Java 服务器获取请求的IP方法

class IpUtils {
     public static 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.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;
        }
}

PS：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

import javax.servlet.http.HttpServletRequest;
  
import org.apache.log4j.Logger;
  
  
public final class InternetProtocol {
    private static Logger log = Logger.getLogger(InternetProtocol.class);
    /**
     * 构造函数.
     */
    private InternetProtocol() {
    }
  
    /**
     * 获取客户端IP地址.<br>
     * 支持多级反向代理
     * 
     * @param request
     *            HttpServletRequest
     * @return 客户端真实IP地址
     */
    public static String getRemoteAddr(final HttpServletRequest request) {
        try{
            String remoteAddr = request.getHeader("X-Forwarded-For");
            // 如果通过多级反向代理，X-Forwarded-For的值不止一个，而是一串用逗号分隔的IP值，此时取X-Forwarded-For中第一个非unknown的有效IP字符串
            if (isEffective(remoteAddr) && (remoteAddr.indexOf(",") > -1)) {
                String[] array = remoteAddr.split(",");
                for (String element : array) {
                    if (isEffective(element)) {
                        remoteAddr = element;
                        break;
                    }
                }
            }
            if (!isEffective(remoteAddr)) {
                remoteAddr = request.getHeader("X-Real-IP");
            }
            if (!isEffective(remoteAddr)) {
                remoteAddr = request.getRemoteAddr();
            }
            return remoteAddr;
        }catch(Exception e){
            log.error("get romote ip error,error message:"+e.getMessage());
            return "";
        }
    }
      
    /**
     * 获取客户端源端口
     * @param request
     * @return
     */
    public static Long getRemotePort(final HttpServletRequest request){
        try{
            String port = request.getHeader("remote-port");
            if( StringUtil.isNotEmptyString(port )) {
                try{
                    return Long.parseLong(port);
                }catch(NumberFormatException ex){
                    log.error("convert port to long error,port: "+port);
                    return 0l;
                }
            }else{
                return 0l;
            }       
        }catch(Exception e){
            log.error("get romote port error,error message:"+e.getMessage());
            return 0l;
        }
    }
  
    /**
     * 远程地址是否有效.
     * 
     * @param remoteAddr
     *            远程地址
     * @return true代表远程地址有效，false代表远程地址无效
     */
    private static boolean isEffective(final String remoteAddr) {
        boolean isEffective = false;
        if ((null != remoteAddr) && (!"".equals(remoteAddr.trim()))
                && (!"unknown".equalsIgnoreCase(remoteAddr.trim()))) {
            isEffective = true;
        }
        return isEffective;
    }
}