动态代理

public interface ISinger {
public void single();

}

public class Singer implements ISinger {
@Override
public void single() {
System.out.println("唱一首歌");
}

}

public class DynamicProxy implements InvocationHandler {
private Object single;
public DynamicProxy(Object single) {
this.single = single;
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
System.out.println("向观众问好");
method.invoke(single, args);
System.out.println("谢谢大家");
return null;
}

}

public class Test {
public static void main(String[] args) {
ISinger singer = new Singer();
InvocationHandler hander = new DynamicProxy(singer);

ISinger iSinger = (ISinger) Proxy.newProxyInstance(hander.getClass().getClassLoader(),                                                                                             singer.getClass().getInterfaces(), 

                                                                           hander);

iSinger.single();
}
}