Spring AOP 入门范例

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：

Java代码 ?

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

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

Spring中的TestAction配置：

Java代码 ?

1. <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：

Java代码 ?

1. public?String?test()?throws?Exception{? ??
2. ??????return?"success";??? ??
3. }??

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：

Java代码 ?

1. <?xml?version="1.0"?encoding="UTF-8"?> ??
2. ??
3. <beans?xmlns="http://www.springframework.org/schema/beans"??
4. ?????????xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"??
5. ?????????xmlns:aop="http://www.springframework.org/schema/aop"??
6. ?????????xmlns:tx="http://www.springframework.org/schema/tx"??
7. ?????????xsi:schemaLocation="http://www.springframework.org/schema/beans?http://www.springframework.org/schema/beans/spring-beans-2.0.xsd ??
8. ???????????http://www.springframework.org/schema/aop?http://www.springframework.org/schema/aop/spring-aop-2.0.xsd ??
9. ???????????http://www.springframework.org/schema/tx?http://www.springframework.org/schema/tx/spring-tx-2.0.xsd"> ??
10. ? ??
11. ??
12. ?????<bean?id="testAction"?class="test.TestAction"/> ??
13. ????? ??
14. ?????<!--?定义通知?--> ??
15. ?????<bean?id="loginCheck"?class="aop.LoginCheck"?scope="prototype"/>? ??
16. ????? ??
17. ?????<!--定义Advisor,即Spring中的切面(由通知和切入点组成)--> ??
18. ?????<bean?id="loginAdvisor"?class="org.springframework.aop.support.NameMatchMethodPointcutAdvisor"> ??
19. ?????????<property?name="advice"?ref="loginCheck"></property> ??
20. ?????????<property?name="mappedNames"> ??
21. ????????????<list>?? ??
22. ????????????????<!--?需要被拦截的方法名,为了清除显示, ??
23. ???????????????通过在struts.xml文件中设置method选项,来避免execute方法名?--> ??
24. ???????????????<value>test</value>?? ??
25. ????????????</list> ??
26. ????????</property>? ??
27. ?????</bean>? ??
28. ????????? ??
29. ?????<bean?class="org.springframework.aop.framework.autoproxy.BeanNameAutoProxyCreator"> ??
30. ????????<property?name="beanNames"> ??
31. ???????????<list> ??
32. ????????????????<!--?需要被拦截的bean的名称?-->?? ??
33. ????????????????<value>testAction</value>?? ??
34. ???????????</list> ??
35. ????????</property> ??
36. ????????<property?name="interceptorNames"> ??
37. ????????????<list> ??
38. ???????????????<value>loginAdvisor</value>?? ??
39. ????????????</list> ??
40. ????????</property> ??
41. ?????</bean> ??
42. ??
43. </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：

Java代码 ?

1. public?class?LoginCheck?implements?MethodInterceptor{ ??
2. ??
3. ????public?Object?invoke(MethodInvocation?invocation)?throws?Throwable?{ ??
4. ????????HttpSession?session?=?ServletActionContext.getRequest().getSession(); ??
5. ????????Object?obj?=?session.getAttribute("loginuser"); ??
6. ????????if(obj==null){ ??
7. ????????????throw?new?NoLoginException("您还没有登录!!!");?? ??
8. ????????} ??
9. ????????return?invocation.proceed();???????? ??
10. ????} ??
11. ??
12. }??

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：

Java代码 ?

1. <error-page> ??
2. ?????<exception-type>exception.NoLoginException</exception-type> ??
3. ?????<location>/error.jsp</location> ??
4. </error-page>??