在jsp里怎么取IP地址？？

我写了个投票系统，目的想限制一个ip地址只能头一次、
我在网上贴了两个方法，写成了一个类
package A;
import javax.servlet.http.HttpServletRequest;
public class a {
public String getRemortIP(HttpServletRequest request)
{   
if (request.getHeader("x-forwarded-for") == null)
{   
return request.getRemoteAddr();       
}     
return request.getHeader("x-forwarded-for");     
    } 
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;
} 
}
接着有些了个jsp来调用：
<%@ page language="java" import="java.util.*,A.*" pageEncoding="utf-8"%>
<jsp:use