这两种都是可能的。

使用将附件插入媒体库wp_insert_attachment function, 您可以将上载的图像插入媒体库。

以下是文档中的示例代码：

<?php
  $wp_filetype = wp_check_filetype(basename($filename), null );
  $wp_upload_dir = wp_upload_dir();
  $attachment = array(
     \'guid\' => $wp_upload_dir[\'baseurl\'] . _wp_relative_upload_path( $filename ), 
     \'post_mime_type\' => $wp_filetype[\'type\'],
     \'post_title\' => preg_replace(\'/\\.[^.]+$/\', \'\', basename($filename)),
     \'post_content\' => \'\',
     \'post_status\' => \'inherit\'
  );
  $attach_id = wp_insert_attachment( $attachment, $filename, 37 );
  // you must first include the image.php file
  // for the function wp_generate_attachment_metadata() to work
  require_once(ABSPATH . \'wp-admin/includes/image.php\');
  $attach_data = wp_generate_attachment_metadata( $attach_id, $filename );
  wp_update_attachment_metadata( $attach_id, $attach_data );
?>

更改上载目录要更改上载目录，您需要使用upload_dir 滤器Yoast has a pretty good tutorial 关于如何做到这一点。

add_filter(\'upload_dir\', \'my_upload_dir\');
$upload = wp_upload_dir();
remove_filter(\'upload_dir\', \'my_upload_dir\');

function my_upload_dir($upload) {
    $upload[\'subdir\']   = \'/sub-dir-to-use\' . $upload[\'subdir\'];
    $upload[\'path\']     = $upload[\'basedir\'] . $upload[\'subdir\'];
    $upload[\'url\']      = $upload[\'baseurl\'] . $upload[\'subdir\'];
    return $upload;
}