PHP开发APP接口----单例模式连接数据库

 1 <?php
 2 //单例模式
 3  class Db{
 4        static private $_instance;
 5        static private $_connectSource;
 6        private $_dbConfig=array(
 7            ‘host‘=>‘localhost‘,
 8            ‘user‘=>‘root‘,
 9            ‘passward‘=>‘111‘,
10            ‘database‘=>‘db_database12‘,
11        );
12        private function __construct(){  
13       } 
14       static public function getInstance(){ //相当于单例模式的一个入口
15           if(!(self::$_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。
16           self::$_instance=new self();
17           }    
18           return self::$_instance;
19       }
20       public function connect(){
21           if(!self::$_connectSource){
22                 self::$_connectSource=  mysql_connect($this->_dbConfig[‘host‘],$this->_dbConfig[‘user‘],$this->_dbConfig[‘passward‘]);
23                 if(!self::$_connectSource){
24                     die(‘mysql connect error‘.mysql_error());
25                 }  
26                 mysql_select_db($this->_dbConfig[‘database‘],self::$_connectSource);
27                 mysql_query(‘set names gbk‘,self::$_connectSource);
28           }
29                 return self::$_connectSource;
30       }
31  }
32    $connect= Db::getInstance()->connect();
33    $sql="select *from tb_demo01";
34    $result=mysql_query($sql,$connect);
35    $arr=mysql_fetch_row($result);
36    var_dump($arr);
37