获取访问者的IP

import java.io.Serializable;
import java.net.InetAddress;
import java.net.UnknownHostException;

import javax.servlet.http.HttpServletRequest;

public class IpUtil implements Serializable {
    private static final long serialVersionUID = -2714197398219631534L;

    public static String getIpAddrByRequest(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;

    }

    public static String getIpAddr(HttpServletRequest request) {
        String ipAddress = null;
        ipAddress = request.getHeader("x-forwarded-for");
        if (ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)) {
            ipAddress = request.getHeader("Proxy-Client-IP");
        }
        if (ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)) {
            ipAddress = request.getHeader("WL-Proxy-Client-IP");
        }
        if (ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)) {
            ipAddress = request.getRemoteAddr();

            // 这里主要是获取本机的ip,可有可无
            if (ipAddress.equals("127.0.0.1")
                    || ipAddress.endsWith("0:0:0:0:0:0:1")) {
                // 根据网卡取本机配置的IP
                InetAddress inet = null;
                try {
                    inet = InetAddress.getLocalHost();
                } catch (UnknownHostException e) {
                    e.printStackTrace();
                }
                ipAddress = inet.getHostAddress();
            }

        }

        // 对于通过多个代理的情况，第一个IP为客户端真实IP,多个IP按照','分割
        if (ipAddress != null && ipAddress.length() > 15) { // "***.***.***.***".length()
                                                            // = 15
            if (ipAddress.indexOf(",") > 0) {
                ipAddress = ipAddress.substring(0, ipAddress.indexOf(","));
            }
        }
        return ipAddress;
    }
}