获取IP

 /***
 * 获取IP（如果是多级代理，则得到的是一串IP值）
 */
public static 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();
   }
   if (ip != null && ip.length() > 0) {
      String[] ips = ip.split(",");
      for (int i = 0; i < ips.length; i++) {
         if (!"unknown".equalsIgnoreCase(ips[i])) {
            ip = ips[i];
            break;
         }
      }
   }
   return ip;
}