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個，也可以有很多。當我在SearchResponse元素上包含xmlns ='http：//c1.net.corbis.com/'時，我得到一個空的NodeList，但是當我刪除該名稱空間元素時，它工作正常。有沒有我錯過的配置？

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，長話短說，你需要提供一個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()); 
} 

這似乎是唯一的方法XPath需要我們實現在這種情況下是getNamespaceURI(String prefix)。

請注意，在這種情況下，「c：URL128」中的實際前綴並不重要 - 您可以輕鬆使用「：URL128」。當你的在你的XML中有多個命名空間時，區分它們變得很重要（如果元素相對較少，則使用Map或一系列if-then-else）。

如果您不能或不想硬代碼，你可以自己從XML文檔中提取出來，但需要多一點的代碼前綴...

也this blog post詳情請見。下面

Answer 2

是實現的兩種方式是什麼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

有一個稍微容易的解決了這個，不涉及將硬編碼的URI引用在你的代碼......這簡直是解析設置爲false名稱空間感知屬性的文件...

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()); 
}