Detailed explanation of PHP singleton mode demo
This article mainly shares with you the singleton mode demo of PHP design pattern, hoping to help everyone learn the PHP singleton mode better.
<?php/** * 设计模式之单例模式 * $_instance必须声明为静态的私有变量 * 构造函数和析构函数必须声明为私有,防止外部程序new * 类从而失去单例模式的意义 * getInstance()方法必须设置为公有的,必须调用此方法 * 以返回实例的一个引用 * ::操作符只能访问静态变量和静态函数 * new对象都会消耗内存 * 使用场景:最常用的地方是数据库连接。 * 使用单例模式生成一个对象后, * 该对象可以被其它众多对象所使用。 */class Example{//保存例实例在此属性中 private static $_instance;//构造函数声明为private,防止直接创建对象 public function __construct() { //初始的方法 }//单例方法 public static function getInstance() { if(!isset(self::$_instance)) { $c=__CLASS__; self::$_instance=new $c; } return self::$_instance; } function test() { echo("test"); } }// 这个写法会出错,因为构造方法被声明为private//$test = new Example;// 下面将得到Example类的单例对象$test = Example::getInstance();$test->test();?>
<?php/** * 设计模式之单例模式 * $_instance必须声明为静态的私有变量 * 构造函数和析构函数必须声明为私有,防止外部程序new * 类从而失去单例模式的意义 * getInstance()方法必须设置为公有的,必须调用此方法 * 以返回实例的一个引用 * ::操作符只能访问静态变量和静态函数 * new对象都会消耗内存 * 使用场景:最常用的地方是数据库连接。 * 使用单例模式生成一个对象后, * 该对象可以被其它众多对象所使用。 */class Example{//保存例实例在此属性中 private static $_instance;//构造函数声明为private,防止直接创建对象 public function __construct() { //初始的方法 }//单例方法 public static function getInstance() { if(!isset(self::$_instance)) { $c=__CLASS__; self::$_instance=new $c; } return self::$_instance; } function test() { echo("test"); } }// 这个写法会出错,因为构造方法被声明为private//$test = new Example;// 下面将得到Example类的单例对象$test = Example::getInstance();$test->test();?>
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