Java DOM xml无法得到孩子

我的 XML看起来像这样：

<ConnProf ConnProfID="1111">
  <ConnNum>1</ConnNum>
  <IsMSPA>false</IsMSPA>
  <IsArray>false</IsArray>
  <IsDDOR>false</IsDDOR>

  <Subsystem SSID="2222"ConnProfID="3333">
    <SSName>AA</SSName>
    <GenericSSName>AA</GenericSSName>
    <ConnFuncAddr>aaa</ConnFuncAddr>
    <DSSNum>22</DSSNum>
    <isRemoved>false</isRemoved>
  </Subsystem>

  <Subsystem SSID="4444" ConnProfID="5555">
    <SSName>BBBB</SSName>
    <GenericSSName>BB</GenericSSName>
    <ConnFuncAddr>bbbbbb</ConnFuncAddr>
    <DSSNum>44</DSSNum>
    <isRemoved>false</isRemoved>
  </Subsystem>

我无法获得ConnNum,IsMSPA,IsArray和IsDDOR.
我尝试使用ConnNum：

//get ConnNum
                Node n = doc.getFirstChild();
                if (n.hasChildNodes())
                    System.out.println(n.getFirstChild().getNodeValue());
                else 
                    System.out.println(n.getNodeValue());

但是当我期待1时它只返回null.

import java.io.IOException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

public class test 
{
    public static void main(String[] args)
    {
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();

        try 
        {
            DocumentBuilder db = dbf.newDocumentBuilder();

            for (int i = 1; i <= 8; i++)
            {
                Document doc = db.parse("file" + i + ".xml");

                doc.getDocumentElement ().normalize ();
                System.out.println ("Root element of the doc is " + doc.getDocumentElement().getNodeName());

                //get ConnNum
                Node n = doc.getFirstChild();
                if (n.hasChildNodes())
                    System.out.println(n.getFirstChild().getNodeValue());
                else 
                    System.out.println(n.getNodeValue());

                NodeList listOfSubsystems = doc.getElementsByTagName("Subsystem");
                int totalSubsystems = listOfSubsystems.getLength();

                if (totalSubsystems == 0)
                    continue;
                else
                {
                    System.out.println("Total number of subsystems : " + totalSubsystems + "n");

                    Dish dish = new Dish();

                    for(int s=0; s < listOfSubsystems.getLength() ; s++)
                    {
                        Node firstPersonNode = listOfSubsystems.item(s);

                        if(firstPersonNode.getNodeType() == Node.ELEMENT_NODE)
                        {
                            Element firstPersonElement = (Element)firstPersonNode;

                            printElement(firstPersonElement,"SSName");
                            printElement(firstPersonElement,"GenericSSName");
                            printElement(firstPersonElement,"ConnFuncAddr");
                            printElement(firstPersonElement,"DSSNum");
                            printElement(firstPersonElement,"SCNum");
                            printElement(firstPersonElement,"SCAcronym");
                            printElement(firstPersonElement,"PassNum");
                            printElement(firstPersonElement,"FzCode");
                            printElement(firstPersonElement,"isRemoved");
                            System.out.println("------------------");
                        }
                    }
                    System.out.println("n==============================");
                }

            }
        }
        catch(ParserConfigurationException pce) 
        {
            pce.printStackTrace();
        }
        catch(SAXException se) 
        {
            se.printStackTrace();
        }
        catch(IOException ioe) 
        {
            ioe.printStackTrace();
        }
    }   

    public static void printElement(Element a,String name)
    {
        NodeList elementList = a.getElementsByTagName(name);
        Element b = (Element)elementList.item(0);

        if (b != null)
        {
            NodeList list = b.getChildNodes();
            System.out.println( ((Node)list.item(0)).getNodeValue().trim() );
        }
    }
}

解决方法

Nodes有一个类型,你可以迭代所有检查Element节点类型的子节点来获取实际元素的句柄.

编辑：这将打印您之后的值.它在Element节点上进行过滤,然后对每个节点的第一个子节点(包含文本的节点)进行过滤.

NodeList nodeList = n.getChildNodes();
for (int j = 0; j < nodeList.getLength(); j++) {
    Node childNode = nodeList.item(j);
    if (childNode.getNodeType() == Node.ELEMENT_NODE) {
        System.out.println(childNode.getNodeName() + " " + childNode.getFirstChild().getNodeValue());
    }
}

此外,正如@Steve Townsend正确编写的那样,如果您使用的是Java 1.5或更高版本,则可以使用getTextContent()而不是childNode.getFirstChild().getNodeValue().

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