靜態代理&動態代理

原文地址：http://blog.csdn.net/partner4java/article/details/7048879

 

靜態AOP和動態AOP。 

靜態代理： 
代理對象與被代理對象必須實現同一個接口。 
demo：

package cn.partner4java.proxy.staticproxy;


/**
* 靜態代理，統一接口
* @author partner4java
*
*/
public interface IHello {
    /**
     * 能夠帶來的統一方法
     * @param name
     */
    public void hello(String name);
}

package cn.partner4java.proxy.staticproxy;

/**
* 被代理的對象，須要藉助代理對象加入日誌
* @author partner4java
*
*/
public class HelloSpeaker implements IHello {

    public void hello(String name) {
        System.out.println("Hello " + name);
    }

}

package cn.partner4java.proxy.staticproxy;

/**
* 代理對象，給被代理對象添加日誌
*/
public class HelloProxy implements IHello {

    private IHello iHello;

    public HelloProxy(IHello iHello) {
        super();
        this.iHello = iHello;
    }


    public void hello(String name) {
        System.out.println("記錄日誌");
        iHello.hello(name);
    }

}

package cn.partner4java.proxy.staticproxy;

/**
* 調用
* @author partner4java
*
*/
public class ProxyDemo {

    public static void main(String[] args) {
        IHello iHello = new HelloProxy(new HelloSpeaker());
        iHello.hello("long");
    }

}

動態代理： 
動態代理區別於靜態帶來實現的地方在於織入過程是在運行時動態進行的。本身實現通常實現java.lang.reflect.InvocationHandler接口。 
例子：

package cn.partner4java.proxy.dynamicproxy;


public interface IHello {
    public void hello(String name);
}

package cn.partner4java.proxy.dynamicproxy;

/**
* 被代理的對象，須要藉助代理對象加入日誌
* @author partner4java
*
*/
public class HelloSpeaker implements IHello {

    public void hello(String name) {
        System.out.println("Hello " + name);
    }

}

package cn.partner4java.proxy.dynamicproxy;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

/**
* 動態代理對象
* @author partner4java
*
*/
public class LogHandler implements InvocationHandler {

    private Object delegate;

    public Object bind(Object delegate){
        this.delegate = delegate;
        return Proxy.newProxyInstance(delegate.getClass().getClassLoader(),
                delegate.getClass().getInterfaces(), this);
    }
    /**
     * 代理對象，這裏面還能夠改變原有的方法
     */
    public Object invoke(Object proxy, Method method, Object[] args)
            throws Throwable {
        Object result = null;
        try {
            System.out.println("添加日誌");
            result = method.invoke(delegate, args);
        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }

}

package cn.partner4java.proxy.dynamicproxy;

/**
* 測試
* @author partner4java
*
*/
public class ProxyDemo {
    public static void main(String[] args) {
        LogHandler logHandler = new LogHandler();
        IHello iHello = (IHello) logHandler.bind(new HelloSpeaker());
        iHello.hello("long");
    }
}

------------------------------------------------------------------ 


利用ProxyFactory鏈接CGLIB簡單實現AOP： 
加入包aopalliance.jar\cglib-nodep-2.1_3.jar 
demo：

package cn.partner4java.proxy.proxyfactory;

/**
* 被代理的對象
* @author partner4java
*
*/
public class MessageWriter {
    public void writeMessage(){
        System.out.println("world!");
    }
}

package cn.partner4java.proxy.proxyfactory;

import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;

/**
* 裝飾者<br/>
* MethodInterceptor接口是對方法調用鏈接點實現包圍通知的AOP聯盟標準接口
* @author partner4java
*
*/
public class MessageDecorator implements MethodInterceptor{

    public Object invoke(MethodInvocation invocation) throws Throwable {
        System.out.print("Hello ");
        Object retVal = invocation.proceed();
        return retVal;
    }

}

package cn.partner4java.proxy.proxyfactory;

import org.springframework.aop.framework.ProxyFactory;

/**
* 調用組裝
* 這裏最重要的部分是咱們使用ProxyFactory來建立一個目標對象代理，同時織入通知
* @author partner4java
*
*/
public class HelloWorldWeaver {

    public static void main(String[] args) {
        //目標
        MessageWriter target = new MessageWriter();

        //create the proxy
        ProxyFactory proxyFactory = new ProxyFactory();

        proxyFactory.addAdvice(new MessageDecorator());
        proxyFactory.setTarget(target);

        //獲取返回被代理的目標
        MessageWriter proxy = (MessageWriter) proxyFactory.getProxy();

        target.writeMessage();
        System.out.println("---");
        proxy.writeMessage();
//      後臺打印：
//      world!
//      ---
//      World world!
    }

}