动态代理

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1接口

public interface ArithmeticCaculator {

    int add(int a, int b);

    int sub(int a, int b);

}

2.实现类

public class ArithmeticCaculatorImpl implements ArithmeticCaculator {

   @Override
   public int add(int a, int b) {
       return a + b;
   }

   @Override
   public int sub(int a, int b) {
       return a - b;
   }

}

3.代理类

public class AritmethticCaculatorProxy {

   // 要代理的目标对象
   ArithmeticCaculator target;

   public AritmethticCaculatorProxy(ArithmeticCaculator target) {
       this.target = target;
   }

   public ArithmeticCaculator proxy() {
       ClassLoader loader = target.getClass().getClassLoader(); // 代理对象由哪个类加载器加载
       Class<?>[] interfaces = target.getClass().getInterfaces(); // 代理对象所实现的接口

       InvocationHandler invocationHandler = new InvocationHandler() {// 代理对象调用其中的方法时，執行該代碼

           @Override
           public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
               System.out.println("before:" + Arrays.asList(args));
               Object result = method.invoke(target, args);
               System.out.println("result:" + result);
               return result;
           }
       };
       return (ArithmeticCaculator) Proxy.newProxyInstance(loader, interfaces, invocationHandler);
   }
}

4.测试

public class ceshi {
   public static void main(String[] args) throws Exception {
       ArithmeticCaculator arithmeticCaculator =new ArithmeticCaculatorImpl();
       AritmethticCaculatorProxy Proxy =new AritmethticCaculatorProxy(arithmeticCaculator );
       ArithmeticCaculator target =Proxy.proxy();
       target.add(1, 2);
   }
}

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