目录
4 实现 WebMvcConfigurer 添加自定义拦截器
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.Enum.ResponseEnum;
import com.sb.rateLimiter.annotation.RateLimiterAnnotation;
import com.sb.rateLimiter.dto.RetDTO;
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 RetDTO rateLimiterTest() throws Exception {
return RetDTO.getReturnJson(ResponseEnum.OK);
}
}
7 通过 jmeter 进行限流测试
