Singleton类出了点问题，不知道怎么办 [英] Something wrong with Singleton class, no idea what

问题描述

我以前从来没有做过Singleton类，现在我发现对于这种数据库连接来说，建立一个是一个好主意，但是我不知道为什么它不起作用.如果有人愿意帮助我，我将不胜感激，因为我想学习OOP的工作原理...

I have never done any Singleton class before and now I figured that for this DB connection it will be a good idea to make one, but I have no clue why it is not working. I really would appreciate if someone would help me out with this one since I want to learn how OOP works...

无论如何，我只是通过将PHP更新到最新版本来修复它，现在$DBH = new static();可以正常工作，谢谢大家.

Anyway, I fixed it with just updating my PHP to latest version, now $DBH = new static(); works fine, thanks people.

我尝试使用$DBH = new self();的$DBH = new static(); istead，但随后出现此错误:

I tried to use $DBH = new static(); isntead of $DBH = new self(); but then I have this error:

解析错误:语法错误，意外 T_STATIC，预期为T_STRING或 T_VARIABLE或mSingleton.php中的"$" 第14行

Parse error: syntax error, unexpected T_STATIC, expecting T_STRING or T_VARIABLE or '$' in mSingleton.php on line 14

错误:

致命错误:无法实例化 中的抽象类Singleton 第14行的mSingleton.php

Fatal error: Cannot instantiate abstract class Singleton in mSingleton.php on line 14

文件: (mSingleton.php)

Files: (mSingleton.php)

abstract class Singleton
{

    protected $DBH;

    public static function getInstance()
    {
        if ($DBH == null)
        {
            $DBH = new self();
        }

        return $DBH;
    }

}

(mDBAccess.php)

(mDBAccess.php)

<?php
//mDBAccess.php
//Removed values ofc
$db_host = "";
$db_name = "";
$db_user = "";
$db_pass = "";

include "mSingleton.php";

class DBAccess extends Singleton
{
    protected $DBH;

    function __construct()
    {
        try
        {
        $this->DBH = new PDO("mysql:host=$db_host;dbname=$db_name", $db_user, $db_pass);
        $this->DBH->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING);
        }
        catch (PDOException $e)
        {
            echo $e->getMessage();
        }
    }

    public static function getDBH()
    {
        return self::getInstance()->DBH;
    }
}

(mLog.php)

<?php
//mLog.php
include "mDBAccess.php";

class Log
{

    public static function Add($action)
    {
        try
        {
            $DBH = DBAccess::getDBH();

            //Getting user IP
            $ip = $_SERVER['REMOTE_ADDR'];

            //Getting time
            $time = date('Y-m-d');

            //Preparing our SQL Query
            $values = array($ip, $action, $time);
            $STH = $DBH->prepare("INSERT INTO log (ip, action, time)
                                  VALUES (?, ?, ?)");

            //Excecuting SQL Query
            $STH->execute($values);
        }
        catch (PDOException $e)
        {
            echo $e->getMessage();
        }
    }

}
//testing..
Log::Add("ddd");

推荐答案

您需要编写

$DBH = new static();

请参阅:后期静态绑定

这篇关于Singleton类出了点问题，不知道怎么办的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！