PHP设计模式(3）-单例模式

<?php

header("Content-type: text/html; charset=utf-8");

class Singleton{

privatestatic$instance;

privatefunction __construct(){}

staticfunction GetInstance(){

if(empty(self::$instance)){

self::$instance=new Singleton();

}

return self::$instance;

}

}

$s1=Singleton::GetInstance();

$s2=Singleton::GetInstance();

if($s1===$s2){

echo"这是两个相同的实例";

}

else{

echo"这两个实例不同";

}