php-无法选择带有xpath的元素

我必须在这里丢失一些东西,但是我无法弄清楚.

我正在使用SimpleXML来解析RSS和ATOM提要,但是问题是,使用相同的xpath方法,我无法选择< link>从ATOM提要与RSS提要一起使用时.

两种饲料的样品

<?xml version="1.0" encoding="UTF-8"?>
<RSS version="2.0"
    xmlns:content="http://purl.org/RSS/1.0/modules/content/"
    xmlns:wfw="http://wellformedweb.org/CommentAPI/"
    xmlns:dc="http://purl.org/dc/elements/1.1/"
    xmlns:atom="http://www.w3.org/2005/Atom"
    xmlns:sy="http://purl.org/RSS/1.0/modules/syndication/"
    xmlns:slash="http://purl.org/RSS/1.0/modules/slash/"
    >

<channel>
    <title>比特客栈的文艺复兴</title>
    <atom:link href="http://bitinn.net/Feed/" rel="self" type="application/RSS+xml" />
    <link>http://bitinn.net</link>
    <description>We don&#039;t choose who we are, but we do choose who we become.</description>
    <lastBuildDate>Sun, 27 Apr 2014 14:43:22 +0000</lastBuildDate>
    <language>en-US</language>
        <sy:updatePeriod>hourly</sy:updatePeriod>
...


<?xml version="1.0" encoding="UTF-8"?>
<Feed 
    xmlns="http://www.w3.org/2005/Atom" 
    xmlns:thr="http://purl.org/syndication/thread/1.0" xml:lang="en-US" xml:base="http://bitinn.net/wp-atom.PHP">
    <title type="text">比特客栈的文艺复兴</title>
    <subtitle type="text">We don't choose who we are, but we do choose who we become.</subtitle>
    <updated>2014-04-27T14:43:22Z</updated>
    <link rel="alternate" type="text/html" href="http://bitinn.net"/>
    <id>http://bitinn.net/Feed/atom/</id>
    <link rel="self" type="application/atom+xml" href="http://bitinn.net/Feed/atom/"/>
    <generator uri="http://wordpress.org/" version="3.9">wordpress</generator>
    <link rel="hub" href="http://pubsubhubbub.appspot.com"/>
    <link rel="hub" href="http://superfeedr.com/hubbub"/>
    <entry>
        <author>
            <name>店长</name>
            <uri>http://bitinn.net/</uri>
        </author>
...

似乎$xml-> channel-> xpath(‘atom：link [@ rel =“ self”]’);适用于RSS Feed,但$xml-> xpath(‘link [@ rel =“ self”]’);不适用于ATOM供稿.我怀疑我在第二个查询中弄乱了名称空间,但没有找到正确的xpath查询.

有人有主意吗？

解决方法:

在第二种情况下,在提要根元素viz上设置了默认的xmlns.

<Feed xmlns="http://www.w3.org/2005/Atom"  ...

意味着Feed和嵌套元素现在位于http://www.w3.org/2005/Atom中.您将需要调整xpath来适应这一点.

xpath将是

atom:Feed/atom:link[@rel="self"]

其中xmlns：atom =’http://www.w3.org/2005/Atom’