WordPress无插件实现文章关键词自动内链（含标签内链）

/* 自动为文章内的标签添加内链开始 */
$match_num_from = 1; //一篇文章中同一个标签少于几次不自动链接
$match_num_to = 1; //一篇文章中同一个标签最多自动链接几次
function tag_sort($a, $b){
if ( $a->name == $b->name ) return 0;
return ( strlen($a->name) > strlen($b->name) ) ? -1 : 1;
}
function tag_link($content){
global $match_num_from,$match_num_to;
$posttags = get_the_tags();
if ($posttags) {
usort($posttags, "tag_sort");
foreach($posttags as $tag) {
$link = get_tag_link($tag->term_id);
$keyword = $tag->name;
$cleankeyword = stripslashes($keyword);
$url = "<a href=\"$link\" title=\"".str_replace('%s',addcslashes($cleankeyword, '$'),__('View all posts in %s'))."\"";
$url .= ' target="_blank"';
$url .= ">".addcslashes($cleankeyword, '$')."</a>";
$limit = rand($match_num_from,$match_num_to);
$content = preg_replace( '|(<a[^>]+>)(.*)('.$ex_word.')(.*)(</a[^>]*>)|U'.$case, '$1$2%&&&&&%$4$5', $content);
$content = preg_replace( '|(<img)(.*?)('.$ex_word.')(.*?)(>)|U'.$case, '$1$2%&&&&&%$4$5', $content);
$cleankeyword = preg_quote($cleankeyword,'\'');
$regEx = '\'(?!((<.*?)|(<a.*?)))('. $cleankeyword . ')(?!(([^<>]*?)>)|([^>]*?</a>))\'s' . $case;
$content = preg_replace($regEx,$url,$content,$limit);
$content = str_replace( '%&&&&&%', stripslashes($ex_word), $content);
}
}
return $content;
}
add_filter('the_content','tag_link',1);
/* 自动为文章内的标签添加内链结束 *

/* 文章指定关键词添加内链开始 */
function replace_text_wps($text){
$replace = array(
'元素领域' => '<a href="http://www.yudouyudou.com/" target="_blank" title="元素领域">元素领域</a>',
'元素领域博客' => '<a href="http://m.yudouyudou.com/" target="_blank" title="元素领域博客">元素领域博客</a>',
'教程' => '<a href="http://www.yudouyudou.com/jiaochengheji/" target="_blank" title="教程">教程</a>'
);
$text = str_replace(array_keys($replace), $replace, $text);
return $text;
}

add_filter('the_content', 'replace_text_wps');