Question

我正在使用XPath提取URL128 XML元素的值。即使我在下面的例子中只有一个，也可以有很多。当我在SearchResponse元素上包含xmlns ='http：//c1.net.corbis.com/'时，我得到一个空的NodeList，但是当我删除该名称空间元素时，它工作正常。有没有我错过的配置？

String xmlData = "<SearchResponse xmlns='http://c1.net.corbis.com/'><searchResultDataXML><SearchResultData><SearchRequestUID Scope='Public' Type='Guid' Value='{cded773c-c4b7-4dd8-aaee-8e5b8b7a2475}'/><StartPosition Scope='Public' Type='Long' Value='1'/><EndPosition Scope='Public' Type='Long' Value='50'/><TotalHits Scope='Public' Type='Long' Value='323636'/></SearchResultData></searchResultDataXML><imagesXML><Images><Image><ImageUID Scope='Public' Type='Guid' Value='{a6f6d3e2-2c3f-4502-9741-eae2e1bb573a}'/><CorbisID Scope='Public' Type='String' Value='42-25763849'/><Title Scope='Public' Type='String' Value='Animals figurines'/><CreditLine Scope='Public' Type='String' Value='© Ocean/Corbis'/><IsRoyaltyFree Scope='Public' Type='Boolean' Value='True'/><AspectRatio Scope='Public' Type='String' Value='0.666667'/><URL128 Scope='Public' Type='String' Value='http://cachens.corbis.com/CorbisImage/thumb/25/76/38/25763849/42-25763849.jpg'/></Image></Images></imagesXML></SearchResponse>"; 
      InputSource source = new InputSource(new StringReader(xmlData)); 

      XPath xPath = XPathFactory.newInstance().newXPath(); 
      NodeList list = null; 
      try { 
       list = (NodeList) xPath.evaluate("//URL128/@Value", source, XPathConstants.NODESET); 
      } catch (Exception ex) { 
       System.out.println(ex.getMessage()); 
      } 
      for (int i = 0; i < list.getLength(); i++) { 
       System.out.println(list.item(i).getTextContent()); 
      } 

Answer 1

好，长话短说，你需要提供一个NamespaceContext您XPath：

final XPath xPath = XPathFactory.newInstance().newXPath(); 
xPath.setNamespaceContext(new NamespaceContext() { 
    @Override 
    public Iterator<String> getPrefixes(final String namespaceURI) { 
     return null; 
    } 
    @Override 
    public String getPrefix(final String namespaceURI) { 
     return null; 
    } 
    @Override 
    public String getNamespaceURI(final String prefix) { 
     return "http://c1.net.corbis.com/"; 
    } 
}); 
final NodeList list = (NodeList) xPath.evaluate("//c:URL128/@Value", source, XPathConstants.NODESET); 
for (int i = 0; i < list.getLength(); i++) { 
    System.out.println(list.item(i).getTextContent()); 
} 

这似乎是唯一的方法XPath需要我们实现在这种情况下是getNamespaceURI(String prefix)。

请注意，在这种情况下，“c：URL128”中的实际前缀并不重要 - 您可以轻松使用“：URL128”。当你的在你的XML中有多个命名空间时，区分它们变得很重要（如果元素相对较少，则使用Map或一系列if-then-else）。

如果您不能或不想硬代码，你可以自己从XML文档中提取出来，但需要多一点的代码前缀...

也this blog post详情请见。下面

Answer 2

是实现的两种方式是什么AlistairIsreal概述：

如果使用Spring，你可以依靠org.springframework.util.xml.SimpleNamespaceContext接口。

InputSource source = new InputSource(new StringReader(unescaped)); 

      XPath xPath = XPathFactory.newInstance().newXPath(); 
      NodeList list = null; 
      try 
      { 
       SimpleNamespaceContext nsCtx = new SimpleNamespaceContext(); 
       nsCtx.bindNamespaceUri("ns", "http://c1.net.corbis.com/"); 
       xPath.setNamespaceContext(nsCtx); 
       list = (NodeList) xPath.evaluate("//ns:URL128/@Value", source, XPathConstants.NODESET); 
      } catch (Exception ex) 
      { 
       System.out.println(ex.getMessage()); 
      } 
      for (int i = 0; i < list.getLength(); i++) 
      { 
       System.out.println(list.item(i).getTextContent()); 
      } 

Answer 3

有一个稍微容易的解决了这个，不涉及将硬编码的URI引用在你的代码......这简直是解析设置为false名称空间感知属性的文件...

String xmlData = "<SearchResponse xmlns='http://c1.net.corbis.com/'><searchResultDataXML><SearchResultData><SearchRequestUID Scope='Public' Type='Guid' Value='{cded773c-c4b7-4dd8-aaee-8e5b8b7a2475}'/><StartPosition Scope='Public' Type='Long' Value='1'/><EndPosition Scope='Public' Type='Long' Value='50'/><TotalHits Scope='Public' Type='Long' Value='323636'/></SearchResultData></searchResultDataXML><imagesXML><Images><Image><ImageUID Scope='Public' Type='Guid' Value='{a6f6d3e2-2c3f-4502-9741-eae2e1bb573a}'/><CorbisID Scope='Public' Type='String' Value='42-25763849'/><Title Scope='Public' Type='String' Value='Animals figurines'/><CreditLine Scope='Public' Type='String' Value='© Ocean/Corbis'/><IsRoyaltyFree Scope='Public' Type='Boolean' Value='True'/><AspectRatio Scope='Public' Type='String' Value='0.666667'/><URL128 Scope='Public' Type='String' Value='http://cachens.corbis.com/CorbisImage/thumb/25/76/38/25763849/42-25763849.jpg'/></Image></Images></imagesXML></SearchResponse>"; 
InputSource source = new InputSource(new StringReader(xmlData)); 

// create doc instance instead of passing source straight to XPath... 
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); 
factory.setNamespaceAware(false); // must be false 
DocumentBuilder builder = factory.newDocumentBuilder(); 
final Document doc = builder.parse(source); 

XPath xPath = XPathFactory.newInstance().newXPath(); 

// use doc instead 
NodeList list = (NodeList) xPath.evaluate("//URL128/@Value", doc, 
     XPathConstants.NODESET); 

for (int i = 0; i < list.getLength(); i++) { 
    System.out.println(list.item(i).getTextContent()); 
}