服务器使用nginx做代理，通过HttpServletRequest获取请求用户真实IP地址

server {
    listen       80;
    server_name  www.wenki.info;    #要访问的域名

    charset utf8;

    location / {
        proxy_pass       http://wenki_info;
        proxy_set_header Host      $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }
}

nginx -s reload

public static String realIP(HttpServletRequest request) {
    String xff = request.getHeader("x-forwarded-for");
    if (xff != null) {
        int index = xff.indexOf(‘,‘);
        if (index != -1) {
            xff = xff.substring(0, index);
        }
        return xff.trim();
    }
    return request.getRemoteAddr();
}