JSF - Spring整合

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Spring 提供了一個特殊的類 `DelegatingVariableResolver`，以無縫的方式將 JSF 和 Spring 整合在一起。

將 Spring 依賴注入 (IOC) 功能整合到 JSF 中需要以下步驟。

步驟 1：新增 `DelegatingVariableResolver`

在 `faces-config.xml` 中新增一個變數解析器條目，指向 Spring 類 `DelegatingVariableResolver`。

<faces-config>
   <application>
   <variable-resolver>
      org.springframework.web.jsf.DelegatingVariableResolver
   </variable-resolver>
   ...
</faces-config>

步驟 2：新增上下文監聽器

在 `web.xml` 中新增 Spring 框架提供的 `ContextLoaderListener` 和 `RequestContextListener` 監聽器。

<web-app>
   ...
   <!-- Add Support for Spring -->
   <listener>
      <listener-class>
         org.springframework.web.context.ContextLoaderListener
      </listener-class>
   </listener>
   
   <listener>
      <listener-class>
         org.springframework.web.context.request.RequestContextListener
      </listener-class>
   </listener>
   ...
</web-app>

步驟 3：定義依賴項

在 `applicationContext.xml` 中定義將在託管 Bean 中用作依賴項的 Bean。

<beans>
   <bean id = "messageService" 
      class = "com.tutorialspoint.test.MessageServiceImpl">
      <property name = "message" value = "Hello World!" />        
   </bean>
</beans>

步驟 4：新增依賴項

`DelegatingVariableResolver` 首先將值查詢委託給 JSF 的預設解析器，然後委託給 Spring 的 `WebApplicationContext`。這允許輕鬆地將基於 Spring 的依賴項注入到 JSF 託管 Bean 中。

這裡我們將 `messageService` 注入為基於 Spring 的依賴項。

<faces-config>
   ...
   <managed-bean>
      <managed-bean-name>userData</managed-bean-name>
      <managed-bean-class>com.tutorialspoint.test.UserData</managed-bean-class>
      <managed-bean-scope>request</managed-bean-scope>
      
      <managed-property>
         <property-name>messageService</property-name>
         <value>#{messageService}</value>
      </managed-property>
   </managed-bean> 
</faces-config>

步驟 5：使用依賴項

//jsf managed bean
public class UserData {
   
   //spring managed dependency
   private MessageService messageService;

   public void setMessageService(MessageService messageService) {
      this.messageService = messageService;
   }

   public String getGreetingMessage() {
      return messageService.getGreetingMessage();
   }
}

示例應用程式

讓我們建立一個測試 JSF 應用程式來測試 Spring 整合。

pom.xml

<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.test</groupId>
   <artifactId>helloworld</artifactId>
   <packaging>war</packaging>
   <version>1.0-SNAPSHOT</version>
   <name>helloworld Maven Webapp</name>
   <url>http://maven.apache.org</url>
   
   <dependencies>
      <dependency>
         <groupId>junit</groupId>
         <artifactId>junit</artifactId>
         <version>3.8.1</version>
         <scope>test</scope>
      </dependency>
      
      <dependency>
         <groupId>com.sun.faces</groupId>
         <artifactId>jsf-api</artifactId>
         <version>2.1.7</version>
      </dependency>
      
      <dependency>
         <groupId>com.sun.faces</groupId>
         <artifactId>jsf-impl</artifactId>
         <version>2.1.7</version>
      </dependency>
      
      <dependency>
         <groupId>javax.servlet</groupId>
         <artifactId>jstl</artifactId>
         <version>1.2</version>
      </dependency>
      
      <dependency>
         <groupId>org.springframework</groupId>
         <artifactId>spring-core</artifactId>
         <version>3.1.2.RELEASE</version>
      </dependency>
      
      <dependency>
         <groupId>org.springframework</groupId>
         <artifactId>spring-web</artifactId>
         <version>3.1.2.RELEASE</version> 
      </dependency>
   </dependencies>
   
   <build>
      <finalName>helloworld</finalName>
      <plugins>
         <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>2.3.1</version>
            <configuration>
               <source>1.6</source>
               <target>1.6</target>
            </configuration>
         </plugin>
         
