SpringBoot如何对接口防刷限流处理

news2024/9/20 14:40:56

一、API防刷限流：

API接口限流，旨在预防用户过度频繁地访问特定接口，以及抵御潜在的恶意攻击行为，这些行为可能导致后端服务器承受过高的负载，进而引发内存资源紧张。为了有效缓解服务器面临的压力，确保服务的稳定性和可用性，对接口实施防刷限流措施显得尤为重要。

实现思路：

在Spring Boot应用中结合Redis实现后端拦截前端请求的功能，具体流程如下：后端系统拦截来自前端的每一个请求，使用请求的IP地址加上请求的具体信息（如接口路径、请求方法等）作为key，在Redis中查询对应的value值。若查询结果为空，表示这是该IP对该请求的首次访问，系统将继续执行后续操作，并在Redis中为该key设置一个初始的访问次数（如1）及过期时间。若查询结果不为空，则解析value值以获取当前的访问次数，并与预设的限定值进行比较。若访问次数超过限定值，则立即向前端返回提示信息，并终止执行后续操作；若未超过限定值，则更新Redis中的访问次数，并继续执行后续操作。

二、代码示例

第一步创建AccessLimitIntercept类，编写实现功能的核心代码。

package com.example.mybatisdemo.config;

import io.swagger.models.auth.In;
import org.apache.commons.lang3.ObjectUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.nio.charset.StandardCharsets;
import java.util.concurrent.TimeUnit;
import java.util.logging.Handler;

@Component

public class AccessLimitIntercept implements HandlerInterceptor {

  @Autowired
  private RedisTemplate redisTemplate;

  //限定访问次数
  private int count=5;
  //访问时间
  private int time=10;
 private final static String localIp = "127.0.0.1";
 /**
  * 获取ip地址
  * @param request
  * @return
  */
 public static String getIp(HttpServletRequest request){
     String ipAddress;
     try {
         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 (localIp.equals(ipAddress)) {
                 // 根据网卡取本机配置的IP
                 InetAddress inet = null;
                 try {
                     inet = InetAddress.getLocalHost();
                     ipAddress = inet.getHostAddress();
                 } catch (UnknownHostException e) {
                     e.printStackTrace();
                 }
             }
         }
         // 对于通过多个代理的情况，第一个IP为客户端真实IP,多个IP按照','分割
         if (ipAddress != null && ipAddress.length() > 15) {
             // = 15
             if (ipAddress.indexOf(",") > 0) {
                 ipAddress = ipAddress.substring(0, ipAddress.indexOf(","));
             }
         }
     } catch (Exception e) {
         ipAddress = "";
     }
     return "0:0:0:0:0:0:0:1".equals(ipAddress) ? localIp : ipAddress;
 }

 /**
  * 进入controller前的预处理
  * @param request
  * @param response
  * @param handler
  * @return
  * @throws Exception
  */
 @Override
 public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
     
     String key=getIp(request)+request.getRequestURI();
     Object value = redisTemplate.opsForValue().get(key);
     // 获取redis的value
     Integer valueTime=null;
     //表示第一次访问
     if(value==null)
     {
       //存放访问的次数，time表示时间， TimeUnit.SECONDS表示时间单位为秒
       redisTemplate.opsForValue().set(key, 1, time, TimeUnit.SECONDS);
     }
     if(value!=null)
     {
         valueTime= (Integer) value;

         if(valueTime<count)
         {
             //访问次数累加
             redisTemplate.opsForValue().set(key, valueTime+1, time, TimeUnit.SECONDS);

         }else {
             output(response, "{\"code\":\"8002\",\"message\":\"请求过于频繁，请稍后再试\"}");
             return false;
         }

     }
     return true;
 }
 public void output(HttpServletResponse response, String msg) throws IOException {
     response.setContentType("application/json;charset=UTF-8");
     ServletOutputStream outputStream = null;
     try {
         outputStream = response.getOutputStream();
         outputStream.write(msg.getBytes(StandardCharsets.UTF_8));
     } catch (IOException e) {
         e.printStackTrace();
     } finally {
         if (ObjectUtils.isNotEmpty(outputStream)) {
             outputStream.flush();
             outputStream.close();
         }
     }
 }

 @Override
 public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
     HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);
 }

 @Override
 public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
     HandlerInterceptor.super.afterCompletion(request, response, handler, ex);
 }
}

配置配置文件，将写好的拦截器配置到容器中

package com.example.mybatisdemo.config;

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

@Configuration
@EnableWebMvc
public class WebMvcConfig implements WebMvcConfigurer {

    /**
     * 这里需要先将限流拦截器入住，不然无法获取到拦截器中的redistemplate
     * @return
     */
    @Bean
    public AccessLimitIntercept getAccessLimitIntercept() {
        return new AccessLimitIntercept();
    }

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

创建 controller 测试类

@RestController
public class AcessController {


    @GetMapping("/test")

    public String Testmethod()
    {
        String st="hello,you enter system";
        System.out.println("成功访问到方法");
        return st;
    }

}

在浏览器访问 http://localhost:8080/test