;39m [2m:[0;39m Tomcat initialized with port 8080 (http)
[2m2024-09-20T16:44:58.815+05:30[0;39m [32m INFO[0;39m [35m14684[0;39m [2m---[0;39m [2m[emailapp] [           main][0;39m [2m[0;39m[36mo.apache.catalina.core.StandardService  [0;39m [2m:[0;39m Starting service [Tomcat]
[2m2024-09-20T16:44:58.816+05:30[0;39m [32m INFO[0;39m [35m14684[0;39m [2m---[0;39m [2m[emailapp] [           main][0;39m [2m[0;39m[36mo.apache.catalina.core.StandardEngine   [0;39m [2m:[0;39m Starting Servlet engine: [Apache Tomcat/10.1.30]
[2m2024-09-20T16:44:58.873+05:30[0;39m [32m INFO[0;39m [35m14684[0;39m [2m---[0;39m [2m[emailapp] [           main][0;39m [2m[0;39m[36mo.a.c.c.C.[Tomcat].[localhost].[/]      [0;39m [2m:[0;39m Initializing Spring embedded WebApplicationContext
[2m2024-09-20T16:44:58.874+05:30[0;39m [32m INFO[0;39m [35m14684[0;39m [2m---[0;39m [2m[emailapp] [           main][0;39m [2m[0;39m[36mw.s.c.ServletWebServerApplicationContext[0;39m [2m:[0;39m Root WebApplicationContext: initialization completed in 948 ms
[2m2024-09-20T16:44:59.229+05:30[0;39m [32m INFO[0;39m [35m14684[0;39m [2m---[0;39m [2m[emailapp] [           main][0;39m [2m[0;39m[36mo.s.b.w.embedded.tomcat.TomcatWebServer [0;39m [2m:[0;39m Tomcat started on port 8080 (http) with context path '/'
[2m2024-09-20T16:44:59.238+05:30[0;39m [32m INFO[0;39m [35m14684[0;39m [2m---[0;39m [2m[emailapp] [           main][0;39m [2m[0;39m[36mc.t.emailapp.EmailappApplication        [0;39m [2m:[0;39m Started EmailappApplication in 1.818 seconds (process running for 2.696)

現在從您的 Web 瀏覽器訪問以下 URL，您將收到一封電子郵件。

https://:8080/sendemail

Email Sent Successfully Browser Window

Email Sent Successfully
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