java如何根据HttpServletRequest获取IP地址

public static String getIPAddress(HttpServletRequest request) {
    String ip = null;    //X-Forwarded-For：Squid 服务代理
    String ipAddresses = request.getHeader("X-Forwarded-For");
    if (ipAddresses == null || ipAddresses.length() == 0 || "unknown".equalsIgnoreCase(ipAddresses)) {        //Proxy-Client-IP：apache 服务代理
        ipAddresses = request.getHeader("Proxy-Client-IP");
    }
    if (ipAddresses == null || ipAddresses.length() == 0 || "unknown".equalsIgnoreCase(ipAddresses)) {        //WL-Proxy-Client-IP：weblogic 服务代理
        ipAddresses = request.getHeader("WL-Proxy-Client-IP");
    }
    if (ipAddresses == null || ipAddresses.length() == 0 || "unknown".equalsIgnoreCase(ipAddresses)) {        //HTTP_CLIENT_IP：有些代理服务器
        ipAddresses = request.getHeader("HTTP_CLIENT_IP");
    }
    if (ipAddresses == null || ipAddresses.length() == 0 || "unknown".equalsIgnoreCase(ipAddresses)) {        //X-Real-IP：nginx服务代理
        ipAddresses = request.getHeader("X-Real-IP");
    }    //有些网络通过多层代理，那么获取到的ip就会有多个，一般都是通过逗号（,）分割开来，并且第一个ip为客户端的真实IP
    if (ipAddresses != null && ipAddresses.length() != 0) {
        ip = ipAddresses.split(",")[0];
    }    //还是不能获取到，最后再通过request.getRemoteAddr();获取
    if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ipAddresses)) {
        ip = request.getRemoteAddr();
    }
    return ip;
}

public static String getIpAddr(HttpServletRequest request)
    {
        if (request == null)
        {
            return "unknown";
        }
        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("X-Forwarded-For");
        }
        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("X-Real-IP");
        }

        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip))
        {
            ip = request.getRemoteAddr();
        }
        return "0:0:0:0:0:0:0:1".equals(ip) ? "127.0.0.1" : EscapeUtil.clean(ip);
    }