jdk 动态代理

    动态代理在框架中使用较为普遍，是java的高层只是，本博文介绍jdk实现的动态代理。

1，jdk的动态代理，被代理类必须要实现一个接口。

package com.supan.jdkdynamicproxy;
public interface Person
{
  public void sayName();
  public void sayAge();
}

2，实现类1

package com.supan.jdkdynamicproxy;
public class ChinaPersonImpl implements Person
{
	@Override
	public void sayName()
	{
		System.out.println("my name is chenchaoyang， I came from China");
	}

	@Override
	public void sayAge()
	{
		System.out.println("I am 27, I came from China");
	}
}

实现类2

package com.supan.jdkdynamicproxy;
public class AmericanPersonImpl implements Person
{
	@Override
	public void sayName()
	{
		System.out.println("my name is chenchaoyang， I came from American");
	}

	@Override
	public void sayAge()
	{
		System.out.println("I am 27, I came from American");
	}
}

3，获取代理对象的类

package com.supan.jdkdynamicproxy;

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

public class PersonProxy implements InvocationHandler
{
	private Object target;

	@Override
	public Object invoke(Object proxy, Method method, Object[] args)
			throws Throwable
	{
		Object result = null;
		System.out.println("事物开始");
		result = method.invoke(target, args);
		System.out.println("事物结束");
		return result;
	}
	
	public Object bind(Object target)
	{
		this.target = target;
		
		return Proxy.newProxyInstance(target.getClass().getClassLoader(), target.getClass().getInterfaces(), this);
	}
}

4，测试类

package com.supan.jdkdynamicproxy;
public class TestJdkProxy
{
	public static void main(String[] args)
	{
		
       PersonProxy personProxy = new PersonProxy();
       Person chinaPerson = (Person)personProxy.bind(new ChinaPersonImpl());
       chinaPerson.sayName();
       chinaPerson.sayAge();
       
       Person americanPerson = (Person)personProxy.bind(new AmericanPersonImpl());
       americanPerson.sayName();
       americanPerson.sayAge();
	}

}

打印结果：
事物开始
my name is chenchaoyang， I came from China
事物结束
事物开始
I am 27, I came from China
事物结束
事物开始
my name is chenchaoyang， I came from American
事物结束
事物开始
I am 27, I came from American
事物结束