WP获取中文摘要

function get_post_excerpt($post, $excerpt_length = 240)
{
  if (!$post) $post = get_post();

  $post_excerpt = $post->post_excerpt;
  if ($post_excerpt == '') {
    $post_content = $post->post_content;
    $post_content = do_shortcode($post_content);
    $post_content = wp_strip_all_tags($post_content);

    $post_excerpt = mb_strimwidth($post_content, 0, $excerpt_length, '…', 'utf-8');
  }

  $post_excerpt = wp_strip_all_tags($post_excerpt);
  $post_excerpt = trim(preg_replace("/[\n\r\t ]+/", ' ', $post_excerpt), ' ');

  return $post_excerpt;
}