Java动态代理

Java动态代理：

 

一、代理模式

 

 

二、代理实现方式

1、被代理对象

 

public interface Target {
	
	public void doSomething();
	
	public void doOtherthing();

}

 

public class TargetImpl implements Target {

	@Override
	public void doSomething() {
		System.out.println("doing someting");
	}

	@Override
	public void doOtherthing() {
		System.out.println("doing otherthing");
	}
}

 

2、拦截器

public interface Interceptor {
	
	public void before();
	
	public void after();
}

 

public class TargetInterceptor implements Interceptor {

	@Override
	public void after() {
		System.out.println("after");
	}

	@Override
	public void before() {
		System.out.println("before");
	}
}

 

3、拦截器和被代理类的粘合剂

public class TargetHandler implements InvocationHandler {
	
	private Interceptor interceptor;
	
	private Object target;
	
	public void setInterceptor(Interceptor interceptor)
	{
		this.interceptor = interceptor;
	}
	
	public void setTarget(Object target)
	{
		this.target = target;
	}

	@Override
	public Object invoke(Object proxy, Method method, Object[] args)
			throws Throwable 
	{
		interceptor.before();
		Object result = method.invoke(target, args);
		interceptor.after();
		return result;
	}
}

 

4、动态代理类

public class DProxy {

	TargetHandler h = new TargetHandler();	

	public Object createDProxy(Object target, Interceptor interceptor) {
		
		h.setTarget(target);
		h.setInterceptor(interceptor);
		
		return Proxy.newProxyInstance(Target.class.getClassLoader(), target
				.getClass().getInterfaces(), h);
	}
}

 

5、测试代码

public class TestInterceptor {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		Target target = new TargetImpl();
		Interceptor interceptor = new TargetInterceptor();
		DProxy p = new DProxy();
		Target ptarget = (Target)p.createDProxy(target, interceptor);
		ptarget.doSomething();
		ptarget.doOtherthing();
	}
}