WordPress文章关键词自动添加链接

/*
*自动为文章内的标签添加内链开始
*/
//连接数量
	$match_num_from = 1; //一个关键字少于多少不替换
	$match_num_to = 1; //一个关键字最多替换次数
	//连接到wordpress的模块
	add_filter('the_content','tag_link',1);
	//按长度排序
	function tag_sort($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($cleankeyword, '$'),__('查看所有文章关于 %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;	
	}