令牌桶限流

最新推荐文章于 2025-07-02 20:57:20 发布

2014Team

最新推荐文章于 2025-07-02 20:57:20 发布

阅读量1.7k

点赞数

CC 4.0 BY-SA版权

分类专栏： Spring Cloud

本文链接：https://blog.youkuaiyun.com/u012965203/article/details/99699448

Spring Cloud 专栏收录该内容

27 篇文章

订阅专栏

使用Guava库的RateLimit完成限流的，而其底层使用的是令牌桶算法实现的限流。

常用的限流算法有两种：漏桶算法和令牌桶算法

漏桶算法思路，水（请求）先进入到漏桶里，漏桶以一定的速度出水，当水流入速度过大会直接溢出，可以看出漏桶算法能强行限制数据的传输速率。

漏桶图1

对于很多应用场景来说，除了要求能够限制数据的平均传输速率外，还要求允许某种程度的突发传输。这时候漏桶算法可能就不合适了，令牌桶算法更为适合。如图2所示，令牌桶算法的原理是系统会以一个恒定的速度往桶里放入令牌，而如果请求需要被处理，则需要先从桶里获取一个令牌，当桶里没有令牌可取时，则拒绝服务。

令牌桶图2

二、基本环境搭建

一个eureka
一个网关zuul

三、创建eureka

（1）创建项目，命名00-eurekaserver-8000

（2）依赖

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
 
    <groupId>com.abc</groupId>
    <artifactId>00-eurekaserver-8000</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>
 
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.7.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
 
    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Greenwich.SR2</spring-cloud.version>
    </properties>
 
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>
 
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
 
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
 
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
 
</project>

（3）application.yml配置

server:
  port: 8000
 
eureka:
  instance:
    hostname: localhost  # 指定Eureka主机
  client:
    register-with-eureka: false   # 指定当前主机是否向Eureka服务器进行注册
    fetch-registry: false    # 指定当前主机是否要从Eurka服务器下载服务注册列表
    service-url:   # 服务暴露地址
     defaultZone: http://localhost:8000/eureka
#     defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka
 
#  server:
#    enable-self-preservation: false    # 关闭自我保护

（4）启动类

package com.abc.eureka;
 
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;
 
@SpringBootApplication
@EnableEurekaServer   // 开启Eureka服务
public class EurekaServerApplication {
 
    public static void main(String[] args) {
        SpringApplication.run(EurekaServerApplication.class, args);
    }
}

四、创建zuul

（1）创建项目，命名00-zuul-tokenbucket-9000

（2）依赖

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.abc</groupId>
    <artifactId>00-zuul-tokenbucket-9000</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.7.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Greenwich.SR1</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <!--zuul依赖-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-zuul</artifactId>
        </dependency>
    </dependencies>


    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

（3）application.yml配置

server:
  port: 9000

eureka:
  client:
    service-url:
      defaultZone: http://localhost:8000/eureka

spring:
  application:
    name: abcmsc-zuul-depart

zuul:
  routes:
    # 指定微服务的路由规则
    abcmsc-consumer-depart-8080: /abc8080/**
    abcmsc-consumer-depart-8090: /abc8090/**
    abcmsc-consumer-depart: /abc012/**

（4）ZuulFilter类

package com.abc.zuul.filter;

import com.google.common.util.concurrent.RateLimiter;
import com.netflix.zuul.ZuulFilter;
import com.netflix.zuul.context.RequestContext;
import com.netflix.zuul.exception.ZuulException;
import lombok.extern.slf4j.Slf4j;
import org.springframework.cloud.netflix.zuul.filters.support.FilterConstants;
import org.springframework.stereotype.Component;

@Component
@Slf4j
public class RouteFilter extends ZuulFilter {

    // 定义一个令牌桶，每秒产生2个令牌，即每秒最多处理2个请求
    private static final RateLimiter RATE_LIMITER = RateLimiter.create(2);

    @Override
    public String filterType() {
        return FilterConstants.PRE_TYPE;
    }

    @Override
    public int filterOrder() {
        return -5;
    }

    @Override
    public Object run() throws ZuulException {
        log.info("通过过滤");
        return null;
    }

    @Override
    public boolean shouldFilter() {
        // 获取请求上下文
        RequestContext context = RequestContext.getCurrentContext();

        // tryAcquire() 只要能够马上获致到1个令牌，则返回true，不阻塞
        // tryAcquire(5, 3, TimeUnit.SECONDS) 在3秒钟内可以获取到5个令牌，则返回true，不阻塞
        // acquire(5) 获取到5个令牌，否则一直等待，会阻塞，返回值为阻塞的时长
        // acquire() 获取到1个令牌，否则一直等待，会阻塞，返回值为阻塞的时长
        if(!RATE_LIMITER.tryAcquire()) {
            log.warn("访问量超载");
            // 指定当前请求未通过过滤
            context.setSendZuulResponse(false);
            // 向客户端返回响应码429，请求数量过多
            context.setResponseStatusCode(429);
            return false;
        }
        return true;
    }
}

（5）启动类

package com.abc.zuul;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.zuul.EnableZuulProxy;

@EnableZuulProxy    // 开启zuul代理模式
@SpringBootApplication
public class ZuulApplication {

    public static void main(String[] args) {
        SpringApplication.run(ZuulApplication.class, args);
    }

}

五、测试

（1）启动eureka