PHP开发中注册输入信息校验器的实现

/**
 * Validator for Register.
 */
final class RegisterValidator {
    private function __construct() {

    }
    /**
     * Validate the given username, password, repeat_password and email.
     * @param $username, $password, $repeat_password and $email to be validated
     * @return array array of {@link Error} s
     */
    public static function validate($username, $password, $repeat_password, $email) {
        $errors = array();
        $username = trim($username);
        $password = trim($password);
        if (!$username) {
            $errors[] = new Error('username', '用户名不能为空。');
        } elseif (strlen($username)             $errors[] = new Error('username', '用户名长度不能小于3个字符。');
        } elseif (strlen($username)>30) {
            $errors[] = new Error('username', '用户名长度不能超过30个字符。');
        } elseif (!preg_match('/^[A-Za-z]+$/',substr($username, 0, 1))) {
            $errors[] = new Error('username', '用户名必须以字母开头。');
        } elseif (!preg_match('/^[A-Za-z0-9_]+$/', $username)) {
            $errors[] = new Error('username', '用户名只能是字母、数字以及下划线( _ )的组合。');
        } elseif (!$password) {
            $errors[] = new Error('password', '密码不能为空。');
        } elseif (strlen($password)             $errors[] = new Error('password', '密码长度不能小于6个字符。');
        } elseif (strlen($password)>30) {
            $errors[] = new Error('password', '密码长度不能超过30个字符。');
        } elseif (!preg_match('/^[A-Za-z0-9!@#\\$%\\^&\\*_]+$/', $password)) {
            $errors[] = new Error('password', '密码只能是数字、字母或!@#$%^&*_等字符的组合。');
        } elseif ($password != trim($repeat_password)) {
            $errors[] = new Error('password', '两次输入密码不一致。');
        } elseif (!Utils::isValidEmail($email)) {
            $errors[] = new Error('email', '邮箱格式有误。');
        } else {
            // check whether user exists or not
            $dao = new UserDao();
            $user = $dao->findByName(trim($username));
            if ($user) {
                $errors[] = new Error('username', '该用户名已经被使用。');
            }

            $user = null;
            // check whether email being used or not
            $user = $dao->findByEmail(trim($email));
            if ($user) {
                $errors[] = new Error('email', '该邮箱已被注册。');
            }
        }
        return $errors;
    }
}
?>

$username = null;
$password = null;
$repeat_password = null;
$email = null;
$msg = "";
if (isset($_POST['username']) && isset($_POST['password'])
        && isset($_POST['repeat_password']) && isset($_POST['email'])) {
    $username = addslashes(trim(stripslashes($_POST ['username'])));
    $password = addslashes(trim(stripslashes($_POST ['password'])));
    $repeat_password = addslashes(trim(stripslashes($_POST ['repeat_password'])));
    $email = addslashes(trim(stripslashes($_POST ['email'])));
    // validate
    $errors = RegisterValidator::validate($username, $password, $repeat_password, $email);
    // validate
    if (empty($errors)) {
        // save
        $dao = new UserDao();
        $user = new User();
        $user->setEmail($email);
        $last_login_ip = Utils::getIpAddress();
        $user->setLastLoginIp($last_login_ip);
        $user->setUsername($username);
        $salt = substr(sha1(mt_rand()), 0, 22);
        $hash_password = sha1($salt . $password);
        $user->setPassword($hash_password);
        $user->setSalt($salt);
        $user = $dao->save($user);
        if ($user) {
            UserLogin::setUserInfo($user);
            Flash::addFlash('注册成功！');
        }
        else {
            Flash::addFlash('对不起，由于服务器内部错误，导致注册失败。请稍后再试。');
        }
        Utils::redirect('welcome');
    }

    foreach ($errors as $e) {
        $msg .= $e->getMessage()."
";
    }