PHP登录表单不起作用

Question

我有一个我正在尝试的网站登录表单应该登录用户，但登录表单随机停止工作。当用户提交登录表单时，它会将所有内容传递给class.login.php并验证登录。 class.login.php：

<?php
error_reporting(0);
require('/inc.all.php');
class Login
{
    private $_id;
    private $_username;
    private $_password;
    private $_passmd5;

    private $_errors;
    private $_access;
    private $_login;
    private $_token;

    public function __construct()
    {
        $this->_errors = array();
        $this->_login = isset($_POST['login']) ? 1 : 0;
        $this->_access = 0;
        $this->_token = $_POST['token'];

        $this->_id = 0;
        $this->_username = ($this->_login) ? $this->filter($_POST['username']) :
            $_SESSION['username'];
        $this->_password = ($this->_login) ? $this->filter($_POST['password']) :
            '';
        $this->_passmd5 = ($this->_login) ? md5($this->_password) :
            $_SESSION['password'];
    }

    public function isLoggedIn()
    {
        ($this->_login) ? $this->verifyPost() : $this->verifySession();

        return $this->_access;
    }

    public function filter($var)
    {
        return preg_replace('/[^a-zA-Z0-9]/', '', $var);
    }

    public function verifyPost()
    {
        try {
            if (!$this->isTokenValid())
                throw new Exception('Invalid Form Submission');

            if (!$this->isDataValid())
                throw new Exception('Invalid Form Data');

            if (!$this->verifyDatabase())
                throw new Exception('Invalid Username/Password');

            $this->_access = 1;
            $this->registerSession();
        } catch (Exception $e) {
            $this->_errors[] = $e->getMessage();
        }
    }

    public function verifySession()
    {
        if ($this->sessionExist() && $this->verifyDatabase())
            $this->_access = 1;
    }

    public function verifyDatabase()
    {
        mysql_select_db("minecraftprofiles");
        $data = mysql_query("
            SELECT ID
            FROM user_login
            WHERE
                username = '{$this->_username}'
                AND password = '{$this->_passmd5}'
        ");
        if (mysql_num_rows($data)) {
            list($this->_id) = @array_values(mysql_fetch_assoc($data));

            return true;
        } else {
            return false;
        }
    }

    public function isDataValid()
    {
        return (preg_match('/^[a-zA-Z0-9]{5,12}$/', $this->_username)
            && preg_match('/^[a-zA-Z0-9]{5,12}$/', $this->_password)
        ) ? 1 : 0;
    }

    public function isTokenValid()
    {
        return (
            !isset($_SESSION['token']) || $this->_token != $_SESSION['token']
        ) ? 0 : 1;
    }

    public function registerSession()
    {
        $_SESSION['ID'] = $this->_id;
        $_SESSION['username'] = $this->_username;
        $_SESSION['password'] = $this->_passmd5;
    }

    public function sessionExist()
    {
        return (isset($_SESSION['username']) && isset($_SESSION['password']))
            ? 1 : 0;
    }

    public function showErrors()
    {
        echo "<h3>Errors</h3>";

        foreach ($this->_errors as $key => $value)
            echo $value . "<br>";
    }
}
?>

如果缩进不正确，我道歉。此外，在/inc.all.php中，它所做的只是启动会话，连接到数据库，并选择适当的数据库。

没有任何错误或任何错误。唯一消失的是页脚。另外，我使用的是mysql，因为这仍然是一个概念。我完成后会切换到mysqli。

图片：Before Logging In After Logging In