- <?php
- class SqlHelper
- {
- private static $_instance;
- public $_dbname;
- private function __construct()
- {
- }
- //getInstance()方法必须设置为公有的,必须调用此方法
- public static function getInstance()
- {
- //对象方法不能访问普通的对象属性,所以$_instance需要设为静态的
- if (self::$_instance === null) {
- // self::$_instance=new SqlHelper();//方式一
- self::$_instance = new self(); //方式二
- }
- return self::$_instance;
- }
- public function getDbName()
- {
- echo $this->_dbname;
- }
- public function setDbName($dbname)
- {
- $this->_dbname = $dbname;
- }
- }
- // $sqlHelper=new SqlHelper();//打印:Fatal error: Call to private SqlHelper::__construct() from invalid context
- $A = SqlHelper::getInstance();
- $A->setDbName('数据库名');
- $A->getDbName();
- // unset($A);//移除引用
- $B = SqlHelper::getInstance();
- $B->getDbName();
- $C = SqlHelper::getInstance();
- $C->getDbName();
- ?>
来源: http://www.phpxs.com/code/1003510/