WordPress 面包屑导航Breadcrumbs 非插件实现

面包屑导航对于一个网站SEO来说还是挺重要的，可以使用以下代码来给自己的主题添加面包屑，将以下代码加入到主题的functions.php里：

function MBThemes_breadcrumbs() {
 /* === OPTIONS === */
 $text['home'] = '首页'; 
 $text['category'] = '%s'; 
 $text['search'] = '搜索结果：%s'; 
 $text['tag'] = '标签：%s'; 
 $text['author'] = '作者：%s'; 
 $text['404'] = '404'; 
 $text['page'] = '%s'; 
 $text['cpage'] = '%s'; 
 $wrap_before = '<div class="breadcrumbs">'; 
 $wrap_after = '</div>'; 
 $sep = '>'; 
 $sep_before = '<span class="sep">'; 
 $sep_after = '</span>'; 
 $show_home_link = 1; 
 $show_on_home = 0; 
 $show_current = 1;
 $before = '<span class="current">'; 
 $after = '</span>';
 /* === END OF OPTIONS === */
 global $post;
 $home_link = home_url('/');
 $link_before = '<span itemscope itemtype="http://data-vocabulary.org/Breadcrumb">';
 $link_after = '</span>';
 $link_attr = ' itemprop="url"';
 $link_in_before = '<span itemprop="title">';
 $link_in_after = '</span>';
 $link = $link_before . '<a href="%1$s"' . $link_attr . '>' . $link_in_before . '%2$s' . $link_in_after . '</a>' . $link_after;
 $frontpage_id = get_option('page_on_front');
 $parent_id = $post->post_parent;
 $sep = ' ' . $sep_before . $sep . $sep_after . ' ';
 if (is_home() || is_front_page()) {
 if ($show_on_home) echo $wrap_before . '<a href="' . $home_link . '">' . $text['home'] . '</a>' . $wrap_after;
 } else {
 echo $wrap_before;
 if ($show_home_link) echo sprintf($link, $home_link, $text['home']);
 if ( is_category() ) {
 $cat = get_category(get_query_var('cat'), false);
 if ($cat->parent != 0) {
 $cats = get_category_parents($cat->parent, TRUE, $sep);
 $cats = preg_replace("#^(.+)$sep$#", "$1", $cats);
 $cats = preg_replace('#<a([^>]+)>([^<]+)<\/a>#', $link_before . '<a$1' . $link_attr .'>' . $link_in_before . '$2' . $link_in_after .'</a>' . $link_after, $cats);
 if ($show_home_link) echo $sep;
 echo $cats;
 }
 if ( get_query_var('paged') ) {
 $cat = $cat->cat_ID;
 echo $sep . sprintf($link, get_category_link($cat), get_cat_name($cat)) . $sep . $before . sprintf($text['page'], get_query_var('paged')) . $after;
 } else {
 if ($show_current) echo $sep . $before . sprintf($text['category'], single_cat_title('', false)) . $after;
 }
 } elseif ( is_search() ) {
 if (have_posts()) {
 if ($show_home_link && $show_current) echo $sep;
 if ($show_current) echo $before . sprintf($text['search'], get_search_query()) . $after;
 } else {
 if ($show_home_link) echo $sep;
 echo $before . sprintf($text['search'], get_search_query()) . $after;
 }
 } elseif ( is_day() ) {
 if ($show_home_link) echo $sep;
 echo sprintf($link, get_year_link(get_the_time('Y')), get_the_time('Y')) . $sep;
 echo sprintf($link, get_month_link(get_the_time('Y'), get_the_time('m')), get_the_time('F'));
 if ($show_current) echo $sep . $before . get_the_time('d') . $after;
 } elseif ( is_month() ) {
 if ($show_home_link) echo $sep;
 echo sprintf($link, get_year_link(get_the_time('Y')), get_the_time('Y'));
 if ($show_current) echo $sep . $before . get_the_time('F') . $after;
 } elseif ( is_year() ) {
 if ($show_home_link && $show_current) echo $sep;
 if ($show_current) echo $before . get_the_time('Y') . $after;
 } elseif ( is_single() && !is_attachment() ) {
 if ($show_home_link) echo $sep;
 if ( get_post_type() != 'post' ) {
 $post_type = get_post_type_object(get_post_type());
 $slug = $post_type->rewrite;
 printf($link, $home_link . '/' . $slug['slug'] . '/', $post_type->labels->singular_name);
 if ($show_current) echo $sep . $before . get_the_title() . $after;
