SpringMVC 限流的示例代码

<!-- https://mvnrepository.com/artifact/com.google.guava/guava -->
<dependency>
  <groupId>com.google.guava</groupId>
  <artifactId>guava</artifactId>
  <version>21.0</version>
</dependency>

// https://mvnrepository.com/artifact/com.google.guava/guava
compile 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;
  }
}

@Component
public 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);
  }

}