设计模式---3种基本模式

<?php
//参考慕课网教程和下面的评论
namespace Imooc;
class Database
{
    private static $db;
    private $dbValue;
    //单例模式
    private function __construct()
    {

    }
    //私有化__clone，防止被克隆
    private function __clone()
    {

    }

    public static function getInstace()
    {
        if(self::$db){
            return self::$db;
        }else{
            self::$db = new self();
            return self::$db;
        }
        
    }
    public static function index()
    {
        var_dump(‘private self‘);
    }

    public function setValue($data)
    {
        $this->dbValue = $data;
    }

    public function getValue()
    {
        return $this->dbValue;
    }
}