您需要本地路径才能添加附件：

// add the file to the media library
$attachment = array(
    \'post_mime_type\' => \'image/png\' // the MIME type
,   \'post_title\'     => \'Attachment title\'
);

// Adds the file to the media library and generates the thumbnails.
$attach_id = wp_insert_attachment( $attachment, $path ); // PATH!