Spring AOP 入门实例

以Struts2+Spring为例,要求必须在登录之后才能实现某一链接。如果未登录则抛出异常,跳转到异常页面。

假设链接为：http://localhost:8080/aop/test.action

Struts2的配置文件struts.xml文件：

<action name="test" class="testAction" method="test">
       <result name="success">/succ.jsp</result>
</action>

<action name="test" class="testAction" method="test">
      <result name="success">/succ.jsp</result>
</action>

Spring中的TestAction配置：

<bean id="testAction" class="action.TestAction"/>

<bean id="testAction" class="action.TestAction"/>

TestAction类中的test方法只是实现简单的跳转,不需要考虑是否登录问题：

public String test() throws Exception{
       return "success";
}

public String test() throws Exception{ 
      return "success";   
}

此时点击链接能够跳转到succ.jsp。

加入登录检查

在applicationContext.xml文件中：

<?xml version="1.0" encoding="UTF-8"?>

 <beans xmlns="http://www.springframework.org/schema/beans"
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xmlns:aop="http://www.springframework.org/schema/aop"
          xmlns:tx="http://www.springframework.org/schema/tx"
          xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd
            http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.0.xsd
            http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.0.xsd">


      <bean id="testAction" class="test.TestAction"/>

     <!-- 定义通知 -->
      <bean id="loginCheck" class="aop.LoginCheck" scope="prototype"/>

     <!--定义Advisor,即Spring中的切面(由通知和切入点组成)-->
      <bean id="loginAdvisor" class="org.springframework.aop.support.NameMatchMethodPointcutAdvisor">
          <property name="advice" ref="loginCheck"></property>
          <property name="mappedNames">
            <list>
                <!-- 需要被拦截的方法名,为了清除显示,
               通过在struts.xml文件中设置method选项,来避免execute方法名 -->
               <value>test</value>
            </list>
        </property>
     </bean>

      <bean class="org.springframework.aop.framework.autoproxy.BeanNameAutoProxyCreator">
         <property name="beanNames">
           <list>
                <!-- 需要被拦截的bean的名称 -->
                <value>testAction</value>
           </list>
        </property>
         <property name="interceptorNames">
            <list>
               <value>loginAdvisor</value>
            </list>
        </property>
     </bean>

</beans>

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"
	     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	     xmlns:aop="http://www.springframework.org/schema/aop"
	     xmlns:tx="http://www.springframework.org/schema/tx"
	     xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd
           http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.0.xsd
           http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.0.xsd">
 

     <bean id="testAction" class="test.TestAction"/>
     
     <!-- 定义通知 -->
     <bean id="loginCheck" class="aop.LoginCheck" scope="prototype"/> 
     
     <!--定义Advisor,即Spring中的切面(由通知和切入点组成)-->
     <bean id="loginAdvisor" class="org.springframework.aop.support.NameMatchMethodPointcutAdvisor">
         <property name="advice" ref="loginCheck"></property>
         <property name="mappedNames">
            <list>  
                <!-- 需要被拦截的方法名,为了清除显示,
               通过在struts.xml文件中设置method选项,来避免execute方法名 -->
               <value>test</value>  
            </list>
        </property> 
     </bean> 
         
     <bean class="org.springframework.aop.framework.autoproxy.BeanNameAutoProxyCreator">
        <property name="beanNames">
           <list>
                <!-- 需要被拦截的bean的名称 -->  
                <value>testAction</value>  
           </list>
        </property>
        <property name="interceptorNames">
            <list>
               <value>loginAdvisor</value>  
            </list>
        </property>
     </bean>

</beans>

LoginCheck类：

public class LoginCheck implements MethodInterceptor{

     public Object invoke(MethodInvocation invocation) throws Throwable {
        HttpSession session = ServletActionContext.getRequest().getSession();
         Object obj = session.getAttribute("loginuser");
         if(obj==null){
             throw new NoLoginException("您还没有登录!!!");
        }
         return invocation.proceed();
    }

}

public class LoginCheck implements MethodInterceptor{

	public Object invoke(MethodInvocation invocation) throws Throwable {
		HttpSession session = ServletActionContext.getRequest().getSession();
		Object obj = session.getAttribute("loginuser");
		if(obj==null){
			throw new NoLoginException("您还没有登录!!!");  
		}
		return invocation.proceed();		
	}

}

为了在抛出NoLoginException异常时能够跳转到相关页面,可以在web.xml中设置：

<error-page>
     <exception-type>exception.NoLoginException</exception-type>
     <location>/error.jsp</location>
</error-page>