springboot+redis 實(shí)現分布式限流令牌桶的示例代碼

1、前言

網(wǎng)上找了很多redis分布式限流方案，要不就是太大，需要引入第三方j(luò )ar，而且還無(wú)法正常運行，要不就是定時(shí)任務(wù)定時(shí)往key中放入數據，使用的時(shí)候調用，嚴重影響性能，所以著(zhù)手自定義實(shí)現redis令牌桶。
只用到了spring-boot-starter-data-redis包，并且就幾行代碼。

2、環(huán)境準備

a、idea新建springboot項目，引入spring-data-redis包
b、編寫(xiě)令牌桶實(shí)現方法RedisLimitExcutor
c、測試功能，創(chuàng )建全局攔截器，測試功能

3、上代碼

maven添加依賴(lài)

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>

令牌桶實(shí)現方法RedisLimitExcutor

package com.example.redis_limit_demo.config;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.data.redis.core.script.RedisScript;
import org.springframework.stereotype.Component;

import java.util.ArrayList;
import java.util.List;

/**
 * 令牌桶實(shí)現
 */
@Component
public class RedisLimitExcutor {

    private StringRedisTemplate stringRedisTemplate;

    @Autowired
    public void setStringRedisTemplate(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    /**
     * 令牌的
     *
     * @param key        key值
     * @param limitCount 容量
     * @param seconds    時(shí)間間隔
     * @return
     */
    public boolean tryAccess(String key, int limitCount, int seconds) {
        String luaScript = buildLuaScript();
        RedisScript<Long> redisScript = new DefaultRedisScript<>(luaScript, Long.class);
        List<String> keys = new ArrayList<>();
        keys.add(key);
        Long count = stringRedisTemplate.execute(redisScript, keys, String.valueOf(limitCount), String.valueOf(seconds));
        if (count != 0) {
            return true;
        } else {
            return false;
        }
    }

    /**
     * 腳本
     *
     * @return
     */
    private static final String buildLuaScript() {
        StringBuilder lua = new StringBuilder();
        lua.append(" local key = KEYS[1]");
        lua.append("\nlocal limit = tonumber(ARGV[1])");
        lua.append("\nlocal curentLimit = tonumber(redis.call('get', key) or \"0\")");
        lua.append("\nif curentLimit + 1 > limit then");
        lua.append("\nreturn 0");
        lua.append("\nelse");
        lua.append("\n redis.call(\"INCRBY\", key, 1)");
        lua.append("\nredis.call(\"EXPIRE\", key, ARGV[2])");
        lua.append("\nreturn curentLimit + 1");
        lua.append("\nend");
        return lua.toString();
    }
}

攔截器配置WebAppConfig

package com.example.redis_limit_demo.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

/**
 * 攔截器配置
 */
@Configuration
public class WebAppConfig implements WebMvcConfigurer {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(getRequestInterceptor()).addPathPatterns("/**");
    }

    @Bean
    public RequestInterceptor getRequestInterceptor() {
        return new RequestInterceptor();
    }
}

攔截器實(shí)現RequestInterceptor

package com.example.redis_limit_demo.config;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.HandlerInterceptor;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.net.InetAddress;
import java.net.UnknownHostException;

/**
 * 攔截器實(shí)現
 */
@Configuration
public class RequestInterceptor implements HandlerInterceptor {
    @Autowired
    private RedisLimitExcutor redisLimitExcutor;


    /**
     * 只有返回true才會(huì )繼續向下執行，返回false取消當前請求
     *
     * @param request
     * @param response
     * @param handler
     * @return
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) {
        /**
         * 根據實(shí)際情況設置QPS
         */
        String url = request.getRequestURI();
        String ip = getIpAdd(request);
        //QPS設置為5，手動(dòng)刷新接口可以測試出來(lái)
        if (!redisLimitExcutor.tryAccess(ip+url, 5, 1)) {
            throw new RuntimeException("調用頻繁");
        } else {
            return true;
        }
    }

    public static final  String getIpAdd(HttpServletRequest request) {
        String ipAddress = request.getHeader("x-forwarded-for");
        if (ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)) {
            ipAddress = request.getHeader("Proxy-Client-IP");
        }
        if (ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)) {
            ipAddress = request.getHeader("WL-Proxy-Client-IP");
        }
        if (ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)) {
            ipAddress = request.getRemoteAddr();
            if (ipAddress.equals("127.0.0.1") || ipAddress.equals("0:0:0:0:0:0:0:1")) {
                // 根據網(wǎng)卡取本機配置的IP
                InetAddress inet = null;
                try {
                    inet = InetAddress.getLocalHost();
                } catch (UnknownHostException e) {
                    return null;
                }
                ipAddress = inet.getHostAddress();
            }
        }
        // 如果通過(guò)代理訪(fǎng)問(wèn),可能獲取2個(gè)IP,這時(shí)候去第二個(gè)(代理服務(wù)端IP)
        if (ipAddress.split(",").length > 1) {
            ipAddress = ipAddress.split(",")[1].trim();
        }
        return ipAddress;
    }


}

測試controller

package com.example.redis_limit_demo.controller;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RequestMapping("demo")
@RestController
public class DemoController {


    @RequestMapping("limit")
    public String demo() {
        //todo 寫(xiě)業(yè)務(wù)邏輯
        return "aaaaa";
    }

}

4、運行項目，訪(fǎng)問(wèn)接口

http://localhost:8080/demo/limit

當刷新頻率高了以后，就會(huì )報錯

5、（GitHub經(jīng)常訪(fǎng)問(wèn)不到）

備注：

1、 redis的key可以根據實(shí)際情況設置，入例子中的ip+url，可以將全部流量進(jìn)行控制，防止惡意刷接口，但需要注意的是，使用ip方式，要將QPS設置大一些，因為會(huì )出現整個(gè)大廈公用一個(gè)ip的情況。也可以使用url+userName，將QPS設置小一點(diǎn)，可以更加精準的限制api的訪(fǎng)問(wèn)。
2、可以將拋出異常進(jìn)行全局捕獲和統一返回。

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