如何使用XPath使用Java中的命名空间查询XML？ [英] How to query XML using namespaces in Java with XPath?

问题描述

当我的XML看起来像这样（没有 xmlns ）时，我可以轻松地使用XPath查询它，如 / workbook / sheets / sheet [1]

When my XML looks like this (no xmlns) then I can easly query it with XPath like /workbook/sheets/sheet[1]

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<workbook>
  <sheets>
    <sheet name="Sheet1" sheetId="1" r:id="rId1"/>
  </sheets>
</workbook>

但是看起来像这样我就不能

But when it looks like this then I can't

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<workbook xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main" xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships">
  <sheets>
    <sheet name="Sheet1" sheetId="1" r:id="rId1"/>
  </sheets>
</workbook>

任何想法？

推荐答案

在第二个示例XML文件中，元素绑定到命名空间。您的XPath正在尝试处理绑定到默认无命名空间命名空间的元素，因此它们不匹配。

In the second example XML file the elements are bound to a namespace. Your XPath is attempting to address elements that are bound to the default "no namespace" namespace, so they don't match.

首选方法是注册命名空间名称空间前缀。它使您的XPath更容易开发，读取和维护。

The preferred method is to register the namespace with a namespace-prefix. It makes your XPath much easier to develop, read, and maintain.

但是，注册命名空间并使用namespace-prefix不是必需的。您的XPath。

您可以制定一个XPath表达式，该表达式使用元素的通用匹配和限制匹配所需的 local-name（）和 namespace-uri（）。例如：

You can formulate an XPath expression that uses a generic match for an element and a predicate filter that restricts the match for the desired local-name() and the namespace-uri(). For example:

/*[local-name()='workbook'
    and namespace-uri()='http://schemas.openxmlformats.org/spreadsheetml/2006/main']
  /*[local-name()='sheets'
      and namespace-uri()='http://schemas.openxmlformats.org/spreadsheetml/2006/main']
  /*[local-name()='sheet'
      and namespace-uri()='http://schemas.openxmlformats.org/spreadsheetml/2006/main'][1]

如你所见，它产生了极长的时间和详细的XPath语句非常难以阅读（和维护）。

As you can see, it produces an extremely long and verbose XPath statement that is very difficult to read (and maintain).

您也可以匹配 local-name（）的元素并忽略命名空间。例如：

You could also just match on the local-name() of the element and ignore the namespace. For example:

/*[local-name()='workbook']/*[local-name()='sheets']/*[local-name()='sheet'][1]

但是，您冒着匹配错误元素的风险。如果您的XML具有混合词汇表（对于此实例可能不是问题），则使用相同的 local-name（），您的XPath可以匹配错误的元素并选择错误的内容：

However, you run the risk of matching the wrong elements. If your XML has mixed vocabularies (which may not be an issue for this instance) that use the same local-name(), your XPath could match on the wrong elements and select the wrong content:

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