获取客户端IP地址

/**
     * 获取客户端IP地址
     * */
    public String getRemortIP(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;   
    }

 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，那么真正的用户端的真实IP则是取X-Forwarded-For中第一个非unknown的有效IP字符串。