Question

导致问题的系统的另一部分，问题已经解决

public static function getParticpantsIdsWithTitles(array $proftitlecodes)
{
     //connect_mysqli is a singleton, but everytime this is called a new instance is created
    $sqlconn = connect_mysqli::get_instance();
}

//All of these method calls cause the constructor of connect_mysqli to run

Participant::getParticpantsIdsWithTitles(array(1,2,3));    
Participant::getParticpantsIdsWithTitles(array(1,2,3));

从静态函数中使用它时，是否存在一些我不了解单例的规则？每次都会创建一个新的mysqli_object。（仅限静态函数）。它可以从非静态函数中正常工作。

private static $instance = FALSE;
  var  $host ;
  var  $dbUser ;
  var  $dbPass ;
  var  $dbName ;
  var  $dbConn ;
  var  $dbconnectError ;
  var  $query;
  var  $result;
  var  $row;

    function __construct () 
    {
        $this->host   = 'host' ;
        $this->dbUser = 'user' ;
        $this->dbPass = 'password' ;
        $this->dbName = 'db' ;
        $this->dbConn = new mysqli($this->host , $this->dbUser , $this->dbPass, $this->dbName )  ;

        file_put_contents("/Library/WebServer/Documents/test.txt", "CONNECT\n", FILE_APPEND);
        if ( !$this->dbConn )
        {
            trigger_error ('could not connect to server' ) ;
            $this->dbconnectError = true ;
        }
    }

    public static function get_instance()
    {
        if(!self::$instance)
        {
            self::$instance = new connect_mysqli();
        }

        return self::$instance;
    }

Answer 1

我无法重现你的问题。以下代码打印

创建了一个新的connect_mysqli

一次。

class foo 
{
  public static function getParticpantsIdsWithTitles(array $proftitlecodes)
  {
    $sqlconn = connect_mysqli::get_instance();
  }
}

class connect_mysqli
{
  private static $instance = FALSE;

  public function __construct()
  {
    echo "A new connect_mysqli was created\n";
  }

  public static function get_instance()
  {
    if(!self::$instance)
    {
      self::$instance = new connect_mysqli();
    }
    return self::$instance;
  }
}

for ($i = 0; $i < 10; ++$i)
{
  foo::getParticpantsIdsWithTitles(array());
}

Answer 2

我无法重现你的问题，但我确实注意到你的单身人士：

function __construct ()

这会将__construct()方法默认为public可见性。通常，单例的构造函数将被标记为private，以防止在提供的get_instance()方法之外进行实例化。

您确定只使用get_instance()而从不执行$mysqli = new connect_mysqli()之类的操作吗？您是否还确定不是从单例之外的上下文创建数据库连接？

单例不适用于静态函数

2 个答案: