Java xPath-从XML提取子文档 [英] Java xPath - extract subdocument from XML

问题描述

我有一个XML文档，如下所示:

I have an XML document as follows:

<DocumentWrapper>
  <DocumentHeader>
    ...
  </DocumentHeader>
  <DocumentBody>
    <Invoice>
      <Buyer/>
      <Seller/>
    </Invoice>
   </DocumentBody>
 </DocumentWrapper>

我想从其中提取DocumentBody元素的内容作为String(原始XML文档):

I would like to extract from it the content of DocumentBody element as String, raw XML document:

<Invoice>
  <Buyer/>
  <Seller/>
</Invoice>

使用xPath可能很容易获得:

With xPath it could be simple to get by:

/DocumentWrapper/DocumentBody

毫无疑问，我的Java代码不想按我希望的那样工作.它返回空行而不是预期的结果.有没有机会这样做，还是我必须返回NodeList然后从它们中生成xml文档?

Unfrotunatelly, my Java code doesn't want to work as I want. It returns empty lines instead of expected result. Is there any chance to do that, or I have to return NodeList and then genereate xml document from them?

我的Java代码:

XPathFactory xPathFactoryXPathFactory.newInstance();
XPath xPath xPathFactory.newXPath();
XPathExpression xPath.compile(xPathQuery);

String result = expression.evaluate(xmlDocument);

推荐答案

调用此方法

String result = expression.evaluate(xmlDocument);

与调用它相同

String result = (String) expression.evaluate(xmlDocument, XPathConstants.STRING);

返回结果节点的字符数据，或者如果结果节点是元素，则返回所有子节点的字符数据.

which returns the character data of the result node, or the character data of all child nodes in case the result node is an element.

您可能应该执行以下操作:

You should probably do something like this:

Node result = (Node) expression.evaluate(xmlDocument, XPathConstants.NODE);
TransformerFactory.newInstance().newTransformer()
            .transform(new DOMSource(result), new StreamResult(System.out));

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