????static?function?getDatabase($id?=?'proxy')
????{
????????if?($id?==?'proxy')
????????{
????????????if?(!self::$proxy)
????????????{
????????????????self::$proxy?=?new?\IMooc\Database\Proxy;
????????????}
????????????return?self::$proxy;
????????}
?
????????$key?=?'database_'.$id;
????????if?($id?==?'slave')
????????{
????????????$slaves?=?Application::getInstance()->config['database']['slave'];
????????????$db_conf?=?$slaves[array_rand($slaves)];
????????}
????????else
????????{//這里單例出來的只是配置信息
????????????$db_conf?=?Application::getInstance()->config['database'][$id];
????????}
????????$db?=?Register::get($key);
????????if?(!$db)?{
????????????$db?=?new?Database\MySQLi();
???????????//根據配置信息實例$db,并儲存到注冊器數組中
????????????$db->connect($db_conf['host'],?$db_conf['user'],?$db_conf['password'],?$db_conf['dbname']);
????????????Register::set($key,?$db);
????????}
????????return?$db;
????}

第二個問題問什么？