abstract：<?phpclass Hubby{ private function __construct(){} private function __clone(){} protected static $instance=null; public static function getInstance() { if (is_null(static::$instance)){ static::$

<?php

class Hubby

{

private function __construct(){}

private function __clone(){}

protected static $instance=null;

public static function getInstance()

{

if (is_null(static::$instance)){

static::$instance=new static();

}

return static::$instance;

}

}

$hubby1=Hubby::getInstance();

$hubby2=Hubby::getInstance();

echo( $hubby1 instanceof hubby)?'是':'不是';

echo '<br>';

echo( $hubby2 instanceof hubby)?'是':'不是';

echo '<br>';

echo($hubby1===$hubby2)?'完全相等':'不相等';

echo '<br>';

var_dump($hubby1,$hubby2);

Correcting teacher：天蓬老師Correction time：2019-06-13 17:07:25
Teacher's summary：單例模式的應(yīng)用場(chǎng)景 還是很多... 很多類,為了效率, 不允許多重實(shí)例化