java动态代理--代理接口无实现类

使用通过接口定义，或解析接口注解等完成相关功能，如mybatis的SqlSession.getMapper的实现

1.接口定义

package cn.proxy;

public interface IHello {
	String say(String aa);
}

2.代理实现

package cn.proxy;

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

/**
 *  JDK动态代理代理类 
 *
 */
@SuppressWarnings("unchecked")
public class FacadeProxy implements InvocationHandler {  
    @Override  
    public Object invoke(Object proxy, Method method, Object[] args)  
            throws Throwable {  
        System.out.println("接口方法调用开始");  
        //执行方法  
        System.out.println("method toGenericString:"+method.toGenericString());
        System.out.println("method name:"+method.getName());
        System.out.println("method args:"+(String)args[0]);
        System.out.println("接口方法调用结束");  
        return "调用返回值";  
    }  
	
	public static <T> T newMapperProxy(Class<T> mapperInterface) {
        ClassLoader classLoader = mapperInterface.getClassLoader();
        Class<?>[] interfaces = new Class[]{mapperInterface};
        FacadeProxy proxy = new FacadeProxy();
        return (T) Proxy.newProxyInstance(classLoader, interfaces, proxy);
      }
}

4.运行

package cn.proxy;

public class Test {
	public static void main(String[] args) {
		IHello hello = FacadeProxy.newMapperProxy(IHello.class);
		System.out.println(hello.say("hello world"));
	}
}

运行结果：

接口方法调用开始
method toGenericString:public abstract java.lang.String cn.proxy.IHello.say(java.lang.String)
method name:say
method args:hello world
接口方法调用结束
调用返回值