用Java来获取访问者真实的IP地址

主要说明

在JSP里，获取客户端的IP地址的方法是：request.getRemoteAddr()，这种方法在大部分情况下都是有效的。但是在通过了Apache,Squid等反向代理软件就不能获取到客户端的真实IP地址了。如果使用了反向代理软件，用request.getRemoteAddr()方法获取的IP地址是：127.0.0.1或192.168.1.110，而并不是客户端的真实ＩＰ。

　　经过代理以后，由于在客户端和服务之间增加了中间层，因此服务器无法直接拿到客户端的 IP，服务器端应用也无法直接通过转发请求的地址返回给客户端。但是在转发请求的HTTP头信息中，增加了X－FORWARDED－FOR信息。用以跟踪原有的客户端IP地址和原来客户端请求的服务器地址。当我们访问index.jsp/时，其实并不是我们浏览器真正访问到了服务器上的index.jsp文件，而是先由代理服务器去访问index.jsp ，代理服务器再将访问到的结果返回给我们的浏览器，因为是代理服务器去访问index.jsp的，所以index.jsp中通过request.getRemoteAddr()的方法获取的IP实际上是代理服务器的地址，并不是客户端的IP地址。

（一）方法一　

　于是可得出获得客户端真实IP地址的方法一：

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

}  

（二）方法二

　　获得客户端真实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，如果通过了多级反向代理的话，X-Forwarded-For的值并不止一个，而是一串IP值，究竟哪个才是真正的用户端的真实IP呢？

　　答案是取X-Forwarded-For中第一个非unknown的有效IP字符串。如：
X-Forwarded-For：192.168.1.110, 192.168.1.120, 192.168.1.130, 192.168.1.100

用户真实IP为： 192.168.1.110

（三）方法三，参考网友代码

import javax.servlet.http.HttpServletRequest;  
  
/** 
 * 自定义访问对象工具类 
 *  
 * 获取对象的IP地址等信息 
 * @author X-rapido 
 * 
 */  
public class CusAccessObjectUtil {  
  
    /** 
     * 获取用户真实IP地址，不使用request.getRemoteAddr();的原因是有可能用户使用了代理软件方式避免真实IP地址, 
*  
     * 可是，如果通过了多级反向代理的话，X-Forwarded-For的值并不止一个，而是一串IP值，究竟哪个才是真正的用户端的真实IP呢？ 
     * 答案是取X-Forwarded-For中第一个非unknown的有效IP字符串。 
     *  
     * 如：X-Forwarded-For：192.168.1.110, 192.168.1.120, 192.168.1.130, 
     * 192.168.1.100 
     *  
     * 用户真实IP为： 192.168.1.110 
     *  
     * @param request 
     * @return 
     */  
    public static String getIpAddress(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.getHeader("HTTP_CLIENT_IP");  
        }  
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {  
            ip = request.getHeader("HTTP_X_FORWARDED_FOR");  
        }  
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {  
            ip = request.getRemoteAddr();  
        }  
        return ip;  
    }  
      
}

 /**

 *获取端口

 */

public void doGet(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
   String uri = request.getRequestURI();//返回请求行中的资源名称
   String url = request.getRequestURL().toString();//获得客户端发送请求的完整url
   String ip = request.getRemoteAddr();//返回发出请求的IP地址
   String params = request.getQueryString();//返回请求行中的参数部分
   String host=request.getRemoteHost();//返回发出请求的客户机的主机名
   int port =request.getRemotePort();//返回发出请求的客户机的端口号。
   System.out.println(ip);
   System.out.println(url);
   System.out.println(uri);
   System.out.println(params);
   System.out.println(host);
   System.out.println(port);
}

（四）网友总结的几种方法:

