WordPress关键词自动内链代码方法

WordPress文章关键词自动内链到相关标签页，提高网站的SEO，增加用户粘性

将以下代码添加到functions.php文件倒数第二行。

//WordPress文字标签关键词自动内链
$match_num_from = 1;		//一篇文章中同一個標籤少於幾次不自動鏈接
$match_num_to = 4;		//一篇文章中同一個標籤最多自動鏈接幾次
function tag_sort($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($cleankeyword, '$'),__('查看更多关于 %s 的文章'))."\"";
				$url .= ' target="_blank"';
				$url .= ">".addcslashes($cleankeyword, '$')."</a>";
				$limit = rand($match_num_from,$match_num_to);
				$content = preg_replace( '|(<a[^>]+>)(.*)<pre.*?>('.$ex_word.')(.*)<\/pre>(</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);