Spring的代理模式（静态代理和动态代理）

静态代理示例：

接口：

package com.yourcompany.spring1;

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

实现：

package com.yourcompany.spring1;

public class HelloImpl implements IHello{
	public void say(String name){
		System.out.println("Hello,"+name);
	}
}

静态代理：

package com.yourcompany.spring1;

import org.apache.log4j.Level;
import org.apache.log4j.Logger;

public class HelloProxy implements IHello {
	private Logger logger=Logger.getLogger(this.getClass().getName());
	private IHello hello;
	
	public HelloProxy(IHello hello){
		this.hello=hello;
	}
	public void say(String name) {
		//日志服务
		log("hello method starts....");
		//执行业务逻辑
		hello.say(name);		
		//日志服务
		log("hello method ends...");		
	}
	private void log(String msg){
		logger.log(Level.INFO, msg);
	}
}

程序主入口：

package com.yourcompany.spring1;

public class StaticProxy{
    public static void main(String[] args) {
	    IHello proxy=new HelloProxy(new HelloImpl());
		proxy.say("Lucy");
	}
}

动态代理示例：

接口：

package com.yourcompany.spring2;

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

实现：

package com.yourcompany.spring2;

public class HelloImpl implements IHello{
	public void say(String name){
		System.out.println("Hello,"+name);
	}
}

动态代理：

package com.yourcompany.spring2;

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

import org.apache.log4j.Level;
import org.apache.log4j.Logger;

public class HelloProxy implements InvocationHandler {
	private Logger logger=Logger.getLogger(this.getClass().getName());
	private Object targetObject;
	
	public Object newProxy(Object targetObject){
		this.targetObject = targetObject;
		return Proxy.newProxyInstance(targetObject.getClass().getClassLoader(),targetObject.getClass().getInterfaces(), this);
	}
	public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
		log("hello method starts....");
		//args是方法的参数
		Object ret =  method.invoke(targetObject, args);
		log("hello method ends...");		
		return ret;
	}
	private void log(String msg){
		logger.log(Level.INFO, msg);
	}
}

程序主入口：

package com.yourcompany.spring2;

import com.yourcompany.spring2.HelloProxy;

public class DynamicProxy{
    public static void main(String[] args) {
		HelloProxy helloProxy=new HelloProxy();	
		IHello hello=(IHello)helloProxy.newProxy(new HelloImpl());
		hello.say("Lucy");
	}
}

上面两示例都需要用到的Log4j配置log4j.properties：

log4j.rootLogger=INFO,stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] -%m%n