Facebook如何知道要解析的文章？ [英] How Does Facebook Know What Image To Parse Out of An Article?

问题描述

首先，我想说，我不太确定哪里发布，但它是非常多的编程相关。如果这是错误的地方，我很抱歉，请让我知道我应该在哪里发布。

当在朋友墙上分享文章时，Facebook将抓住一个缩略图的文章。他们如何总是从文章中获得正确的缩略图？

它没有抓住 http://www.nytimes.com/2010/06/07/world/asia/07convoys.html?hp 为例，而是抓住正确的图像元素对应于文章。

我正在寻找类似的东西，并想知道一个很好的方法来解析html来找到给出这个例子的图像。谢谢。

解决方案

实际上，Facebook的缩略图查找方式并不那么神奇。它搜索一组< meta> 和< link> 标签，这些标签指定哪个标题，描述和要使用的图像。

如果找不到任何< meta> 和 < link> 标签，它基本上要求用户选择哪个< img> 标签适合。

在NY Times的情况下，它使用以下内容：

 < meta name =thumbnailcontent =whatever.jpg/> 
  

Facebook建议您使用< link> 标签代替缩略图。

 < meta name =titlecontent =title/> 
< meta name =descriptioncontent =description/> 
< link rel =image_srchref =thumbnail_image/> 
  

资料来源： Facebok分享/指定元标记

First off I want to say that I wasn't really sure where to post this but it is very much programming related. If it is in the wrong spot I apologize and please let me know where I should post it instead.

When sharing an article on a friends wall, facebook will grab a thumbnail of the article. How do they always get the right thumbnail from articles?

It doesn't grab the logo img element of of http://www.nytimes.com/2010/06/07/world/asia/07convoys.html?hp for example but rather grabs the correct image element that corresponds with the article.

I'm looking to do something similar and was wondering of a good way to parse the html to find the image given this example. Thanks.

解决方案

Actually, Facebook's way of finding thumbnails isn't so magical. It searches for a set of <meta> and <link> tags which specify which title, description, and image to use.

If it cannot find any of the <meta> and <link> tags it is looking for, it basically asks the user to choose whichever <img> tag fits.

In the case of the NY Times, it uses the following:

<meta name="thumbnail" content="whatever.jpg" />

Facebook recommends you use a <link> tag instead for the thumbnail.

<meta name="title" content="title" />
<meta name="description" content="description " />
<link rel="image_src" href="thumbnail_image" />

Source: Facebok Share/Specifying Meta Tags

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