php单例模式

这个东西虽然早就看过，但经常不用又忘了。哎，很多东西需要不断的实践操作。。。。。。。。。。。。。

 

其实原理就是构造函数这里做判断，不让直接实例化。需要用静态STATIC变量作记录。私有化private

这是我自己随便写的：

1. class MyClass{
2. private static _instance;
3. private myClass(){}
4. public getInstance(){
5.   if(_instance == null){
6.   news myClass();  //实例化自身类，private在自己内中实例化
7. }
8. return _instance;
9. }
10. }

 

 

网摘一：

 

01	class User {

02	static function getInstance()

03

{

04	if (self::$instance == NULL) { // If instance is not created yet, will create it.

05	self::$instance = new User();

06

}

07	return self::$instance;

08

}

09	private function __construct()

10	// Constructor method as private  so by mistake developer not crate

11	// second object  of the User class with the use of new operator

12

{

13

}

14	private function __clone()

15	// Clone method as private so by mistake developer not crate

16	//second object  of the User class with the use of clone.

17

{

18

}

19

20	function Log($str)

21

{

22	echo $str;

23

}

24	static private $instance = NULL;

25

}

26	User::getInstance()->Log("Welcome User");

 

网摘二：

01	class User {

02	static function getInstance()

03

{

04	if (self::$instance == NULL) { // If instance is not created yet, will create it.

05	self::$instance = new User();

06

}

07	return self::$instance;

08

}

09	private function __construct()

10	// Constructor method as private  so by mistake developer not crate

11	// second object  of the User class with the use of new operator

12

{

13

}

14	private function __clone()

15	// Clone method as private so by mistake developer not crate

16	//second object  of the User class with the use of clone.

17

{

18

}

19

20	function Log($str)

21

{

22	echo $str;

23

}

24	static private $instance = NULL;

25

}

26	User::getInstance()->Log("Welcome User");