Question

我创建了一个数据库连接脚本，如下所示：

class DBManager{
static $connection;
public $dbh;
private $dbHost = null, $dbUser = null, $dbPass = null, $dbName= null;

private function __construct($dbDetails = array()){
    $this->dbHost = $dbDetails['db_host'];
    $this->dbName = $dbDetails['db_name'];
    $this->dbUser = $dbDetails['db_user'];
    $this->dbPass = $dbDetails['db_pass'];

    $this->dbh = new PDO("mysql:host=$this->dbHost;dbname = $this->dbName", $this->dbUser, $this->dbPass);
}

public static function init($dbDetails){
    if(isset(self::$connection)){
        return self::$connection;
    }
    else{
        return self::$connection = new DBManager($dbDetails);
    }
}
}

$dbDetails = array(
'db_host' => '127.0.0.1',
'db_name' => 'loura',
'db_user' => 'root',
'db_pass' => ''
);

我希望通过以下方式在我的其他课程中获得连接：

require_once('test.php');

class Data{

private $dbh;

public function __construct($dbDetails){
    $this->dbh = DBManager::init($dbDetails);
}

function getInfo(){
    $stmt = $this->dbh->prepare("SELECT * FROM user_master");
    $stmt->execute();
    return $stmt -> fetchAll();

}
}

我这样做是否正确？我试图在另一个类中调用静态方法，这是合法的吗？

编辑：这是我的错误：

致命错误：未捕获错误：调用未定义的方法DBManager :: prepare（）

Answer 1

DBManager类中存在类型多态问题：

{{1}}

Answer 2

我建议这样的事情。

// DBConfig.php
namespace App\Model\Db;

class DBConfig {
    public static $dbConfig = [
        'db_host' => '127.0.0.1',
        'db_name' => 'loura',
        'db_user' => 'root',
        'db_pass' => '',
    ];
}

// DBConnection.php
namespace App\Model\Db;

class DBConnection {
    private $dbh = null;
    private $dbHost = null, $dbUser = null, $dbPass = null, $dbName= null;

    public function getDbh()
    {
        return $this->dbh;
    }

    /**
     * Setting up connection on class create.
     */
    public function __construct($dbDetails = array()){
        $this->dbHost = $dbDetails['db_host'];
        $this->dbName = $dbDetails['db_name'];
        $this->dbUser = $dbDetails['db_user'];
        $this->dbPass = $dbDetails['db_pass'];

        $this->dbh = new PDO("mysql:host=$this->dbHost;dbname = $this->dbName", $this->dbUser, $this->dbPass);
   }
}

// DBManager.php
namespace App\Model\Db;

class DBManager {
    private $connection = null;

    public static getConnection()
    {
        if ($this->connection instanceof DBConnection) {
            return $this->connection;
        } else {
            $this-connection = new DBConnection(DBConfig::dbConfig);

            return $this->connection;
        }
    }
}

// Data.php
namespace App\Model\Data;

use App\Model\DBManager;

class Data {
    function getInfo(){
        $conn = DBManager::getConnection();
        $stmt = $conn->prepare("SELECT * FROM user_master");
        $stmt->execute();

        return $stmt -> fetchAll();
    }
}

Answer 3

return self::$connection = new DBManager($dbDetails);上有错误，此处返回的是DBManager个实例，而不是PDO个实例。

class DBManager{
static $connection;
public $dbh;
private $dbHost = null, $dbUser = null, $dbPass = null, $dbName= null;

private function __construct($dbDetails = array()){
    $this->dbHost = $dbDetails['db_host'];
    $this->dbName = $dbDetails['db_name'];
    $this->dbUser = $dbDetails['db_user'];
    $this->dbPass = $dbDetails['db_pass'];

    $this->dbh = new PDO("mysql:host=$this->dbHost;dbname = $this->dbName", $this->dbUser, $this->dbPass);
}

public static function init($dbDetails){
    if(isset(self::$connection)){
        return self::$connection;
    }
    else{
        self::$connection = new self($dbDetails);
        return self::$connection->dbh;
    }
}
}

但我建议使用以下class

/**
 * PDO database, only one connection is allowed.
 *
 */
class Db {

    //
    private $_dbh;

    // Store the single instance.
    private static $_instance;

    /**
     *  Get an instance of the database.
     *  @return Db.
     */
    public static function instance(){
        if( !self::$_instance ){
            self::$_instance = new self();
        }

        return self::$_instance->_dbh;
    }

    /**
     * Magic __construct.
     */
    function __construct(){
        try{
            $this->_dbh = new PDO( "mysql:host=".DB_HOST.";dbname=".DB_NAME.";charset=".DB_CHARSET, DB_USER, DB_PASSWORD );
        }catch( PDOException $e ){
            trigger_error( $e->getMessage().PHP_EOL, E_USER_ERROR );
            die( 'Error: Can\'t connect to the database.' );
        }
    }

    /**
     * Empty clone method to prevent duplication.
     */
    function __clone(){}
}

PHP：无法在另一个类中调用静态方法

3 个答案: