让WordPress的分类,标签等存档页能单独置顶文章

WordPress中有原生的文章置顶功能，不过只能支持在首页让置顶文章在顶部显示，其他如：分类页、标签页、作者页和日期页等存档页面，则无法实现置顶功能。
例如：想要实现在每个分类下单独置顶一些文章而不显示其它分类下的文章的功能原生是没有的。
为了实现这样的单独置顶功能，有两种方式：插件方式和直接修改代码方式。
（1）插件方式
目前在WordPress4.1.1版本测试过可行的方式是，采用插件Category Sticky Post。
此插件在后台插件页面搜索安装启用后，会在文章编辑页面增加一项选择置顶分类的选项，选择需要置顶的分类即可。下图为选择页面：

（2）代码方式
把下面的代码放到当前主题下的functions.php中就可以了：

add_filter('the_posts',  'putStickyOnTop' );
function putStickyOnTop( $posts ) {
  if(is_home() || !is_main_query() || !is_archive())
    return $posts;
  global $wp_query;
  // 获取所有置顶文章
  $sticky_posts = get_option('sticky_posts');
  if ( $wp_query->query_vars['paged'] <= 1 && !emptyempty($sticky_posts) && is_array($sticky_posts) && !get_query_var('ignore_sticky_posts') ) {
    $stickies1 = get_posts( array( 'post__in' => $sticky_posts ) );
    foreach ( $stickies1 as $sticky_post1 ) {
      // 判断当前是否分类页 
      if($wp_query->is_category == 1 && !has_category($wp_query->query_vars['cat'], $sticky_post1->ID)) {
        // 去除不属于本分类的置顶文章
        $offset1 = array_search($sticky_post1->ID, $sticky_posts);
        unset( $sticky_posts[$offset1] );
      }
      if($wp_query->is_tag == 1 && !has_tag($wp_query->query_vars['tag'], $sticky_post1->ID)) {
        // 去除不属于本标签的文章
        $offset1 = array_search($sticky_post1->ID, $sticky_posts);
        unset( $sticky_posts[$offset1] );
      }
      if($wp_query->is_year == 1 && date_i18n('Y', strtotime($sticky_post1->post_date))!=$wp_query->query['m']) {
        // 去除不属于本年份的文章
        $offset1 = array_search($sticky_post1->ID, $sticky_posts);
        unset( $sticky_posts[$offset1] );
      }
      if($wp_query->is_month == 1 && date_i18n('Ym', strtotime($sticky_post1->post_date))!=$wp_query->query['m']) {
        // 去除不属于本月份的文章
        $offset1 = array_search($sticky_post1->ID, $sticky_posts);
        unset( $sticky_posts[$offset1] );
      }
      if($wp_query->is_day == 1 && date_i18n('Ymd', strtotime($sticky_post1->post_date))!=$wp_query->query['m']) {
        // 去除不属于本日期的文章
        $offset1 = array_search($sticky_post1->ID, $sticky_posts);
        unset( $sticky_posts[$offset1] );
      }
      if($wp_query->is_author == 1 && $sticky_post1->post_author != $wp_query->query_vars['author']) {
        // 去除不属于本作者的文章
        $offset1 = array_search($sticky_post1->ID, $sticky_posts);
        unset( $sticky_posts[$offset1] );
      }
    }
    $num_posts = count($posts);
    $sticky_offset = 0;
    // Loop over posts and relocate stickies to the front.
    for ( $i = 0; $i < $num_posts; $i++ ) {
      if ( in_array($posts[$i]->ID, $sticky_posts) ) {
        $sticky_post = $posts[$i];
        // Remove sticky from current position
        array_splice($posts, $i, 1);
        // Move to front, after other stickies
        array_splice($posts, $sticky_offset, 0, array($sticky_post));
        // Increment the sticky offset. The next sticky will be placed at this offset.
        $sticky_offset++;
        // Remove post from sticky posts array
        $offset = array_search($sticky_post->ID, $sticky_posts);
        unset( $sticky_posts[$offset] );
      }
    }
    // If any posts have been excluded specifically, Ignore those that are sticky.
    if ( !emptyempty($sticky_posts) && !emptyempty($wp_query->query_vars['post__not_in'] ) )
      $sticky_posts = array_diff($sticky_posts, $wp_query->query_vars['post__not_in']);
    // Fetch sticky posts that weren't in the query results
    if ( !emptyempty($sticky_posts) ) {
      $stickies = get_posts( array(
        'post__in' => $sticky_posts,
        'post_type' => $wp_query->query_vars['post_type'],
        'post_status' => 'publish',
        'nopaging' => true
      ) );
      foreach ( $stickies as $sticky_post ) {
        array_splice( $posts, $sticky_offset, 0, array( $sticky_post ) );
        $sticky_offset++;
      }
    }
  }
  return $posts;
}