如何從使用XPath/XQuery的

Question

這裏RSS源獲取圖片的URL是RSS提要的一個例子：

<item> 
<title>Stem cells being made from blood</title> 
<description>A patient's own blood has been used to make personalised stem cells, which doctors hope can be used to treat a range of diseases.</description> 
<link>http://www.bbc.co.uk/news/health-20539835#sa-ns_mchannel=rss&ns_source=PublicRSS20-sa</link> 
<guid isPermaLink="false">http://www.bbc.co.uk/news/health-20539835</guid> 
<pubDate>Fri, 30 Nov 2012 00:45:53 GMT</pubDate> 
<media:thumbnail xmlns:media="http://search.yahoo.com/mrss/" width="66" height="49" url="http://news.bbcimg.co.uk/media/images/64469000/jpg/_64469170_c0147104-red_blood_cells%2C_artwork-spl.jpg"/> 
<media:thumbnail xmlns:media="http://search.yahoo.com/mrss/" width="144" height="81" url="http://news.bbcimg.co.uk/media/images/64469000/jpg/_64469171_c0147104-red_blood_cells%2C_artwork-spl.jpg"/> 

我需要媒體來獲取.JPG圖片的URL：縮略圖.. 我該怎麼辦那與xpath或xquery？ 任何人都可以幫助我嗎？ 謝謝！

Answer 1

假設你的XML是：

<item> 
    <title>Stem cells being made from blood</title> 
    <description>A patient's own blood has been used to make personalised stem cells, which doctors hope can be used to treat a range of diseases.</description> 
    <link>http://www.bbc.co.uk/news/health-20539835#sa-ns_mchannel=rss&amp;ns_source=PublicRSS20-sa</link> 
    <guid isPermaLink="false">http://www.bbc.co.uk/news/health-20539835</guid> 
    <pubDate>Fri, 30 Nov 2012 00:45:53 GMT</pubDate> 
    <media:thumbnail xmlns:media="http://search.yahoo.com/mrss/" width="66" height="49" url="http://news.bbcimg.co.uk/media/images/64469000/jpg/_64469170_c0147104-red_blood_cells%2C_artwork-spl.jpg"/> 
    <media:thumbnail xmlns:media="http://search.yahoo.com/mrss/" width="144" height="81" url="http://news.bbcimg.co.uk/media/images/64469000/jpg/_64469171_c0147104-red_blood_cells%2C_artwork-spl.jpg"/> 
</item> 

的XPath //item/media:thumbnail/@url選擇你想要的節點。在這種情況下，您需要在XPath引擎中傳遞名稱空間和前綴。
或者，您可以使用此XPath：

//item/*[local-name() = 'thumbnail' 
    and namespace-uri() = 'http://search.yahoo.com/mrss/']/@url