Question

我刚刚创建了一个PHP类，我仍然围绕着课程以及它们如何工作。为什么我的“成功连接！”得到两次回声？我试过看过它并且无法理解为什么会打印两次。

            <?php


            include 'dbConfig.php';

            class dbConnect extends dbConfig
            {
                public $connectionString;
                public $dataSet;
                private $sqlQuery;

                    protected $host;
                    protected $userName;
                    protected $passWord;
                    protected $dbName;

                function dbParams(){
                    $this->connectionString = NULL;
                    $this->sqlQuery = NULL;
                    $this->dataSet = NULL;
                        // Creates an object that is created on the extend (dbConfig)
                        $dbParams = new dbConfig();

                        //Sets the variables in this class to match dbConfig's
                        $this->host = $dbParams->host;
                        $this->userName = $dbParams->userName;
                        $this->passWord = $dbParams->passWord;
                        $this->dbName = $dbParams->dbName;
                        // Object no longer needed, Null the object
                        $dbParams = NULL;
                }

                function dbConnect(){
                    $this ->connectionString = mysqli_connect($this->host, $this->userName, $this->passWord, $this->dbName);

                    if($this->connectionString->connect_error){
                        echo "Connection failed";
                    } else{
                        echo "Successfully Connected!";
                    }

                    return $this->connectionString;
                }
            }

Answer 1

因为您正在运行构造函数两次：

        class dbConnect extends dbConfig {
            function dbConnect(){

PHP支持使用类名作为构造方法的名称，这可以追溯到PHP获得对象支持的早期阶段，之前他们还添加了正式的__construct()版本。

因此，由于上述原因，您自动构造对象，然后使用以下内容构造另一个对象：

        $dbParams = new dbConfig();

PHP数据库类，回声两次

1 个答案: