public String getRemortIP(HttpServletRequest request) { if (request.getHeader("x-forwarded-for") == null) { return request.getRemoteAddr(); } return request.getHeader("x-forwarded-for"); }

可是當我訪問http://www.xxx.com/index.jsp/ 時，返回的IP地址始終是unknown，也並不是如上所示的127.0.0.1　或　192.168.1.110了，而我訪問http://192.168.1.110:2046/index.jsp

於是可得出獲得客戶端真實IP地址的方法二：

public String getIpAddr(HttpServletRequest request) {
       String ip = request.getHeader("x-forwarded-for");
       if(ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
           ip = request.getHeader("Proxy-Client-IP");
       }
       if(ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
           ip = request.getHeader("WL-Proxy-Client-IP");
       }
       if(ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
           ip = request.getRemoteAddr();
       }
       return ip;
   }
 

 可是，如果通過了多級反向代理的話，X-Forwarded-For的值並不止一個，而是一串Ｉｐ值，究竟哪個才是真正的使用者端的真實IP呢？

　　答案是取X-Forwarded-For中第一個非unknown的有效IP字串。

　　如：
　　X-Forwarded-For：192.168.1.110, 192.168.1.120, 192.168.1.130, 192.168.1.100
　　使用者真實IP為： 192.168.1.110