<?
class
mysql{
privete static $instance ;//保存实例
//
构造函数声明为private, 防止直接创建对象
privete function __construct(){
// 实例化
}
//单例方法, 判断是否已经实例化,只实例化一次
public static function getInstance (){
if(!isset( self::$instance )){
self ::$instance = new self();
}
return self:: $instance;
}
//防止克隆对象
private function __clone (){
trigger_error ("not allow to clone.");
}
function test(){
echo "test" ;
}
}
$conn = mysql::getInstance ();
$conn->test ();
?>