spring method interceptor
-author: leisure.xu
首先dao里面有find和save方法，本实例以拦截find方法为主，并改变find的返回值。
package com.leisure;
public class Dao {
public String find() {
System. out.println( "dao: find()");
return "student";
}
public void save() {
System. out.println( "dao: save()");
}
}
一、新增一个DaoInterceptor,如下
package com.leisure;
import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;
/**
* class description goes here
* @author leisure.xu
* @version 1.0.0, 2012 -6 -29
*/
public class DaoInterceptor implements MethodInterceptor {
@Override
public Object invoke(MethodInvocation invocation) throws Throwable {
String methodName = invocation.getMethod().getName();
if( "find".equals(methodName)) {
System. out.println( "invocation modify the return result to 'teacher'");
return "teacher";
}
return invocation.proceed();
}
}
DaoInterceptor实现了MethodInterceptor的invoke方法，在这里，MethodInvocation参数可以获取到getArguments等数据，至于能做什么，你懂的。
二、Dao跟DaoInterceptor还是没扯上关系，这时需要修改applicationContext.xml
原来：
<bean id = "dao" class= "com.leisure.Dao"/>
修改为：
<!--
<bean id=" dao" class="com.leiusre.Dao"/>
-->
<bean id ="daoInterceptor" class="com.leisure.DaoInterceptor"/>
<bean id ="dao" class= "org.springframework.aop.framework.ProxyFactoryBean" >
<property name ="target">
<bean class ="com.leisure.Dao" />
</property >
<property name ="interceptorNames">
<list >
<value >daoInterceptor </value >
</list >
</property >
</bean >
三、运行看效果！
ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml" );
Dao dao = context.getBean(Dao. class);
System. out.println(dao.find());
dao.save();
结果：
invocation modify the return result to 'teacher'
teacher
dao: save()
从结果可以看出invocation拦截了find方法，并且修改了其返回结果，而对象的find方法并没有执行到。
该实例引用到的jar包：
