问如何在Wordpress的发布框内的编辑帖子页面中添加一个字段？

EN

add_action( 'post_submitbox_misc_actions', 'publish_in_frontpage' );
function publish_in_frontpage($post)
{
    $value = get_post_meta($post->ID, '_publish_in_frontpage', true);
    echo '<div class="misc-pub-section misc-pub-section-last">
         <span id="timestamp">'
         . '<label><input type="checkbox"' . (!empty($value) ? ' checked="checked" ' : null) . 'value="1" name="publish_in_frontpage" /> Publish to frontpage</label>'
    .'</span></div>';
}

function save_postdata($postid)
{   
    if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) return false;
    if ( !current_user_can( 'edit_page', $postid ) ) return false;
    if(empty($postid) || $_POST['post_type'] != 'article' ) return false;

    if($_POST['action'] == 'editpost'){
        delete_post_meta($postid, 'publish_in_frontpage');
    }

    add_post_meta($postid, 'publish_in_frontpage', $_POST['publish_in_frontpage']);
}