反射 动态代理

目标: 利用反射 动态代理

Counter 接口

public interface Counter {
    int add(int a,int b);
    int sub(int a,int b);
}

Counter 实现类

public class CounterImpl implements Counter {
    //方法为切入点
    @Override
    public int add(int a, int b) {
        System.out.println(a + b);
        return a + b;
    }

    @Override
    public int sub(int a, int b) {
        System.out.println(a - b);
        return a - b;
    }
}

测试类

public class ClassTest {
    public static void main(String[] args) {
        /**
         * 目标 : java JDK  的动态代理就是一个
         * 泛型的 反射封装
         */


        ClassLoader classLoader = ClassTest.class.getClassLoader();
        Class[] cl = {
                Counter.class
        };

        class MyInvocationHandler implements InvocationHandler {
            T t;

            public MyInvocationHandler(T t) {
                this.t = t;
            }

            @Override
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                System.out.println("前置方法");
                Object invoke = method.invoke(t, args);
                System.out.println("后置方法");
                return invoke;
            }
        }
        Counter o = (Counter) Proxy.newProxyInstance(
                classLoader, cl, new MyInvocationHandler(new CounterImpl())
        );

        o.add(1,1);
    }
}