即使在java中有名称空间管理，也无法从xml获取节点

下面是我正在处理的xml文件的屏幕截图，我需要从标记扩展名中获取值“switchboardid1”：

下面是我编写的代码：我需要从extensions标签访问属性“switchboardid1”。我得到的回报总是空的。请更正我的代码并帮助我理解

我有NamespaceContext类来返回类'HardcodedNamespaceResolver'中的名称空间，它正确地返回了nfh名称空间的值

 public void test() throws Throwable
  {

 String xpath="//ElectricalProject/Equipments/Equipment/Extensions/Extension/nfh:extensionProperty[@name='switchboardId']";
Node node = GetNodeFromXml("PutNFInProj.xml",xpath);

Element ele = (Element) node;
System.out.println(ele.getNodeValue().toString());
   }

//Function to GET a single Node from xml file wrt to xpath defined
 public Node GetNodeFromXml(String XmlFileName, String xPathExpression) throws Throwable 
 {
     DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
     DocumentBuilder builder = factory.newDocumentBuilder();
     Document doc = builder.parse(GetDataFile(XmlFileName));
     ((org.w3c.dom.Document) doc).getDocumentElement().normalize();



     XPath xPath =  XPathFactory.newInstance().newXPath();
     xPath.setNamespaceContext(new HardcodedNamespaceResolver());
     NodeList nodeList = (NodeList) xPath.evaluate(xPathExpression,doc,XPathConstants.NODESET);


     switch (nodeList.getLength()) 
     {
        case 0:
            {
                log.error("In Function: GetNodeFromXml - There are no nodes with respect to given xpath, Please Check the Xpath");
                return null;
            }
        case 1:
            {
                Node nNode = nodeList.item(0);
                return nNode;   
            }

        default:
            {
                log.error("In Function: GetNodeFromXml- There are more than one nodes with respect to given xpath");
                return null;
            }
    }


 }

}SimpleXml可以做到：

final String yourxml = ...
final SimpleXml simple = new SimpleXml();
System.out.println(getSwitchBoardId(simple.fromXml(yourxml)));

private static String getSwitchBoardId(final Element element) {
    return element.children.get(2).children.get(0).children.get(4).children.get(0).children.get(0).text;
}

将输出：

switchboardid1

来自maven central：

<dependency>
    <groupId>com.github.codemonstur</groupId>
    <artifactId>simplexml</artifactId>
    <version>1.4.0</version>
</dependency>

com.github.codemontur
simplexml
1.4.0