NetworkUtils

import java.io.IOException;

import javax.servlet.http.HttpServletRequest;

import org.apache.log4j.Logger;

public class NetworkUtils {

     private static Logger logger = Logger.getLogger(NetworkUtils.class); 

    /**
     * 获取请求主机IP地址,如果通过代理进来，则透过防火墙获取真实IP地址;
     *
     * @param request
     * @return
     * @throws IOException
     */
    public final static String getIpAddress(HttpServletRequest request) throws IOException {  

        // 获取请求主机IP地址,如果通过代理进来，则透过防火墙获取真实IP地址
        String ip = request.getHeader("X-Forwarded-For");
        if (logger.isDebugEnabled()) {
            logger.debug("getIpAddress(HttpServletRequest) - X-Forwarded-For - String ip=" + ip);
        }  

        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
                ip = request.getHeader("Proxy-Client-IP");
                if (logger.isDebugEnabled()) {
                    logger.debug("getIpAddress(HttpServletRequest) - Proxy-Client-IP - String ip=" + ip);
                }
            }
            if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
                ip = request.getHeader("WL-Proxy-Client-IP");
                if (logger.isDebugEnabled()) {
                    logger.debug("getIpAddress(HttpServletRequest) - WL-Proxy-Client-IP - String ip=" + ip);
                }
            }
            if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
                ip = request.getHeader("HTTP_CLIENT_IP");
                if (logger.isDebugEnabled()) {
                    logger.debug("getIpAddress(HttpServletRequest) - HTTP_CLIENT_IP - String ip=" + ip);
                }
            }
            if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
                ip = request.getHeader("HTTP_X_FORWARDED_FOR");
                if (logger.isDebugEnabled()) {
                    logger.debug("getIpAddress(HttpServletRequest) - HTTP_X_FORWARDED_FOR - String ip=" + ip);
                }
            }
            if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
                ip = request.getRemoteAddr();
                if (logger.isDebugEnabled()) {
                    logger.debug("getIpAddress(HttpServletRequest) - getRemoteAddr - String ip=" + ip);
                }
            }
        } else if (ip.length() > 15) {  // 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
            String[] ips = ip.split(",");
            for (int index = 0; index < ips.length; index++) {
                String strIp = (String) ips[index];
                if (!("unknown".equalsIgnoreCase(strIp))) {
                    ip = strIp;
                    break;
                }
            }
        }
        return ip;
    }
}