package com.vx.servicehi.annotation;

import java.lang.annotation.Annotation;

import java.lang.reflect.Method;

/**

* 解析注解

* 通过反射获取类，函数或成员上的运行时注解信息，从而实现动态控制程序运行的逻辑

*

* 对于一个类或者接口来说，Class 类中提供了以下一些方法用于反射注解。

getAnnotation：返回指定的注解

isAnnotationPresent：判定当前元素是否被指定注解修饰

getAnnotations：返回所有的注解

getDeclaredAnnotation：返回本元素的指定注解

getDeclaredAnnotations：返回本元素的所有注解，不包含父类继承而来的

*

* @author wangbs

* @date 2019-12-21 22:52:42

*

*/

public class ParseDecription {

public static void main(String[] args) {

// TODO Auto-generated method stub

// 1、使用类加载器加载类

try {

Class c = Class.forName("com.hd.TestRateLimiter");

System.out.println(c);

// 2、找到类上面的注解

boolean isExist = c.isAnnotationPresent(RateLimiter.class);

if(isExist) {

// 3、拿到注解实例

RateLimiter d = (RateLimiter) c.getAnnotation(RateLimiter.class);

System.out.println("========parse class annotation=========");

System.out.println("desc = " + d.key());

System.out.println("author = " + d.message());

System.out.println("age = " + d.limit());

}

// 4、找到方法上的注解

Method[] ms = c.getMethods();

for (Method m : ms) {

boolean isMExist = m.isAnnotationPresent(RateLimiter.class);

if(isMExist) {

RateLimiter d = m.getAnnotation(RateLimiter.class);

System.out.println("========parse method annotation=========");

System.out.println("desc = " + d.key());

System.out.println("author = " + d.message());

System.out.println("age = " + d.limit());

}

}

// 另外一种解析方法

for (Method m : ms) {

Annotation[] annotations = m.getAnnotations();

for (Annotation annotation : annotations) {

if(annotation instanceof RateLimiter) {

System.out.println("========parse method annotation other way=========");

RateLimiter d = (RateLimiter) annotation;

System.out.println("desc = " + d.key());

System.out.println("author = " + d.message());

System.out.println("age = " + d.limit());

}

}

}

} catch (ClassNotFoundException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

}