用户Ip地址，先取x_forwarded_for值，不为空则为用户IP，如果为空再取remote_ip的值

public 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.getRemoteAddr();
        }
        if (!(null == ip || "".equals(ip.trim()) || "null".equalsIgnoreCase(ip.trim())) && ip.contains(",")) {
            ip = ip.split(",")[0];
        }
        return ip;
    }