Nginx reverse proxy to obtain the real IP address of the device

package com.das.common.util;

import org.apache.commons.lang3.StringUtils;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import javax.servlet.http.HttpServletRequest;

/**
 * @Author lime
 * @Date 2018/1/31
 */ 
public  class IpUtil {

    public static String getIpAddress(HttpServletRequest request) {
        String xIp = request.getHeader("X-Real-IP");
        String xFor = request.getHeader("X-Forwarded-For" );
         if (StringUtils.isNotEmpty(xFor) && !"unKnown" .equalsIgnoreCase(xFor)){
             // There will be multiple ip values ​​after multiple reverse proxies , the first ip is the real ip 
            int index = xFor.indexOf("," );
             if (index != -1 ){
                 return xFor.substring(0 ,index);
            }else{
                return xFor;
            }
        }
        xFor = xIp;
        if(StringUtils.isNotEmpty(xFor) && !"unKnown".equalsIgnoreCase(xFor)){
            return xFor;
        }
        if (StringUtils.isBlank(xFor) || "unknown".equalsIgnoreCase(xFor)) {
            xFor = request.getHeader("Proxy-Client-IP");
        }
        if (StringUtils.isBlank(xFor) || "unknown".equalsIgnoreCase(xFor)) {
            xFor = request.getHeader("WL-Proxy-Client-IP");
        }
        if (StringUtils.isBlank(xFor) || "unknown".equalsIgnoreCase(xFor)) {
            xFor = request.getHeader("HTTP_CLIENT_IP");
        }
        if (StringUtils.isBlank(xFor) || "unknown".equalsIgnoreCase(xFor)) {
            xFor = request.getHeader("HTTP_X_FORWARDED_FOR");
        }
        if (StringUtils.isBlank(xFor) || "unknown".equalsIgnoreCase(xFor)) {
            xFor = request.getRemoteAddr();
        }
        return xFor;
    }

    public static String getIpAddress() {
        HttpServletRequest request = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest();
        return getIpAddress(request);
    }
}

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