JDK 动态代理 & AOP实现动态代理

jdk动态代理

1. 动态代理是代理被代理的那个类，那么被代理的那个类是Object Taget，就是说他能替那个类添加函数啥的。

2. 代理的那个类里必须有Target的引用，代理的类必须实现jdk里的InvocationHandler接口，它能帮助我们添加方法。

3. 产生代理的类 Proxy.newProxyInstance后，其实代理类和被代理的类里 都有那个共有的接口，所以被代理的类也能访问那个接口的方法。

4. 用动态代理的话，方法执行前后动态的添加 我们需要的方法。这就是动态代理的好处。

 

IHello.java

package com.aspn.proxy; public interface IHello { public void toHello(String name); }

HelloImp

package com.aspn.proxy; public class HelloImp implements IHello { public void toHello(String name) { System.out.println("hello:" + name); } }

LogHandler.java

package com.aspn.proxy; import java.lang.reflect.InvocationHandler; import java.lang.reflect.Method; import java.lang.reflect.Proxy; public class LogHandler implements InvocationHandler { private Object deledate; public Object bind(Object deledate){ this.deledate = deledate; return Proxy.newProxyInstance(deledate.getClass().getClassLoader(), new Class[]{IHello.class}//同等 deledate.getClass().getInterfaces() , this); } public Object invoke(Object proxy, Method method, Object[] obj) throws Throwable { doBefore(); Object result = method.invoke(deledate, obj); doAfter(); return result; } private void doBefore() { System.out.println("before...."); } private void doAfter() { System.out.println("after...."); } }

ProxyDemo.java

package com.aspn.proxy; public class ProxyDemo { public static void main(String[] args) throws SecurityException, NoSuchMethodException { LogHandler logHandler = new LogHandler(); IHello hello = (IHello) logHandler.bind(new HelloImp()); hello.toHello("callan"); } }

 

上面的改成 Spring AOP的动态代理

 

IHello不变

 package com.aspn.proxy; public interface IHello { public void toHello(String name); }

HelloImp

package com.aspn.proxy; import org.springframework.stereotype.Component; @Component //默认就取类的第一个字母， 变成小写 public class HelloImp implements IHello { public void toHello(String name) { System.out.println("hello:" + name); } }

LogHandler.java

package com.aspn.proxy; import org.aspectj.lang.annotation.After; import org.aspectj.lang.annotation.Aspect; import org.aspectj.lang.annotation.Before; import org.springframework.stereotype.Component; @Aspect @Component public class LogHandler { @Before("execution(public void com.aspn.proxy.HelloImp.toHello(java.lang.String))")//执行这个方法之前添加下面的方法 public void befor(){ System.out.println("before............."); } @After("execution(public void com.aspn.proxy.HelloImp.toHello(java.lang.String))") public void ater(){ System.out.println("after............"); } }

ProxyDemo.java

package com.aspn.proxy; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class ProxyDemo { public static void main(String[] args) throws SecurityException, NoSuchMethodException { ApplicationContext factory = new ClassPathXmlApplicationContext("bean.xml"); IHello hello = (IHello) factory.getBean("helloImp"); hello.toHello("aaa"); } }

bean.xml

<?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:context="http://www.springframework.org/schema/context" xmlns:aop="http://www.springframework.org/schema/aop" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd"> <aop:aspectj-autoproxy></aop:aspectj-autoproxy> <context:component-scan base-package="com.aspn.*"></context:component-scan> </beans>

这里的<context:component-scan base-package="com.aspn.*">起着 代码里把类当成component的作用。

 

 

 

注意 1. MyEclipse里 Preferences里的 Xml catalog里添加相应的catalog

       2. 加入jar包，context,aspectJ里的两个包。

 

spring帮助文档是 spring-framework-2.5.6/docs/reference/html_single/index.html