免插件WordPress实现文章自动提取tag并添加链接

WordPress里要实现文章自动提取tag方法有很多，最方便的使用插件。今天分享一个不用插件来实现文章的自动提取tag并添加链接的方法。

登录博客后台，打开博客主题的function.php功能函数，在这个文件里面添加如下代码：

//连接数量
$match_num_from = 1;  //一个关键字少于多少不替换
$match_num_to = 10; //一个关键字最多替换
//连接到WordPress的模块
add_filter('the_content','tag_link',1);
//按长度排序
function tag_sort($a, $b){
	if ( $a->name == $b->name ) return 0;
	return ( strlen($a->name) > strlen($b->name) ) ? -1 : 1;
}
//改变标签关键字
function tag_link($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;
			 //连接代码
			 $cleankeyword = stripslashes($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);

			//不连接的 代码
                         $content = preg_replace( '|(<a[^>]+>)(.*)('.$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;
}