Think/Upload.php
private function setDriver($driver = null, $config = null)
    {
        $driver = $driver ?: ($this->driver ?: C('FILE_UPLOAD_TYPE'));
        $config = $config ?: ($this->driverConfig ?: C('UPLOAD_TYPE_CONFIG'));
        $class = strpos($driver, '\\') ? $driver : 'Think\\Upload\\Driver\\'.ucfirst(strtolower($driver));
        $this->uploader = new $class($config);
        if (!$this->uploader) {
            throw new BaseException("不存在上传驱动：{$driver}");
        }
    }
private function setDriver($driver = null, $config = null)
    {
        $driver = $driver ?: ($this->driver ?: C('FILE_UPLOAD_TYPE'));
        $config = $config ?: ($this->driverConfig ?: C('UPLOAD_TYPE_CONFIG'));
        $class = strpos($driver, '\\') ? $driver : 'Think\\Upload\\Driver\\'.ucfirst(strtolower($driver));
        $this->uploader = new $class($config);
        if (!$this->uploader) {
            throw new BaseException("不存在上传驱动：{$driver}");
        }
    }
设置上传驱动

@param string $driver 驱动名称
@param array $config 驱动配置
@throws BaseException