如何获取NodeList中每个节点的第一个子节点的值？

Question

想要获取每个元素的第一个子元素的元素名称和值。 但是我得到空值。 我对XML来说还很陌生，我很困惑，只是想让某些字体能正常工作。 大约有15个孩子，它们都被称为“ DEvent”，我希望我的输出是：

事件：周三步道

事件：弓-狗猛扑！

等等

    <DNREvents>
<DEvent>
<event eid="1">Wednesday Trail Walks</event>
<date>2/03/2016</date>
<time>1-2:30 PM</time>
<description>...</description>
<location>Brown's Creek State Trail</location>
<cost>Free</cost>
<infoPhone>651-231-6968</infoPhone>
<infoEmail>LindaRadimecky@state.mn.us</infoEmail>
</DEvent>
<DEvent>
<event eid="2">BOW - Dog Mushing!</event>
<date>2/04/2016 thru 2/07/2016</date>
<time>Unknown</time>
<description>
This off the grid adventure is for those who want to actively participate in every aspect of learning to run your own small team of sled dogs through miles and miles of beautiful trails in the remote wilderness of northern Minnesota. Limited to 4 participants
</description>
<location>Grand Marais/Hovland</location>
<cost>$895</cost>
<infoPhone>218-370-0283</infoPhone>
<infoEmail>linda@points_unknown.com</infoEmail>
</DEvent>
<DEvent>...</DEvent>
<DEvent>...</DEvent>
<DEvent>...</DEvent>
<DEvent>...</DEvent>
<DEvent>...</DEvent>
<DEvent>...</DEvent>
<DEvent>...</DEvent>
<DEvent>...</DEvent>
<DEvent>...</DEvent>
<DEvent>...</DEvent>
<DEvent>...</DEvent>
<DEvent>...</DEvent>
<DEvent>...</DEvent>
</DNREvents>

我的Java显示结果-

Element DNR = root;
        NodeList EventList=DNR.getElementsByTagName("DEvent");
        for (int i=0; i< EventList.getLength();i++)
        {
            Node thisNode = EventList.item(i);
            Node child = thisNode.getFirstChild();
            String x = child.getNodeValue();
            System.out.println(thisNode+ x);
        }

Answer 1

这是一个工作示例。 您代码中的firstChild是一个#Text节点，您需要获取该节点的nextSibling（）（因此，您的事件节点毕竟不是第一个节点）：

    import org.w3c.dom.*;
    import java.io.*;
    import javax.xml.parsers.DocumentBuilderFactory;
    import javax.xml.parsers.DocumentBuilder;

    File xmlFile = new File("/data/test/test.xml");
    DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
    DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
    Document doc = dBuilder.parse(xmlFile);

    NodeList eventList = doc.getElementsByTagName("DEvent");
    for (int i=0; i< eventList.getLength(); i++) {
        Node thisNode = eventList.item(i);

        if(thisNode.hasChildNodes()){
            NodeList event = thisNode.getChildNodes().getFirstChild().getNextSibling();
            String eid = event.getAttributes().getNamedItem("eid");
            String value = event.getFirstChild().getNodeValue();
            System.out.println("EID: " + eid + " Value: " + value + "\n");
        }
    }

请注意，如果您不执行其他空检查来验证xml是否具有正确的子节点格式，则此行将非常脆弱。 而且，这不会强制xml中子节点的顺序与您期望的顺序相同：

NodeList child = thisNode.getChildNodes().getFirstChild().getNextSibling();

话虽如此，我认为一种更好的实现方式是使用XPath，它使您可以选择所需的节点，而无需手动遍历树，并且更加紧凑和“故障保护”：

    XPath xpath = XPathFactory.newInstance().newXPath();
    String expression = "/DNREvents/DEvent/event";
    InputSource inputSource = new InputSource(new BufferedReader(new FileReader("/data/test/test.xml")));
    NodeList eventList = (NodeList) xpath.evaluate(expression, inputSource, XPathConstants.NODESET);

    for (int i=0; i< eventList.getLength(); i++) {
        Node eventNode = eventList.item(i);

        String eid = xpath.evaluate("@eid", eventNode);
        String value = xpath.evaluate("./text()", eventNode);
        System.out.println("EID: " + eid + ", Value: " + value + "\n");
    }