Java代理：Proxy InvocationHandler

public interface IHelloWorld {

    void sayHello();

}

 

public class HelloWorldImpl implements IHelloWorld {

    public void sayHello() {
        System.out.println("Hello World!!");
    }

}

 

public class HelloWorldHandler implements InvocationHandler {

    IHelloWorld object;

    public HelloWorldHandler(IHelloWorld object) {
        this.object = object;
    }

    public Object invoke(Object proxy, Method method, Object[] args)
            throws Throwable {
        System.out.println("before");
        Object o = method.invoke(object, args);
        System.out.println("after");
        return o;
    }

}

 

public class proxyDemo {

    public static void main(String[] args) {
        InvocationHandler handler = new HelloWorldHandler(new HelloWorldImpl());
        IHelloWorld proxy = (IHelloWorld)Proxy.newProxyInstance(
                HelloWorldImpl.class.getClassLoader(),
                HelloWorldImpl.class.getInterfaces(),
                handler);
        proxy.sayHello();
    }

}

 

before
Hello World!!
after