基于动态代理实现接口耗时计算

对于动态代理模式，Java的反射机制提供了支持。

耗时计算写在主逻辑代码存在很强的耦合性，这里提供了一种解耦合的方式去实现，在Spring框架aop也用了这一技术。

登录接口：

public class UserServiceImpl implements IUserService {


    public UserServiceImpl() {

    }


    @Override
    public LoginVo login() {
        //登录操作
        String token = "123";
        try {
            Thread.sleep(new Random().nextInt(100));
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("登录成功！");
        return new LoginVo(token);
    }
}

利用Proxy.newProxyInstance动态创建实现类

public class PrintUtil {

    public static Object createProxy(Object proxiedObject) {
        Class<?>[] interfaces = proxiedObject.getClass().getInterfaces();
        DynamicProxyHandler handler = new DynamicProxyHandler(proxiedObject);
        return Proxy.newProxyInstance(proxiedObject.getClass().getClassLoader(), interfaces, handler);
    }

    private static class DynamicProxyHandler implements InvocationHandler {
        private Object proxiedObject;

        public DynamicProxyHandler(Object proxiedObject) {
            this.proxiedObject = proxiedObject;
        }

        @Override
        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
            long startTimestamp = System.currentTimeMillis();
            Object result = method.invoke(proxiedObject, args);
            long endTimeStamp = System.currentTimeMillis();
            long responseTime = endTimeStamp - startTimestamp;
            String apiName = proxiedObject.getClass().getName() + ":" + method.getName();
            System.out.println("apiName: " + apiName + "\nneedTime: " + responseTime + " ms");
            return result;
        }
    }
}

上层调用。

public class UserController {
    IUserService userService = (IUserService)PrintUtil.createProxy(new UserServiceImpl());

    public Object handle(){
        return userService.login();
    }
}

测试结果：

public class Test {
    public static void main(String[] args) {
        UserController controller = new UserController();
        final Object res = controller.handle();
    }
}


登录成功！
apiName: com.cx.learn.model.proxy.UserServiceImpl:login
needTime: 76 ms