SpringMVC 限流的示例代码

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// https://mvnrepository.com/artifact/com.google.guava/guavacompile group: 'com.google.guava', name: 'guava', version: '21.0'

import com.google.common.util.concurrent.RateLimiter;import org.springframework.web.servlet.ModelAndView;import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.util.concurrent.TimeUnit;public class SmoothBurstyInterceptor extends HandlerInterceptorAdapter {  public enum LimitType {    DROP,//丢弃    WAIT //等待  }  /**   * 限流器   */  private RateLimiter limiter;  /**   * 限流方式   */  private LimitType limitType = LimitType.DROP;  public SmoothBurstyInterceptor() {    this.limiter = RateLimiter.create(10);  }  /**   * @param tps    限流量 (每秒处理量)   * @param limitType 限流类型:等待/丢弃(达到限流量)   */  public SmoothBurstyInterceptor(int tps, SmoothBurstyInterceptor.LimitType limitType) {    this.limiter = RateLimiter.create(tps);    this.limitType = limitType;  }  /**   * @param permitsPerSecond 每秒新增的令牌数   * @param limitType 限流类型:等待/丢弃(达到限流量)   */  public SmoothBurstyInterceptor(double permitsPerSecond, SmoothBurstyInterceptor.LimitType limitType) {    this.limiter = RateLimiter.create(permitsPerSecond, 1000, TimeUnit.MILLISECONDS);    this.limitType = limitType;  }  @Override  public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {    if (limitType.equals(LimitType.DROP)) {      if (limiter.tryAcquire()) {        return super.preHandle(request, response, handler);      }    } else {      limiter.acquire();      return super.preHandle(request, response, handler);    }    throw new Exception("网络异常!");//达到限流后，往页面提示的错误信息。  }  @Override  public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {    super.postHandle(request, response, handler, modelAndView);  }  @Override  public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {    super.afterCompletion(request, response, handler, ex);  }  public RateLimiter getLimiter() {    return limiter;  }  public void setLimiter(RateLimiter limiter) {    this.limiter = limiter;  }}

@Componentpublic class WebConfig extends WebMvcConfigurerAdapter {  @Override  public void addInterceptors(InterceptorRegistry registry) {    // 多个拦截器组成一个拦截器链    registry.addInterceptor(new SmoothBurstyInterceptor(100, SmoothBurstyInterceptor.LimitType.DROP)).addPathPatterns("/**");    //限流可配置为SmoothBurstyInterceptor.LimitType.DROP丢弃请求或者SmoothBurstyInterceptor.LimitType.WAIT等待，100为每秒的速率    super.addInterceptors(registry);  }}