WordPress文章标签（tag）自动添加内链

在functions.php文件添加如下代码：

方法一

//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;
 }

方法二

/* 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($cleankeyword, '$'),__('【查看含有[%s]标签的文章】'))."\"";
                $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 */

方法三

/**
 * WordPress 自动为文章标签添加该标签的链接
 * https://www.josejang.com/about-work/110.html
 */
function wpkj_auto_add_tag_link($content){

    $limit = 1; // 设置同一个标签添加几次链接

    $posttags = get_the_tags();

    if ($posttags) {
        foreach($posttags as $tag) {
            $link = get_tag_link($tag->term_id);
            $keyword = $tag->name;

            $cleankeyword = stripslashes($keyword);
            $url = '<a target="_blank" href="'.$link.'" title="'.str_replace('%s', addcslashes($cleankeyword, '$'), __('View all posts in %s')).'">'.addcslashes($cleankeyword, '$').'</a>';
            $regEx = '\'(?!((<.*?)|(<a.*?)))('. $cleankeyword . ')(?!(([^<>]*?)>)|([^>]*?</a>))\'s';
            $content = preg_replace($regEx,$url,$content,$limit);
        }
    }

    return $content;
}
add_filter( 'the_content', 'wpkj_auto_add_tag_link', 1 );

方法四

/* 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($cleankeyword, '$'),__('【查看含有[%s]标签的文章】'))."\"";
                $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 */