手写jvm内置缓存

用HashMap封装一个内置缓存：

开楼吧：

首先搭个框架：

SpringBoot+Mybatis

 然后编写内置缓存：

public class JvmMapCacheUtils {

    
    private static Map caches = new ConcurrentHashMap<>();

    
       public static  List listEntity(String key, Class t){
           //return JSONObject.parseObject(caches.get(key),t);
           return JSONObject.parseArray(caches.get(key),t);
       }



    
    public static void put(String key,Object o){
           caches.put(key,JSONObject.toJSonString(o));
       }


    
     public static  T getEntity(String key, Class t){
         return JSONObject.parseObject(caches.get(key),t);
     }



}

我们来测试下：

 
    @PostMapping("/listUser")
    public ResponseMessage listUser(HttpServletRequest request){
        ResponseMessage responseMessage = new ResponseMessage(0);
        try{
            String token = request.getHeader("token");
            logger.info("token的值:【{}】"+token);
            List user = null;
            user =  JvmMapCacheUtils.listEntity(token, User.class);
            //如果等于空
            if(StringUtils.isEmpty(user)){
                //模拟耗时时间
                Thread.sleep(1000);
                JvmMapCacheUtils.put(token,userService.getUser());
                responseMessage.setMessage(userService.getUser());
            }else {
                responseMessage.setMessage(user);
            }
        }catch (Exception ex){
            logger.error("查询用户信息信息异常", ex);
            throw new RuntimeException(ex.getMessage());
        }
        return responseMessage;
    }

走数据库耗时1270毫秒多

 走缓存，耗时9毫秒