多例模式

<?php

class Multiton
{
    private static $conn = [];

    private function __construct()
    {

    }

    private function __clone()
    {

    }

    private function __wakeup()
    {

    }

    public static function getConn($type)
    {
        if (!array_key_exists($type, self::$conn)) {
            self::$conn[$type] = new self();
        }

        return self::$conn[$type];
    }
}