 } else {
 $cat = get_the_category(); $cat = $cat[0];
 $cats = get_category_parents($cat, TRUE, $sep);
 if (!$show_current || get_query_var('cpage')) $cats = preg_replace("#^(.+)$sep$#", "$1", $cats);
 $cats = preg_replace('#<a([^>]+)>([^<]+)<\/a>#', $link_before . '<a$1' . $link_attr .'>' . $link_in_before . '$2' . $link_in_after .'</a>' . $link_after, $cats);
 echo $cats;
 if ( get_query_var('cpage') ) {
 echo $sep . sprintf($link, get_permalink(), get_the_title()) . $sep . $before . sprintf($text['cpage'], get_query_var('cpage')) . $after;
 } else {
 if ($show_current) echo $before . get_the_title() . $after;
 }
 }
 // custom post type
 } elseif ( !is_single() && !is_page() && get_post_type() != 'post' && !is_404() ) {
 $post_type = get_post_type_object(get_post_type());
 if ( get_query_var('paged') ) {
 echo $sep . sprintf($link, get_post_type_archive_link($post_type->name), $post_type->label) . $sep . $before . sprintf($text['page'], get_query_var('paged')) . $after;
 } else {
 if ($show_current) echo $sep . $before . $post_type->label . $after;
 }
 } elseif ( is_attachment() ) {
 if ($show_home_link) echo $sep;
 $parent = get_post($parent_id);
 $cat = get_the_category($parent->ID); $cat = $cat[0];
 if ($cat) {
 $cats = get_category_parents($cat, TRUE, $sep);
 $cats = preg_replace('#<a([^>]+)>([^<]+)<\/a>#', $link_before . '<a$1' . $link_attr .'>' . $link_in_before . '$2' . $link_in_after .'</a>' . $link_after, $cats);
 echo $cats;
 }
 printf($link, get_permalink($parent), $parent->post_title);
 if ($show_current) echo $sep . $before . get_the_title() . $after;
 } elseif ( is_page() && !$parent_id ) {
 if ($show_current) echo $sep . $before . get_the_title() . $after;
 } elseif ( is_page() && $parent_id ) {
 if ($show_home_link) echo $sep;
 if ($parent_id != $frontpage_id) {
 $breadcrumbs = array();
 while ($parent_id) {
 $page = get_page($parent_id);
 if ($parent_id != $frontpage_id) {
 $breadcrumbs[] = sprintf($link, get_permalink($page->ID), get_the_title($page->ID));
 }
 $parent_id = $page->post_parent;
 }
 $breadcrumbs = array_reverse($breadcrumbs);
 for ($i = 0; $i < count($breadcrumbs); $i++) {
 echo $breadcrumbs[$i];
 if ($i != count($breadcrumbs)-1) echo $sep;
 }
 }
 if ($show_current) echo $sep . $before . get_the_title() . $after;
 } elseif ( is_tag() ) {
 if ( get_query_var('paged') ) {
 $tag_id = get_queried_object_id();
 $tag = get_tag($tag_id);
 echo $sep . sprintf($link, get_tag_link($tag_id), $tag->name) . $sep . $before . sprintf($text['page'], get_query_var('paged')) . $after;
 } else {
 if ($show_current) echo $sep . $before . sprintf($text['tag'], single_tag_title('', false)) . $after;
 }
 } elseif ( is_author() ) {
 global $author;
 $author = get_userdata($author);
 if ( get_query_var('paged') ) {
 if ($show_home_link) echo $sep;
 echo sprintf($link, get_author_posts_url($author->ID), $author->display_name) . $sep . $before . sprintf($text['page'], get_query_var('paged')) . $after;
 } else {
 if ($show_home_link && $show_current) echo $sep;
 if ($show_current) echo $before . sprintf($text['author'], $author->display_name) . $after;
 }
 } elseif ( is_404() ) {
 if ($show_home_link && $show_current) echo $sep;
 if ($show_current) echo $before . $text['404'] . $after;
 } elseif ( has_post_format() && !is_singular() ) {
 if ($show_home_link) echo $sep;
 echo get_post_format_string( get_post_format() );
 }
 echo $wrap_after;
 }
}

然后在需要显示面包屑的地方加上以下代码：

<?php if (function_exists('MBThemes_breadcrumbs')) MBThemes_breadcrumbs(); ?>