动态代理

Spring AOP使用了两种代理机制，一种是基于JDK的动态代理，另一种是基于CGLib的动态代理，之所以需要两种代理机制，很大程度上是因为JDK本身只提供基于接口的代理，不支持类的代理。

public interface ProxyInterface {

    void display();
}





public class RealObject implements ProxyInterface {

    @Override
    public void display() {
       
        System.out.println("I am  Real Object Method ");

    }

}


// ProxyRealObject  中间类

public class ProxyRealObject implements InvocationHandler {

    private  Object targetObject; // //代理对象直接用  real new创建  


    public ProxyRealObject(Object obj) {
        targetObject = obj;
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args)
            throws Throwable {
        //RealObject  object =  (RealObject)this.targetObject;
        Object  result ;
        System.out.println(" 方法前 ");
        result = method.invoke(targetObject, args); 
        System.out.println(" 方法后 ");
        return result;
    }
   
    public static void main(String[] args) {
        RealObject realobject   = new RealObject();
        InvocationHandler  handler  =  new ProxyRealObject(realobject);
         ProxyInterface  interface1   =  (ProxyInterface)Proxy.newProxyInstance(realobject.getClass().getClassLoader(), realobject.getClass().getInterfaces(), handler);
         interface1.display();
    }

}