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Editor to share with you how to achieve Java interface current limit, I hope you will learn something after reading this article, let's discuss it together!

RateLimiter

Google open source toolkit Guava provides a current-limiting tool class RateLimiter, which is implemented based on token bucket algorithm.

1.maven dependence: com.google.guava guava 27.1-jre2. Custom annotation import java.lang.annotation.*;import java.util.concurrent.TimeUnit;/** * token bucket annotation implementation * / @ Target ({ElementType.METHOD}) @ Retention (RetentionPolicy.RUNTIME) @ Documentedpublic @ interface RequestLimiter {/ * create tokens per second. Default: 10 * / double QPS () token 10D / * * get token wait timeout default: 500 * / long timeout () default 500; / * timeout unit default: millisecond * / TimeUnit timeunit () default TimeUnit.MILLISECONDS; / * unable to get token return message * / String msg () default "Please try again later!";} 3. Interceptor import com.alibaba.fastjson.JSON;import com.alibaba.fastjson.JSONObject;import com.google.common.util.concurrent.RateLimiter;import com.tiam.panshi.cloud.appback.annotation.RequestLimiter;import lombok.extern.slf4j.Slf4j;import org.springframework.stereotype.Component;import org.springframework.web.method.HandlerMethod;import org.springframework.web.servlet.HandlerInterceptor;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.PrintWriter;import java.util.Map;import java.util.concurrent.ConcurrentHashMap @ Component@Slf4jpublic class RequestLimitingInterceptor implements HandlerInterceptor {private final Map rateLimiterMap = new ConcurrentHashMap (); @ Override public boolean preHandle (HttpServletRequest request, HttpServletResponse response, Object handler) {/ / you can pull out and define the return information JSONObject jsonObject = new JSONObject (); jsonObject.put ("10001", "loading with life, please try again later") Try {if (handler instanceof HandlerMethod) {HandlerMethod handlerMethod = (HandlerMethod) handler; RequestLimiter rateLimit = handlerMethod.getMethodAnnotation (RequestLimiter.class); / / determine whether there is an annotation if (rateLimit! = null) {/ / get request url String url = request.getRequestURI () RateLimiter rateLimiter; / / determine whether there is a created token bucket in the map collection if (! rateLimiterMap.containsKey (url)) {/ / create a token bucket, and put the token rateLimiter = RateLimiter.create (rateLimit.QPS ()) in the bucket with n r _ packs. RateLimiterMap.put (url, rateLimiter);} rateLimiter = rateLimiterMap.get (url); / / get token boolean acquire = rateLimiter.tryAcquire (rateLimit.timeout (), rateLimit.timeunit ()) If (acquire) {/ / token obtained successfully return true;} else {log.warn ("request is restricted, url: {}", request.getServletPath ()); makeResult (response, renderJson (jsonObject)) Return false;} return true;} catch (Exception var6) {var6.printStackTrace (); makeResult (response, renderJson (jsonObject)); return false } private void makeResult (HttpServletResponse response, JSONObject jo) {response.setContentType ("application/json; charset=utf-8"); response.setCharacterEncoding ("UTF-8"); try (PrintWriter out = response.getWriter ()) {out.append (jo.toJSONString ());} catch (Exception e) {e.printStackTrace () } private JSONObject renderJson (Object o) {return JSONObject.parseObject (JSON.toJSONString (o));} 4. Register interceptor @ Configurationpublic class WebMvcConfig extends WebMvcConfigurationSupport {/ * request current limit interceptor * / @ Autowired protected RequestLimitingInterceptor requestLimitingInterceptor; @ Override public void addInterceptors (InterceptorRegistry registry) {/ / request current limit registry.addInterceptor (requestLimitingInterceptor) .addPathPatterns ("/ * *");}} 5. Configure @ RequestLimiter on the interface (QPS = 5D, timeout = 200, timeunit = TimeUnit.MILLISECONDS,msg = "loading with life, please try again later") @ GetMapping ("/ test") @ ResponseBodypublic String test () {return ";} after reading this article, I believe you have some understanding of" how Java implements interface current limiting ". If you want to know more about it, welcome to follow the industry information channel. Thank you for reading!

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