         <plugin>
            <artifactId>maven-resources-plugin</artifactId>
            <version>2.6</version>
            
            <executions>
               <execution>
                  <id>copy-resources</id>
                  <phase>validate</phase>
                  <goals>
                     <goal>copy-resources</goal>
                  </goals>
                  
                  <configuration>
                     <outputDirectory>${basedir}/target/helloworld/resources
                        </outputDirectory>
                     <resources>          
                        <resource>
                           <directory>src/main/resources</directory>
                           <filtering>true</filtering>
                        </resource>
                     </resources>              
                  </configuration>            
               </execution>
            </executions>
         
         </plugin>
      </plugins>
   </build>
</project>

faces-config.xml

<?xml version = "1.0" encoding = "UTF-8"?>
<faces-config
   xmlns = "http://java.sun.com/xml/ns/javaee"
   xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation = "http://java.sun.com/xml/ns/javaee 
   http://java.sun.com/xml/ns/javaee/web-facesconfig_2_0.xsd"
   version = "2.0"> 
   
   <application>
      <variable-resolver>
         org.springframework.web.jsf.DelegatingVariableResolver
      </variable-resolver>
   </application>
   
   <managed-bean>
      <managed-bean-name>userData</managed-bean-name>
      <managed-bean-class>com.tutorialspoint.test.UserData</managed-bean-class>
      <managed-bean-scope>request</managed-bean-scope>
      <managed-property>
         <property-name>messageService</property-name>
         <value>#{messageService}</value>
      </managed-property>
   </managed-bean> 
</faces-config>

web.xml

<!DOCTYPE web-app PUBLIC
   "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
   "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
   <display-name>Archetype Created Web Application</display-name>

   <context-param>
      <param-name>javax.faces.PROJECT_STAGE</param-name>
      <param-value>Development</param-value>
   </context-param>	
   
   <!-- Add Support for Spring -->
   <listener> 
      <listener-class>
         org.springframework.web.context.ContextLoaderListener
      </listener-class>
   </listener>
   
   <listener>
      <listener-class>
         org.springframework.web.context.request.RequestContextListener
      </listener-class>
   </listener>
   
   <servlet>
      <servlet-name>Faces Servlet</servlet-name>
      <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
   </servlet>
   
   <servlet-mapping>
      <servlet-name>Faces Servlet</servlet-name>
      <url-pattern>*.jsf</url-pattern>
   </servlet-mapping>
</web-app>

applicationContext.xml

<?xml version = "1.0" encoding = "UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN 2.0//EN" 
   "http://www.springframework.org/dtd/spring-beans-2.0.dtd">

<beans>
   <bean id = "messageService" 
      class = "com.tutorialspoint.test.MessageServiceImpl">
      <property name = "message" value = "Hello World!" />        
   </bean>
</beans>

MessageService.java

package com.tutorialspoint.test;

public interface MessageService {
   String getGreetingMessage();
}

MessageServiceImpl.java

package com.tutorialspoint.test;

public class MessageServiceImpl implements MessageService {
   private String message;
   
   public String getGreetingMessage() {
      return message;
   }
   
   public String getMessage() {
      return message;
   }
   public void setMessage(String message) {
      this.message = message;
   }
}

UserData.java

package com.tutorialspoint.test;

import java.io.Serializable;

public class UserData implements Serializable {

   private static final long serialVersionUID = 1L;
	private MessageService messageService;

   public MessageService getMessageService() {
      return messageService;
   }

   public void setMessageService(MessageService messageService) {
      this.messageService = messageService;
   }

   public String getGreetingMessage() {
      return messageService.getGreetingMessage();
   }
}

home.xhtml

<?xml version = "1.0" encoding = "UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns = "http://www.w3.org/1999/xhtml"
   xmlns:f = "http://java.sun.com/jsf/core"    
   xmlns:h = "http://java.sun.com/jsf/html">
   
   <h:head>
      <title>JSF Tutorial!</title>
   </h:head>
   
   <h:body>
      <h2>Spring Integration Example</h2>
      #{userData.greetingMessage}
   </h:body>
</html> 

完成所有更改後，讓我們像在《JSF - 第一個應用程式》章節中那樣編譯並執行應用程式。如果應用程式一切正常，則會產生以下結果。