Php 具有pdo的DB类在继承时不应重新启动连接

当我在一个数据库中调用不同的模型，然后多次建立数据库连接时，我只需要一个，这是可能的。下面是我的mvc的一部分

class Database{
    private $db;
    private $stmt;
    function __construct()
    {
        parent::__construct();
        $root = dirname(dirname(__FILE__));
        $this->config = parse_ini_file($root . '/app/config.ini', true);

        $db = $this->config['database settings'];
        $host = $db['host'];
        $user = $db['user'];
        $pword = $db['pword'];
        $db_name = $db['db'];
        $this->db = new PDO("mysql:host=$host;dbname=$db_name", $user, $pword, array(
            PDO::MYSQL_ATTR_FOUND_ROWS => true, PDO::ATTR_PERSISTENT => true
        ));
        $this->db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        $this->db->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);        
    }
    function executeQuery($query, $params = array())
    {
         $this->stmt = $this->db->prepare($query);
         if (! ($this->stmt)) {
           throw new Exception('Query failed while preparing');
         }
         try {
            $this->stmt->execute($params);
         } catch (PDOException $e) {
            throw $e;
         }
     }
     function getRecords($query, $params = array(), $array = false, $all = false)
     {
          $this->executeQuery($query, $params);

           $records = array();
          if ($this->totalRecords() > 0) {
             if ($array) {
                $this->stmt->setFetchMode(PDO::FETCH_ASSOC);
             } else {
                 $this->stmt->setFetchMode(PDO::FETCH_OBJ);
             }
            if ($all) {
               $records = $this->stmt->fetchAll();
            } else {
                while (($record = $this->stmt->fetch()) !== false) {
                   $records[] = $record;
               }
           }
        }
        return $records;
     }
  }

下面是我使用它的模型

class TestModel extends Database{
  function __construct(){
    parent::__construct();
  }
  function getUsers(){
     return $this->getRecords("SELECT * FROM users");
  }
}

下面是另一个模型，我想调用getusers方法将其用于某些目的

require("path_to_testmodel"); 
require("path_to_some_model");
require("path_to_some_other_model");
class TestModel2 extends Database{
    function __construct(){
       parent::__construct();
       $this->test_model = new TestModel();
       $this->some_model = new SomeModel();
       $this->some_other_model = new SomeOtherModel();
    }
    function doSomething(){
       $users = $this->test_model->getUsers();
    }
}

如果我在其中一个模型中包括多个模型，比如TestModel（），这里看到的是每次建立数据库连接时，有时会出现连接过多的错误，或者在某些系统中会出现内存分配问题

---

请帮助我修复此问题。

尝试将您的数据库连接保存在中

请注意，这将导致连接在脚本结束时关闭，而不是在对象销毁时关闭。对于大多数用例来说这是可以的，但是如果您想更早地断开与数据库的连接，您需要跟踪您有多少个对象，并在数量为0时销毁连接

class Database{
    static private $theOnlyConnection = null;
    static private $modelObjectCount = 0;
    private $db;
    private $stmt;

    public function __construct()
    {
        self::$modelObjectCount++;
        if(null === self::$theOnlyConnection) {
            // connect
        }

        $this->db = self::$theOnlyConnection;
    }

    public function __destruct() {
        self::$modelObjectCount--;
        if(0 == self::$modelObjectCount) {
            // close connection
            self::$theOnlyConnection = null;
        }
    }

这可能会有帮助。

class Database{
    static private $theOnlyConnection = null;
    static private $modelObjectCount = 0;
    private $db;
    private $stmt;

    public function __construct()
    {
        self::$modelObjectCount++;
        if(null === self::$theOnlyConnection) {
            // connect
        }

        $this->db = self::$theOnlyConnection;
    }

    public function __destruct() {
        self::$modelObjectCount--;
        if(0 == self::$modelObjectCount) {
            // close connection
            self::$theOnlyConnection = null;
        }
    }