方法一：

if('/'==DIRECTORY_SEPARATOR){

    $server_ip=$_SERVER['SERVER_ADDR'];

}else{

    $server_ip=@gethostbyname($_SERVER['SERVER_NAME']);

}

echo $server_ip;

方法二：

/**

* 获取服务器端IP地址

 * @return string

*/

function get_server_ip(){

    if(isset($_SERVER)){

        if($_SERVER['SERVER_ADDR']){

            $server_ip=$_SERVER['SERVER_ADDR'];

        }else{

            $server_ip=$_SERVER['LOCAL_ADDR'];

        }

    }else{

        $server_ip = getenv('SERVER_ADDR');

    }

    return $server_ip;

}

echo get_server_ip();