Question

我创建一个单例类以返回数据库连接。我唯一要做的就是从另一个php文件调用它的getInstance()函数。

这是单例文件：

<?php

namespace stm_asc;

class PDO_Conn
{
    public static $instance;

    private static $host = '127.0.0.1';
    private static $db   = 'stm_asc';
    private static $charset = 'utf8mb4';
    private static $user = 'alekrabbe';
    private static $pass = '<password>';

    private static $dsn;
    private static $opt = [
        PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
        PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
        PDO::ATTR_EMULATE_PREPARES   => false,
    ];

    private function __construct() {
        //
    }

    public static function getInstance() {
        if (!isset(self::$instance)) {
            try {
                self::$dsn = "mysql:host=".self::$host.";dbname=".self::$db.";charset=".self::$charset.";";
                self::$instance = new PDO(self::$dsn, self::$user, self::$pass, self::$opt);
                echo "Connected successfully";
            } catch(PDOException $e) {
                echo "Connection failed: " . $e->getMessage();
            }
        }

        return self::$instance;
    }
}

然后我从login.php中调用函数getInstance()，如下所示：

<?php
error_reporting(E_ALL);
ini_set("display_errors","On");
$pdo = \stm_asc\PDO_Conn::getInstance();
//session_start();    
?>

<!DOCTYPE html>
<html>
 [HTML CODE HERE]
</html>

但是当我尝试面包login.php时，出现以下错误：

Fatal error: Uncaught Error: Class 'stm_asc\PDO_Conn' not found in /home/alekrabbe/PhpstormProjects/selectorHat/views/login.php:4 Stack trace: #0 {main} thrown in /home/alekrabbe/PhpstormProjects/selectorHat/views/login.php on line 4

我不确定为什么找不到类PDO_Conn，这是我的目录结构：

如果我在$pdo = \stm_asc\PDO_Conn::getInstance();行中添加注释，则一切正常。

我正在使用PHP 7.2.7和Ubuntu 18.04

编辑1

因此，我尝试按照此documentation使用自动加载器。但是仍然无法正常工作，下面是代码：

<?php
session_start();
spl_autoload_register(function ($name) {
    echo "Want to load $name.\n";
    throw new Exception("Unable to load $name.");
});

try {
    $pdo = \stm_asc\PDO_Conn::getInstance();
    $mapper = new \stm_asc\MySQL_DataMapper($pdo);
    $stuff = $mapper->fetchUserByFname('Alexandre');
    var_dump($stuff);
} catch (Exception $e) {
    echo $e->getMessage(), "\n";
}   


?>

<!DOCTYPE html>
<html>
 [HTML CODE HERE]
</html>

这是显示在屏幕上的消息：

Want to load stm_asc\PDO_Conn. Unable to load stm_asc\PDO_Conn.

但是现在正在加载html，css和java脚本，我相信这是由于try catch块引起的。

我还尝试仅在login.php的开头添加require_once '../controller/database/PDO_Conn.php';，所以看起来像这样：

<?php
require_once '../controller/database/PDO_Conn.php';
$pdo = \stm_asc\PDO_Conn::getInstance();
?>

<!DOCTYPE html>
<html>
 [HTML CODE HERE]
</html>

但错误仍然存在：

Fatal error: Uncaught Error: Class 'stm_asc\PDO_Conn' not found in /home/alekrabbe/PhpstormProjects/selectorHat/views/login.php:22 Stack trace: #0 {main} thrown in /home/alekrabbe/PhpstormProjects/selectorHat/views/login.php on line 22

Answer 1

解决方案1：在您的login.php中加入课程。

<?php 
require_once '../path/to/file.php';

在您的情况下：（来自login.php）

<?php 
require_once '../controller/database/PDO_Conn.php';

解决方案2 ：（推荐）

使用PHP自动加载器：see this simple autoload example I set for you in GitHub.

其他资源：how-do-i-use-php-namespaces-with-autoload

在<path>中找不到PHP类

编辑1

1 个答案: