当根标记获得 xmlns 属性时，XPath 无法正常工作
我正在尝试使用 XPath 解析 xml 文件，
DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
domFactory.setNamespaceAware(true); // never forget this!
DocumentBuilder builder = domFactory.newDocumentBuilder();
Document doc = builder.parse(File);
XPathFactory factory = XPathFactory.newInstance();
XPath xpath = factory.newXPath();
XPathExpression expr
= xpath.compile("//PerosnList/List/Person");
我花了很多时间才发现它不起作用，因为根元素具有 xmlns 属性 一旦我删除了 attr，它就可以正常工作了！，我如何解决这个 xlmns attr 而不从文件中删除它？
xml 看起来像这样：
<?xml version="1.0" encoding="utf-8"?>
<Root xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.datacontract.org/2004/07/vsDal.Entities">
.....
....
<PersonList>
...
<List>
<Person></Person>
<Person></Person>
<Person></Person>
</List>
</PersonList>
</Root>
谢谢。
I'm trying to parse an xml file using XPath
DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
domFactory.setNamespaceAware(true); // never forget this!
DocumentBuilder builder = domFactory.newDocumentBuilder();
Document doc = builder.parse(File);
XPathFactory factory = XPathFactory.newInstance();
XPath xpath = factory.newXPath();
XPathExpression expr
= xpath.compile("//PerosnList/List/Person");
It took me alot of time to see that it's not working cause the root element got xmlns attribute
once i remove the attr it works fine!, how can i workaround this xlmns attr without deleting it from the file ?
The xml looks like this:
<?xml version="1.0" encoding="utf-8"?>
<Root xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.datacontract.org/2004/07/vsDal.Entities">
.....
....
<PersonList>
...
<List>
<Person></Person>
<Person></Person>
<Person></Person>
</List>
</PersonList>
</Root>
Thanks.
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xmlns属性不仅仅是一个常规属性。它是一个 命名空间属性，用于唯一限定元素和属性。PersonList、List和Person元素“继承”该命名空间。您的 XPath 不匹配，因为您正在选择“无命名空间”中的元素。为了寻址绑定到 XPath 1.0 中的命名空间的元素，您必须定义命名空间前缀并在 XPath 表达式中使用它。您可以使 XPath 更加通用，只匹配
local-name，这样它就可以匹配元素，而不管其命名空间如何：The
xmlnsattribute is more than just a regular attribute. It is a namespace attribute which are used to uniquely qualify elements and attributes.The
PersonList,List, andPersonelements "inherit" that namespace. Your XPath isn't matching because you are selecting elements in the "no namespace". In order to address elements bound to a namespace in XPath 1.0 you must define a namespace-prefix and use it in your XPath expression.You could make your XPath more generic and just match on the
local-name, so that it matches the elements regardless of their namespace:您需要提供
NamespaceContext和您的表达式的命名空间。有关示例，请参阅此处。You need to provide a
NamespaceContextand namespace your expression. See here for an example.