客户端的负载均衡器后面的IP地址

Question

我有以下课程来获取客户的IP地址

public class IpUtils {
     public static final String _255 = "(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)";
     public static final Pattern pattern = Pattern.compile("^(?:" + _255 + "\\.){3}" + _255 + "$");

     public static String longToIpV4(long longIp) {
        int octet3 = (int) ((longIp >> 24) % 256);
        int octet2 = (int) ((longIp >> 16) % 256);
        int octet1 = (int) ((longIp >> 8) % 256);
        int octet0 = (int) ((longIp) % 256);
        return octet3 + "." + octet2 + "." + octet1 + "." + octet0;
     }

     public static long ipV4ToLong(String ip) {
        String[] octets = ip.split("\\.");
        return (Long.parseLong(octets[0]) << 24) + (Integer.parseInt(octets[1]) << 16) +
            (Integer.parseInt(octets[2]) << 8) + Integer.parseInt(octets[3]);
 }

     public static boolean isIPv4Private(String ip) {
        long longIp = ipV4ToLong(ip);
        return (longIp >= ipV4ToLong("10.0.0.0") && longIp <= ipV4ToLong("10.255.255.255")) ||
            (longIp >= ipV4ToLong("172.16.0.0") && longIp <= ipV4ToLong("172.31.255.255")) ||
            longIp >= ipV4ToLong("192.168.0.0") && longIp <= ipV4ToLong("192.168.255.255");
     }

     public static boolean isIPv4Valid(String ip) {
        return pattern.matcher(ip).matches();
 }

     public static String getIpFromRequest(HttpServletRequest request) {
        String ip;
        boolean found = false;
        if ((ip = request.getHeader("x-forwarded-for")) != null) {
          StrTokenizer tokenizer = new StrTokenizer(ip, ",");
          while (tokenizer.hasNext()) {
            ip = tokenizer.nextToken().trim();
            if (isIPv4Valid(ip) && !isIPv4Private(ip)) {
              found = true;
              break;
            }
          }
        }
        if (!found) {
          ip = request.getRemoteAddr();
        }
        return ip;
      }
}

它首次给我正确的IP地址但是当会话建立时，此代码返回负载均衡器的IP地址。