wordpress自动给文章的外部链接添加nofollow属性

add_filter('the_content','web589_the_content_nofollow',999);
function web589_the_content_nofollow($content){
 preg_match_all('/href="(.*?)"/',$content,$matches);
 if($matches){
  foreach($matches[1] as $val){
   if( strpos($val,home_url())===false ) $content=str_replace("href="$val"", "href="$val" rel="external nofollow" ",$content);
  }
 }
 return $content;
}

add_filter('wp_tag_cloud','web589_tag_cloud_nofollow');
function web589_tag_cloud_nofollow($cloud){
 $cloud=preg_replace('/  return $cloud;
}

add_filter('get_comment_author_link','web589_comment_author_link');
function web589_comment_author_link($link){
  $args=array('//','//');
 $link=preg_replace($args,'',$link);
 return $link;
}