从外部网站获取标题和元标记

Question

从外部网站获取标题和元标记

我想弄清楚如何获得

<title>A common title</title>
<meta name="keywords" content="Keywords blabla" />
<meta name="description" content="This is the description" />

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即使它以任何顺序排列,我也听说过PHP Simple HTML DOM Parser,但我真的不想使用它.除了使用PHP Simple HTML DOM Parser之外,是否可以使用解决方案.

preg_match 如果HTML无效,将无法执行此操作？

cURL可以用preg_match做这样的事吗？

Facebook做了类似这样的事情,但它通过使用正确使用:

<meta property="og:description" content="Description blabla" />

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我想要这样的东西,以便当有人发布链接时,它应该检索标题和元标记.如果没有元标记,那么它会被忽略或者用户可以自己设置(但我稍后会自己做).

Answer 1

sha*_*mar 155

这是应该的方式:

function file_get_contents_curl($url)
{
    $ch = curl_init();

    curl_setopt($ch, CURLOPT_HEADER, 0);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);

    $data = curl_exec($ch);
    curl_close($ch);

    return $data;
}

$html = file_get_contents_curl("http://example.com/");

//parsing begins here:
$doc = new DOMDocument();
@$doc->loadHTML($html);
$nodes = $doc->getElementsByTagName('title');

//get and display what you need:
$title = $nodes->item(0)->nodeValue;

$metas = $doc->getElementsByTagName('meta');

for ($i = 0; $i < $metas->length; $i++)
{
    $meta = $metas->item($i);
    if($meta->getAttribute('name') == 'description')
        $description = $meta->getAttribute('content');
    if($meta->getAttribute('name') == 'keywords')
        $keywords = $meta->getAttribute('content');
}

echo "Title: $title". '<br/><br/>';
echo "Description: $description". '<br/><br/>';
echo "Keywords: $keywords";

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这不适用于所有网站.例如:http://www.baidu.com (4认同)
两年后,仍然可以完美地工作,更改属性以获得与OpenGraph相关的`og:`标签,并且运行良好 (3认同)
效果很好，但在我的情况下，它对少数 URL 不起作用，调试后我发现，`$nodes = $doc->getElementsByTagName('title');` 返回结果的长度，每当标题丢失时，它都会发出警告。所以只需将下一行即`$title = $nodes->item(0)->nodeValue;`替换为`if ($nodes->length>0) { $title = $nodes->item(0)->nodeValue ; }` (2认同)

Answer 2

Bob*_*eey 35

<?php
// Assuming the above tags are at www.example.com
$tags = get_meta_tags('http://www.example.com/');

// Notice how the keys are all lowercase now, and
// how . was replaced by _ in the key.
echo $tags['author'];       // name
echo $tags['keywords'];     // php documentation
echo $tags['description'];  // a php manual
echo $tags['geo_position']; // 49.33;-86.59
?>

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但这并不提供页面标题 (3认同)
^因为它是一个与元标记相关的函数，它究竟会如何返回一些东西——它不关心。 (2认同)
OP要求。 (2认同)

Answer 3

Llo*_*ore 8

get_meta_tags将帮助你除了标题之外的所有人.要获得标题只需使用正则表达式.

$url = 'http://some.url.com';
preg_match("/<title>(.+)<\/title>/siU", file_get_contents($url), $matches);
$title = $matches[1];

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希望有所帮助.

Answer 4

小智 7

get_meta_tags 没有与标题一起工作。

只有具有名称属性的元标记，例如

<meta name="description" content="the description">

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将被解析。

Answer 5

Add*_*ons 6

Php的本机函数:get_meta_tags()

http://php.net/manual/en/function.get-meta-tags.php

Answer 6

okn*_*ate 5

不幸的是，内置的 php 函数 get_meta_tags() 需要 name 参数，而某些站点（例如 twitter）为了支持 property 属性而将其保留。此函数混合使用正则表达式和 dom 文档，将从网页中返回元标记的键控数组。它检查名称参数，然后检查属性参数。这已经在 instragram、pinterest 和 twitter 上进行了测试。

/**
 * Extract metatags from a webpage
 */
function extract_tags_from_url($url) {
  $tags = array();

  $ch = curl_init();
  curl_setopt($ch, CURLOPT_HEADER, 0);
  curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
  curl_setopt($ch, CURLOPT_URL, $url);
  curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);

