代理的模式

代理的模式

应用场景：自己不想做，想让别人帮忙做自己的事情，甚至想让别人做的更好

静态代理

代理者和被代理者都需要实现接口，让代理者来做事情

public class MyProxyExt {

    interface IBuild{
        void create();
    }

    static class BuildImpl implements IBuild{
        @Override
        public void create() {
            System.out.println("修建房子");
        }
    }

    static class BuildProxy implements IBuild{
        private BuildImpl build ;

        public BuildProxy(BuildImpl build) {
            this.build = build;
        }

        @Override
        public void create() {
            build.create();
            System.out.println("修建泳池");
        }
    }

    public static void main(String[] args) {
        IBuild build = new BuildProxy(new BuildImpl()) ;
        build.create();
    }
}

动态代理

 只有被代理对象实现接口

 1.既然需要他人帮忙，那就要找到代理对象

 2.其次就是要对方做事情，调用方法

解决这两个问题，分别需要Proxy和  InvocationHandler

public class MyProxy {

    interface IBuild{
        void create();
    }

    static class BuildImpl implements IBuild{

        @Override
        public void create() {
            System.out.println("修建房子");
        }
    }

      class BuildHandler implements InvocationHandler{
        private Object object ;

        public BuildHandler(Object object) {
            this.object = object;
        }

        @Override
        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
            return  method.invoke(object,args) ;
        }
    }

    class BuildProxy {
        public  Object getInstance(Object object){
            BuildHandler buildHandler = new BuildHandler(object) ;
           return Proxy.newProxyInstance(object.getClass().getClassLoader() , object.getClass().getInterfaces(),buildHandler) ;
        }
    }


}

测试

public class Test {
    public static void main(String[] args) {
        MyProxy.IBuild build = new MyProxy.BuildImpl();
        MyProxy.IBuild buildProxy = (MyProxy.IBuild) new MyProxy(). new BuildProxy().getInstance(build);
        buildProxy.create();
    }
}