<?php
class DBCxn{
    public static $dsn = 'mysql:host=localhost;dbname=webrss';
    public static $user = 'root';
    public static $pass = 'root';
    //保存连接的内部变量
    private static $db;
    //不能克隆和技巧化
    final private function __construct(){}
    final private function __clone(){}

    public static function get(){
        if(is_null(self::$db)){
            self::$db = new PDO(self::$dsn, self::$user, self::$pass);
        }
        //返回连接
        self::$db->query('set names utf8');
        return self::$db;
    }
}
?>