PHP 注册树模式

/**
 * 注册树模式
 * 将对象注册到一个类中
 * 通过该类实现全局访问操作对象
 */
class Tree
{
    private static $treeList = [];

    private function __construct(){}

    private function __clone(){}

    public static function set($key,$value)
    {
        //设置节
        self::$treeList[$key] = $value;
    }

    public static function get($key)
    {
        //获取节
        return self::$treeList[$key];
    }

    public static function delete($key)
    {
        //删除节
        unset(self::$treeList[$key]);
    }
}

class Mysql
{

}

class Slave
{

}

//注册对象
Tree::set('write',new Mysql());
Tree::set('read',new Slave());

//获取对象
Tree::get('read');

//删除对象
Tree::delete('write');