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; }}