php - 将目标_blank添加到外部链接-Parsedown PHP

我使用Parsedown将html从数据库解析到我的站点。使用parsedown，您不能真正将target="_blank"添加到链接中。
所以我要做的是将target="_blank"添加到外部链接。我在parsedown.php中找到了这个函数：

protected function inlineLink($Excerpt)
{
    $Element = array(
        'name' => 'a',
        'handler' => 'line',
        'text' => null,
        'attributes' => array(
            'href' => null,
            'title' => null,
        ),
    );

    $extent = 0;

    $remainder = $Excerpt['text'];

    if (preg_match('/\[((?:[^][]++|(?R))*+)\]/', $remainder, $matches))
    {
        $Element['text'] = $matches[1];

        $extent += strlen($matches[0]);

        $remainder = substr($remainder, $extent);
    }
    else
    {
        return;
    }

    if (preg_match('/^[(]\s*+((?:[^ ()]++|[(][^ )]+[)])++)(?:[ ]+("[^"]*"|\'[^\']*\'))?\s*[)]/', $remainder, $matches))
    {
        $Element['attributes']['href'] = $matches[1];

        if (isset($matches[2]))
        {
            $Element['attributes']['title'] = substr($matches[2], 1, - 1);
        }

        $extent += strlen($matches[0]);
    }
    else
    {
        if (preg_match('/^\s*\[(.*?)\]/', $remainder, $matches))
        {
            $definition = strlen($matches[1]) ? $matches[1] : $Element['text'];
            $definition = strtolower($definition);

            $extent += strlen($matches[0]);
        }
        else
        {
            $definition = strtolower($Element['text']);
        }

        if ( ! isset($this->DefinitionData['Reference'][$definition]))
        {
            return;
        }

        $Definition = $this->DefinitionData['Reference'][$definition];

        $Element['attributes']['href'] = $Definition['url'];
        $Element['attributes']['title'] = $Definition['title'];
    }

    $Element['attributes']['href'] = str_replace(array('&', '<'), array('&amp;', '&lt;'), $Element['attributes']['href']);

    return array(
        'extent' => $extent,
        'element' => $Element,
    );
}

现在，我尝试的是这个（添加了对我所做更改的评论）：

protected function inlineLink($Excerpt)
{
    $Element = array(
        'name' => 'a',
        'handler' => 'line',
        'text' => null,
        'attributes' => array(
            'href' => null,
            'target' => null, // added this
            'title' => null,
        ),
    );

    $extent = 0;

    $remainder = $Excerpt['text'];

    if (preg_match('/\[((?:[^][]++|(?R))*+)\]/', $remainder, $matches))
    {
        $Element['text'] = $matches[1];

        $extent += strlen($matches[0]);

        $remainder = substr($remainder, $extent);
    }
    else
    {
        return;
    }

    if (preg_match('/^[(]\s*+((?:[^ ()]++|[(][^ )]+[)])++)(?:[ ]+("[^"]*"|\'[^\']*\'))?\s*[)]/', $remainder, $matches))
    {
        $Element['attributes']['href'] = $matches[1];

        if (isset($matches[2]))
        {
            $Element['attributes']['title'] = substr($matches[2], 1, - 1);
        }

        $extent += strlen($matches[0]);
    }
    else
    {
        if (preg_match('/^\s*\[(.*?)\]/', $remainder, $matches))
        {
            $definition = strlen($matches[1]) ? $matches[1] : $Element['text'];
            $definition = strtolower($definition);

            $extent += strlen($matches[0]);
        }
        else
        {
            $definition = strtolower($Element['text']);
        }

        if ( ! isset($this->DefinitionData['Reference'][$definition]))
        {
            return;
        }

        $Definition = $this->DefinitionData['Reference'][$definition];

        $Element['attributes']['href'] = $Definition['url'];
        if (strpos($Definition['url'], 'example.com') !== false) { // added this aswell, checking if its our own URL
            $Element['attributes']['target'] = '_blank';
        }
        $Element['attributes']['title'] = $Definition['title'];
    }

    $Element['attributes']['href'] = str_replace(array('&', '<'), array('&amp;', '&lt;'), $Element['attributes']['href']);

    return array(
        'extent' => $extent,
        'element' => $Element,
    );
}

有什么建议可以做到这一点吗？

最佳答案

github上的此类问题already exists。请参阅this评论。
我的分机可以自动设置rel=“nofollow”和target=“\u blank”
当检测到链接为外部链接时，该链接的属性。你可以
也可以通过属性块手动设置这些属性：

[text](http://example.com) {rel="nofollow" target="_blank"}

Automatic rel="nofollow" Attribute on External Links

// custom external link attributes
$parser->links_external_attr = array(
    'rel' => 'nofollow',
    'target' => '_blank'
);

如果要在parsedown类中进行更改而不使用parsedown额外的插件扩展，可以执行以下操作：
1）在\Parsedown::element方法中，在the first line$markup = '<'.$Element['name'];之后添加此行$Element = $this->additionalProcessElement($Element);
2）在Parsedown类中添加新方法：

protected function additionalProcessElement($Element) { }

3）扩展parsedown类并保存为myparsedown.php文件：

<?php
namespace myapps;

require_once __DIR__.'/Parsedown.php';

/**
 * Class MyParsedown
 * @package app
 */
class MyParsedown extends \Parsedown
{
    /**
     * @param array $Element
     * @return array
     */
    protected function additionalProcessElement($Element)
    {
        if ($Element['name'] == 'a' && $this->isExternalUrl($Element['attributes']['href'])) {
            $Element['attributes']['target'] = '_blank';
        }

        return $Element;
    }

    /**
     * Modification of the funciton from answer to the question "How To Check Whether A URL Is External URL or Internal URL With PHP?"
     * @param string $url
     * @param null $internalHostName
     * @see https://stackoverflow.com/a/22964930/7663972
     * @return bool
     */
    protected function isExternalUrl($url, $internalHostName = null) {
        $components = parse_url($url);
        $internalHostName = ($internalHostName == null) ? $_SERVER['HTTP_HOST'] : $internalHostName;
        // we will treat url like '/relative.php' as relative
        if (empty($components['host'])) {
            return false;
        }
        // url host looks exactly like the local host
        if (strcasecmp($components['host'], $internalHostName) === 0) {
            return false;
        }

        $isNotSubdomain = strrpos(strtolower($components['host']), '.'.$internalHostName) !== strlen($components['host']) - strlen('.'.$internalHostName);

        return $isNotSubdomain;
    }
}

4）创建test.php文件并运行它：

require_once __DIR__.'/MyParsedown.php';

$parsedown = new \myapps\MyParsedown();
$text = 'External link to [example.com](http://example.com/abc)';
echo $parsedown->text($text);

此HTML代码将显示在浏览器页面上（当然，如果您的主机不是example.com）：
<p>External link to <a href="http://example.com/abc" target="_blank">example.com</a></p>