單例模式解決的是如何在整個(gè)項(xiàng)目中創(chuàng)建唯一對(duì)象實(shí)例的問(wèn)題，工廠模式解決的是如何不通過(guò)new建立實(shí)例對(duì)象的方法。
單例模式可以換成數(shù)據(jù)庫(kù)類，數(shù)據(jù)庫(kù)類再擴(kuò)展做成 “適配器模式”

<?php
//創(chuàng)建單例
class Single{
    public $hash;
    static protected $ins=null;
    final protected function __construct(){
        $this->hash=rand(1,9999);
    }

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

//工廠模式
class RandFactory{
    public static function factory(){
        return Single::getInstance();
    }
}

//注冊(cè)樹(shù)
class Register{
    protected static $objects;
    public static function set($alias,$object){
        self::$objects[$alias]=$object;
    }
    public static function get($alias){
        return self::$objects[$alias];
    }
    public static function _unset($alias){
        unset(self::$objects[$alias]);
    }
}

Register::set('rand',RandFactory::factory());

$object=Register::get('rand');

print_r($object);