/**
     * 获取客户端ip地址(可以穿透代理)
     * 
     * @param request
     * @return
     */
    public static String getRemoteAddr(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.getHeader("HTTP_CLIENT_IP");
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getHeader("HTTP_X_FORWARDED_FOR");
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getRemoteAddr();
        }
        return ip;
    }
    private static final String[] HEADERS_TO_TRY = { 
        "X-Forwarded-For",
        "Proxy-Client-IP",
        "WL-Proxy-Client-IP",
        "HTTP_X_FORWARDED_FOR",
        "HTTP_X_FORWARDED",
        "HTTP_X_CLUSTER_CLIENT_IP",
        "HTTP_CLIENT_IP",
        "HTTP_FORWARDED_FOR",
        "HTTP_FORWARDED",
        "HTTP_VIA",
        "REMOTE_ADDR",
        "X-Real-IP"};

    /***
     * 获取客户端ip地址(可以穿透代理)
     * @param request
     * @return
     */
    public static String getClientIpAddress(HttpServletRequest request) {
        for (String header : HEADERS_TO_TRY) {
            String ip = request.getHeader(header);
            if (ip != null && ip.length() != 0 && !"unknown".equalsIgnoreCase(ip)) {
                return ip;
            }
        }
        return request.getRemoteAddr();
    }
    /***
     * 获取客户端ip地址(可以穿透代理)
     * @param request
     * @return
     */
    public static String getClientIpAddr(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.getHeader("HTTP_X_FORWARDED_FOR");  
        }  
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {  
            ip = request.getHeader("HTTP_X_FORWARDED");  
        }  
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {  
            ip = request.getHeader("HTTP_X_CLUSTER_CLIENT_IP");  
        }  
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {  
            ip = request.getHeader("HTTP_CLIENT_IP");  
        }  
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {  
            ip = request.getHeader("HTTP_FORWARDED_FOR");  
        }  
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {  
            ip = request.getHeader("HTTP_FORWARDED");  
        }  
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {  
            ip = request.getHeader("HTTP_VIA");  
        }  
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {  
            ip = request.getHeader("REMOTE_ADDR");  
        }  
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {  
            ip = request.getRemoteAddr();  
        }  
        return ip;  
    }
    public static String getIpAddr(HttpServletRequest request) {
        String ip = request.getHeader("X-Real-IP");
        if (null != ip && !"".equals(ip.trim())
                && !"unknown".equalsIgnoreCase(ip)) {
            return ip;
        }
        ip = request.getHeader("X-Forwarded-For");
        if (null != ip && !"".equals(ip.trim())
                && !"unknown".equalsIgnoreCase(ip)) {
            // get first ip from proxy ip
            int index = ip.indexOf(',');
            if (index != -1) {
                return ip.substring(0, index);
            } else {
                return ip;
            }
        }
        return request.getRemoteAddr();
    }

我使用的是spring MVC框架,测试的控制器代码如下:

package com.web.controller;

import java.util.HashMap;
import java.util.Map;

import javax.servlet.http.HttpServletRequest;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import com.common.util.SystemHWUtil;
import com.common.util.WebServletUtil;
import com.string.widget.util.ValueWidget;
import com.util.JSONPUtil;
/***
 * 用于测试跨域
 * @author huangweii
 * 2015年5月29日
 */
@Controller
@RequestMapping("/cors")
public class CORSController {
    @ResponseBody
    @RequestMapping(value = "/simple",produces=SystemHWUtil.RESPONSE_CONTENTTYPE_JSON_UTF)
    public String corsJsonSimple(HttpServletRequest request,String callback){
        String content;
        Map map=new HashMap();
        map.put("username", "黄威");
        map.put("age", "27");
        map.put("address", "beijing");
        content=HWJacksonUtils.getJsonP(map, callback);
        System.out.println("getIpAddr:"+WebServletUtil.getIpAddr(request));
        System.out.println("getRemoteAddr:"+WebServletUtil.getRemoteAddr(request));
        System.out.println("getClientIpAddr:"+WebServletUtil.getClientIpAddr(request));
        System.out.println("getClientIpAddress:"+WebServletUtil.getClientIpAddress(request));
        return content;
    }

}