PHP开发APP接口----单例模式连接数据库

 <?php
 //单例模式
  class Db{
        static private $_instance;
        static private $_connectSource;
        private $_dbConfig=array(
            'host'=>'localhost',
            'user'=>'root',
            'passward'=>'111',
            'database'=>'db_database12',
        );
        private function __construct(){
       }
       static public function getInstance(){ //相当于单例模式的一个入口
           if(!(self::$_instance instanceof self)){  //instanceof:它的作用是判断其左边对象是否为其右边类的实例，返回boolean类型的数据。
           self::$_instance=new self();
           }
           return self::$_instance;
       }
       public function connect(){
           if(!self::$_connectSource){
                 self::$_connectSource=  mysql_connect($this->_dbConfig['host'],$this->_dbConfig['user'],$this->_dbConfig['passward']);
                 if(!self::$_connectSource){
                     die('mysql connect error'.mysql_error());
                 }
                 mysql_select_db($this->_dbConfig['database'],self::$_connectSource);
                 mysql_query('set names gbk',self::$_connectSource);
           }
                 return self::$_connectSource;
       }
  }
    $connect= Db::getInstance()->connect();
    $sql="select *from tb_demo01";
    $result=mysql_query($sql,$connect);     --------------》》》》 $arry=array();
    $arr=mysql_fetch_row($result);                                while($arr=mysql_fetch_row($result)){
    var_dump($arr);                                               $arry[]=$arr;
                                                                  }
                                                                    var_dump($arry);