java简单的动态代理示例

1、定义一个接口Student，后面用于强转proxy实例类型

interface Student {
	public void study();
}

2、定义接口实现类StudentImpl

对象调用getClass().getClassLoader(), getClass().getInterfaces()，用于proxy实例参数

public class StudentImpl implements Student {

	public void study() {
		System.out.println("woaixuexi");

	}

}

3、定义自己的MyInvocationHandle实现InvocationHandler，在此定义所要增加的方法

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

public class MyInvocationHandle implements InvocationHandler {
	private Object handler;
	
	public MyInvocationHandle() {
		super();
	}

	
	public MyInvocationHandle(Object handler) {
		super();
		this.handler = handler;
	}

	public Object invoke(Object arg0, Method arg1, Object[] arg2)
			throws Throwable {
		System.out.println("xuexiqianchifan");
		Object result = arg1.invoke(handler, arg2);
		System.out.println("shuijiao");
		return result;
	}

}

4、测试类

new StudentImpl 对象，作为参数传入MyInvocationHandle，产生proxy实例，向下转型为Student，不能是StudentImpl

import java.lang.reflect.Proxy;

public class StudentTest {
	public static void main(String[] args) {
		StudentImpl st = new StudentImpl();
		MyInvocationHandle my = new MyInvocationHandle(st);
		Student p = (Student) Proxy.newProxyInstance(st.getClass().getClassLoader(), st.getClass().getInterfaces(), my);
		p.study();
	}
}