Spring 整合Struts2(xml配置bean)

【1】添加Spring和Struts2需要的jar包，尤其是整合jar包​​struts2-spring-plugin-2.3.16.jar​​不可缺少；

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【2】配置applicationContext.xml

正常配置XML，其中，如果在xml中配置Action，需注意scope属性一定为prototype。

基于xml方式配置controller、service

<!-- stuts2 的action实例非单例，一定要加上域属性(默认为单例模式) -->
    <bean id="personAction" class="com.struts2.actions.PersonAction" scope="prototype">
        <property name="personService" ref="personService"></property>
    </bean>

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【3】配置web.xml

配置Struts2核心过滤器、Spring初始化容器监听器等。

<!-- ***Spring IOC 容器初始化*** -->
  <context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>classpath:applicationContext.xml</param-value>
  </context-param>

  <listener>
    <listener-class>
        org.springframework.web.context.ContextLoaderListener
    </listener-class>
  </listener>


  <!-- *********Spring的字符编码过滤器*****************-->
    <filter>
        <filter-name>encoding</filter-name>
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>UTF-8</param-value>
        </init-param>
        <init-param>  
            <param-name>forceEncoding</param-name>  
            <param-value>true</param-value>  
        </init-param> 
    </filter>
    <filter-mapping>
        <filter-name>encoding</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

    <!-- ******Struts2核心过滤器*****  -->
     <filter>
        <filter-name>struts2</filter-name>
        <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
    </filter>

    <filter-mapping>
        <filter-name>struts2</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

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【4】配置struts.xml

注意此时，Action里面class属性为Sping配置文件中的bean-Id（如果使用注解，则为注解时配置的名字）；

<package name="default" extends="struts-default" namespace="/">
        <!-- name reference action exclude '.action' -->
        <action name="person-save" class="personAction" >
            <result>/success.jsp</result>
        </action>
</package>

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【5】实现原理

• Struts2有自己默认对象池：

<bean class="com.opensymphony.xwork2.ObjectFactory" name="struts"/>

源码：

public Object buildBean(String className, Map<String, Object> extraContext) throws Exception {
        return buildBean(className, extraContext, true);
    }

    /**
     * Build a generic Java object of the given type.
     *
     * @param className the type of Object to build
     * @param extraContext a Map of extra context which uses the same keys as the {@link com.opensymphony.xwork2.ActionContext}
     */
    public Object buildBean(String className, Map<String, Object> extraContext, boolean injectInternal) throws Exception {
        Class clazz = getClassInstance(className);
        Object obj = buildBean(clazz, extraContext);
        /*通过反射创建bean*/
        if (injectInternal) {
            injectInternalBeans(obj);
        }
        return obj;
    }

• struts-plugin.xml 中重新修改了默认对象池：

<bean type="com.opensymphony.xwork2.ObjectFactory" name="spring" class="org.apache.struts2.spring.StrutsSpringObjectFactory" />

    <!--  Make the Spring object factory the automatic default -->
    <constant name="struts.objectFactory" value="spring" />

SpringObjectFactory（StrutsSpringObjectFactor的父类）源码：

@Override
    public Object buildBean(String beanName, Map<String, Object> extraContext, boolean injectInternal) throws Exception {
        Object o;

        if (appContext.containsBean(beanName)) {
            o = appContext.getBean(beanName);
            //首先通过IOC容器获取bean
        } else {
            Class beanClazz = getClassInstance(beanName);
            o = buildBean(beanClazz, extraContext);
            //其次，若获取不到，则通过反射构建bean
        }
        if (injectInternal) {
            injectInternalBeans(o);
        }
        return o;
    }