限流实战：guava的RateLimiter实现令牌桶算法限流

1 引入依赖

2 限流实现

3 自定义拦截器，在拦截器中实现限流

4 实现 WebMvcConfigurer 添加自定义拦截器

5 RateLimiterAnnotation 实现

6 Controller 类实现

7 通过 jmeter 进行限流测试

限流和限流算法已经介绍了常见的限流算法。guava 的 RateLimiter 使用的是令牌桶算法。

本次实战，我们用的是 guava 的 RateLimiter，springboot 在处理请求时候，从桶中申请令牌，申请到了就成功响应，申请不到时直接返回失败。

1 引入依赖

<dependency>
    <groupId>com.google.guava</groupId>
    <artifactId>guava</artifactId>
    <version>18.0</version>
</dependency>

2 限流实现

package com.sb.rateLimiter.service;

import com.google.common.util.concurrent.RateLimiter;
import org.springframework.stereotype.Service;

@Service
public class RateLimiterService {
    /**
     * 每秒只发出5个令牌
     */
    RateLimiter rateLimiter = RateLimiter.create(5.0);

    /**
     * 尝试获取令牌
     * @return
     */
    public boolean tryAcquire(){
        return rateLimiter.tryAcquire();
    }
}

3 自定义拦截器，在拦截器中实现限流

package com.sb.rateLimiter.interceptor;
import com.sb.rateLimiter.annotation.RateLimiterAnnotation;
import com.sb.rateLimiter.service.RateLimiterService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.annotation.Resource;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@Component
public class RateLimiterInterceptor implements HandlerInterceptor {
    @Resource
    private RateLimiterService accessLimitService;

    private Logger logger = LoggerFactory.getLogger(RateLimiterInterceptor.class);

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        if (!(handler instanceof HandlerMethod)) {
            return true;
        }

        HandlerMethod handlerMethod = (HandlerMethod) handler;
        RateLimiterAnnotation rateLimiterAnnotation = handlerMethod.getMethod().getAnnotation(RateLimiterAnnotation.class);
        if(rateLimiterAnnotation == null) {
            return true;
        }

        if (!accessLimitService.tryAcquire()) {
            logger.info("限流中......");
            return false;
        }
        logger.info("请求成功");
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

    }
}

4 实现 WebMvcConfigurer 添加自定义拦截器

package com.sb.rateLimiter.config;
import com.sb.rateLimiter.interceptor.RateLimiterInterceptor;
import org.springframework.boot.SpringBootConfiguration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import javax.annotation.Resource;

@SpringBootConfiguration
public class WebConfiguration implements WebMvcConfigurer {

    @Resource
    private RateLimiterInterceptor rateLimiterInterceptor;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(rateLimiterInterceptor).addPathPatterns("/**");
    }
}

5 RateLimiterAnnotation 实现

package com.sb.rateLimiter.annotation;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface RateLimiterAnnotation {
    int rateLimiterNumber() default 1;
}

6 Controller 类实现

package com.sb.rateLimiter.controller;
import com.sb.rateLimiter.annotation.RateLimiterAnnotation;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/api")
public class RateLimiterController {

    @RateLimiterAnnotation
    @RequestMapping(value = "/rateLimiterTest", method = RequestMethod.GET)
    public void rateLimiterTest() throws Exception {
        //业务逻辑;
    }
}