now9999网站提示建设中,排行网页游戏,竞价托管外包,教育网站开发文档Redis限流接口防刷
Redis 除了做缓存#xff0c;还能干很多很多事情#xff1a;分布式锁、限流、处理请求接口幂等性。。。太多太多了#xff5e;
大家好#xff0c;我是llp#xff0c;许久没有写博客了#xff0c;今天就针对Redis实现接口限流做个记录。废话不多说还能干很多很多事情分布式锁、限流、处理请求接口幂等性。。。太多太多了
大家好我是llp许久没有写博客了今天就针对Redis实现接口限流做个记录。废话不多说我们先看下需求|应用场景
1.需求分析/图解
完成接口限流-防止某个用户频繁的请求秒杀接口比如在短时间内频繁点击抢购我们需要给用户访问频繁的提示, 示意图 2.简单接口限流
使用简单的 Redis 计数器, 完成接口限流防刷
除了计数器算法也有其它的算法来进行接口限流, 比如漏桶算法和令牌桶算法 (参考:https://zhuanlan.zhihu.com/p/165006444)令牌桶算法, 相对比较主流, 可以关注一下.
代码实现
RequestMapping(value /path, method RequestMethod.GET)
ResponseBody
public RespBean getPath(User user, Long goodsId, String captcha, HttpServletRequest request) {if (user null) {return RespBean.error(RespBeanEnum.SESSION_ERROR);}// 秒杀 v7.0 计数器 redis,5 秒内访问超过 5 次就认为是刷接口String uri request.getRequestURI();ValueOperations valueOperations redisTemplate.opsForValue();Integer count (Integer) valueOperations.get(uri : user.getId());if (count null) {//用户在5秒内没有访问过该接口keyuri : user.getId() value 1valueOperations.set(uri : user.getId(), 1, 5, TimeUnit.SECONDS);} else if (count 5) {//用户在5秒内访问过该接口但访问次数5则进行1valueOperations.increment(uri : user.getId());} else {//用户在5秒内访问次数5则对接口进行限流提示用户访问过于频繁return RespBean.error(RespBeanEnum.ACCESS_LIMIT_REACHED);}//验证用户输入的验证码boolean check orderService.checkCaptcha(user, goodsId, captcha);if (!check) {return RespBean.error(RespBeanEnum.CAPTCHA_ERROR);}//创建真正的地址String url orderService.createPath(user, goodsId);return RespBean.success(url);
}3.基于注解实现接口限流
自定义注解AccessLimit, 提高接口限流功能通用性 , 减少冗余代码, 同时也减少业 务代码入侵
思路分析-简单示意图
代码实现
自定义限流注解
/*** 限流注解*/
Retention(RetentionPolicy.RUNTIME)
Target(ElementType.METHOD)
public interface AccessLimit {//定义限制多少秒内进行限流int second();//定义多少秒内接口最大访问次数int maxCount();//接口是否需要验证登录信息boolean needLogin() default true;
}限流拦截器
Component
public class AccessLimitInterceptor implements HandlerInterceptor {Resourceprivate UserService userService;Resourceprivate RedisTemplate redisTemplate;/*** 1.preHandle 方法在目标方法执行前被执行* 2.如果返回fasle则不在执行目标方法** param request* param response* param handler* return* throws Exception*/Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {if (handler instanceof HandlerMethod) {User user getUser(request, response);UserContext.setUser(user);HandlerMethod handlerMethod (HandlerMethod) handler;AccessLimit accessLimit handlerMethod.getMethodAnnotation(AccessLimit.class);if (accessLimit null) {//没有直接放行return true;}boolean needLogin accessLimit.needLogin();int limitCount accessLimit.maxCount();int second accessLimit.second();if (needLogin user null) {render(response, RespBeanEnum.SESSION_ERROR);return false;}String uri request.getRequestURI();ValueOperations valueOperations redisTemplate.opsForValue();Integer count (Integer) valueOperations.get(uri : user.getId());if (count null) {//用户在5秒内没有访问过该接口keyuri : user.getId() value 1valueOperations.set(uri : user.getId(), 1, second, TimeUnit.SECONDS);} else if (count limitCount) {//用户在5秒内访问过该接口但访问次数5则进行1valueOperations.increment(uri : user.getId());} else {//用户在5秒内访问次数5则对接口进行限流提示用户访问过于频繁//返回错误信息render(response, RespBeanEnum.ACCESS_LIMIT_REACHED);return false;}}return true;}/*** 渲染错误信息返回** param response* param respBeanEnum*/private void render(HttpServletResponse response, RespBeanEnum respBeanEnum) throws IOException {System.out.println(render- respBeanEnum.getMessage());response.setContentType(application/json);response.setCharacterEncoding(utf-8);PrintWriter out response.getWriter();RespBean error RespBean.error(respBeanEnum);out.write(new ObjectMapper().writeValueAsString(error));out.flush();out.close();}//获取当前用户private User getUser(HttpServletRequest request, HttpServletResponse response) {String ticket CookieUtil.getCookieValue(request, userTicket);if (!StringUtils.hasText(ticket)) {return null;}return userService.getUserByTicket(request, response, ticket);}
}测试方法
RequestMapping(value /path, method RequestMethod.GET)
ResponseBody
/*** AccessLimit(second 5, maxCount 5, needLogin true)* 1. 使用注解的方式完成通用的接口防刷功能* 2. second 5, maxCount 5 5 秒内,最多 5 次请求,否性进行限流* 3. needLogin true 表示需要登录*/
AccessLimit(second 5, maxCount 5, needLogin true)
public RespBean getPath(User user, Long goodsId, String captcha, HttpServletRequest request) {if (user null) {return RespBean.error(RespBeanEnum.SESSION_ERROR);}// 秒杀 v7.0 计数器 redis,5 秒内访问超过 5 次就认为是刷接口String uri request.getRequestURI();ValueOperations valueOperations redisTemplate.opsForValue();Integer count (Integer) valueOperations.get(uri : user.getId());if (count null) {//用户在5秒内没有访问过该接口keyuri : user.getId() value 1valueOperations.set(uri : user.getId(), 1, 5, TimeUnit.SECONDS);} else if (count 5) {//用户在5秒内访问过该接口但访问次数5则进行1valueOperations.increment(uri : user.getId());} else {//用户在5秒内访问次数5则对接口进行限流提示用户访问过于频繁return RespBean.error(RespBeanEnum.ACCESS_LIMIT_REACHED);}//验证用户输入的验证码boolean check orderService.checkCaptcha(user, goodsId, captcha);if (!check) {return RespBean.error(RespBeanEnum.CAPTCHA_ERROR);}//创建真正的地址String url orderService.createPath(user, goodsId);return RespBean.success(url);
}//用来存储拦截器获取的 user 对象
public class UserContext {//每个线程都有自己的 threadlocal存在这里不容易混乱,线程安全private static ThreadLocalUser userHolder ThreadLocal.withInitial(() - null);public static void setUser(User user) {userHolder.set(user);}public static User getUser() {return userHolder.get();}}注册拦截器
EnableWebMvc
Configuration
public class WebConfig implements WebMvcConfigurer {Resourceprivate UserArgumentResolver userArgumentResolver;Resourceprivate AccessLimitInterceptor accessLimitInterceptor;/*** 注册拦截器*/Overridepublic void addInterceptors(InterceptorRegistry registry) {registry.addInterceptor(accessLimitInterceptor);}/*** 静态资源加载** param registry*/Overridepublic void addResourceHandlers(ResourceHandlerRegistry registry) {registry.addResourceHandler(/**).addResourceLocations(classpath:/static/);}/*** 将自定义参数解析器添加到解析器列表中** param resolvers*/Overridepublic void addArgumentResolvers(ListHandlerMethodArgumentResolver resolvers) {resolvers.add(userArgumentResolver);}}测试结果