  $contents = curl_exec($ch);
  curl_close($ch);

  if (empty($contents)) {
    return $tags;
  }

  if (preg_match_all('/<meta([^>]+)content="([^>]+)>/', $contents, $matches)) {
    $doc = new DOMDocument();
    $doc->loadHTML('<?xml encoding="utf-8" ?>' . implode($matches[0]));
    $tags = array();
    foreach($doc->getElementsByTagName('meta') as $metaTag) {
      if($metaTag->getAttribute('name') != "") {
        $tags[$metaTag->getAttribute('name')] = $metaTag->getAttribute('content');
      }
      elseif ($metaTag->getAttribute('property') != "") {
        $tags[$metaTag->getAttribute('property')] = $metaTag->getAttribute('content');
      }
    }
  }

  return $tags;
}

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Answer 7

cro*_*lee 5

我们不应该使用OG吗？

选择的答案很好，但在网站重定向时不起作用（非常常见！），并且不返回OG 标签，这是新的行业标准。这是一个在 2018 年更有用的小功能。它尝试获取 OG 标签，如果无法获取，则回退到元标签：

function getSiteOG( $url, $specificTags=0 ){
    $doc = new DOMDocument();
    @$doc->loadHTML(file_get_contents($url));
    $res['title'] = $doc->getElementsByTagName('title')->item(0)->nodeValue;

    foreach ($doc->getElementsByTagName('meta') as $m){
        $tag = $m->getAttribute('name') ?: $m->getAttribute('property');
        if(in_array($tag,['description','keywords']) || strpos($tag,'og:')===0) $res[str_replace('og:','',$tag)] = $m->getAttribute('content');
    }
    return $specificTags? array_intersect_key( $res, array_flip($specificTags) ) : $res;
}

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如何使用它：

/////////////
//SAMPLE USAGE:
print_r(getSiteOG("http://www.stackoverflow.com")); //note the incorrect url

/////////////
//OUTPUT:
Array
(
    [title] => Stack Overflow - Where Developers Learn, Share, & Build Careers
    [description] => Stack Overflow is the largest, most trusted online community for developers to learn, shareâ âtheir programming âknowledge, and build their careers.
    [type] => website
    [url] => https://stackoverflow.com/
    [site_name] => Stack Overflow
    [image] => https://cdn.sstatic.net/Sites/stackoverflow/img/apple-touch-icon@2.png?v=73d79a89bded
)

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Answer 8

SNS*_*que 5

一个简单的函数来了解如何检索 og:tags、标题和描述，请自行调整

function read_og_tags_as_json($url){


    $ch = curl_init();

    curl_setopt($ch, CURLOPT_HEADER, 0);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);

    $HTML_DOCUMENT = curl_exec($ch);
    curl_close($ch);

    $doc = new DOMDocument();
    $doc->loadHTML($HTML_DOCUMENT);

    // fecth <title>
    $res['title'] = $doc->getElementsByTagName('title')->item(0)->nodeValue;

    // fetch og:tags
    foreach( $doc->getElementsByTagName('meta') as $m ){

          // if had property
          if( $m->getAttribute('property') ){

              $prop = $m->getAttribute('property');

              // here search only og:tags
              if( preg_match("/og:/i", $prop) ){

                  // get results on an array -> nice for templating
                  $res['og_tags'][] =
                  array( 'property' => $m->getAttribute('property'),
                          'content' => $m->getAttribute('content') );
              }

          }
          // end if had property

          // fetch <meta name="description" ... >
          if( $m->getAttribute('name') == 'description' ){

            $res['description'] = $m->getAttribute('content');

          }


    }
    // end foreach

    // render JSON
    echo json_encode($res, JSON_PRETTY_PRINT |
    JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);

}

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返回此页面（可能有更多信息）：

{
    "title": "php - Getting title and meta tags from external website - Stack Overflow",
    "og_tags": [
        {
            "property": "og:type",
            "content": "website"
        },
        {
            "property": "og:url",
            "content": "/sf/ask/259795021/"
        },
        {
            "property": "og:site_name",
            "content": "Stack Overflow"
        },
        {
            "property": "og:image",
            "content": "https://cdn.sstatic.net/Sites/stackoverflow/Img/apple-touch-icon@2.png?v=73d79a89bded"
        },
        {
            "property": "og:title",
            "content": "Getting title and meta tags from external website"
        },
        {
            "property": "og:description",
            "content": "I want to try figure out how to get the\n\n&lt;title&gt;A common title&lt;/title&gt;\n&lt;meta name=\"keywords\" content=\"Keywords blabla\" /&gt;\n&lt;meta name=\"description\" content=\"This is the descript..."
        }
    ]
}

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