在java中获取客户端真实的IP地址

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