Wordpress 在后台：文章列表和页面列表展示缩略图

//文章列表调用缩略图
 if ( !function_exists('fb_AddThumbColumn') && function_exists('add_theme_support') ) {
    
      在文章列表页与页面列表页添加缩略图列表
     add_theme_support('post-thumbnails', array( 'post', 'page' ) );
    
     function fb_AddThumbColumn($cols) {
        
         $cols['thumbnail'] = __('Thumbnail');
        
         return $cols;
     }
    
     function fb_AddThumbValue($column_name, $post_id) {
            
             $width = (int) 35;
             $height = (int) 35;
            
             if ( 'thumbnail' == $column_name ) {
                  thumbnail of WP 2.9
                 $thumbnail_id = get_post_meta( $post_id, '_thumbnail_id', true );
                  image from gallery
                 $attachments = get_children( array('post_parent' => $post_id, 'post_type' => 'attachment', 'post_mime_type' => 'image') );
                 if ($thumbnail_id)
                     $thumb = wp_get_attachment_image( $thumbnail_id, array($width, $height), true );
                 elseif ($attachments) {
                     foreach ( $attachments as $attachment_id => $attachment ) {
                         $thumb = wp_get_attachment_image( $attachment_id, array($width, $height), true );
                     }
                 }
                     if ( isset($thumb) && $thumb ) {
                         echo $thumb;
                     } else {
                         echo __('None');
                     }
             }
     }
    
      //文章页调用
     add_filter( 'manage_posts_columns', 'fb_AddThumbColumn' );
     add_action( 'manage_posts_custom_column', 'fb_AddThumbValue', 10, 2 );
    
      //页面调用
     add_filter( 'manage_pages_columns', 'fb_AddThumbColumn' );
     add_action( 'manage_pages_custom_column', 'fb_AddThumbValue', 10, 2 );
 }