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单例模式

<?php
class Db{
  static private $_instance;
  static private $_connectSource;
  private $_dbConfig = [
        ‘host‘ => ‘127.0.0.1‘,
        ‘user‘ => ‘root‘,
        ‘password‘ => ‘‘,
        ‘database‘ => ‘hanling‘
  ];

  private function __construct(){

  }

  static public function getInstance(){
    if(!(self::$_instance instanceof self)){
      self::$_instance = new self();
    }
    return self::$_instance;
  }

  public function connect(){
    if(!self::$_connectSource){
      self::$_connectSource = mysql_connect($this->_dbConfig[‘host‘],$this->_dbConfig[‘user‘],$this->_dbConfig[‘password‘]);
      if(!self::$_connectSource){
         die(‘mysql connect error‘.mysql_error());
      }
      mysql_select_db($this->_dbConfig[‘database‘],self::$_connectSource);
      mysql_query(‘set names utf8‘,self::$_connectSource);
    }
    return self::$_connectSource;
  }
}

$connect = Db::getInstance()->connect();
var_dump($connect);//资源

?>

单例模式