Question

我想获取每个元素的第一个子元素的元素名称和值。但我得到空值。我对XML非常陌生，我很难过，只是想尝试使用漂亮的字体。大约有15个孩子到根，他们都被称为“DEvent”，我希望我的输出是：

活动：周三徒步旅行

事件：哇 - 狗嘘！

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。代码中的firstChild是一个#Text节点，你需要得到该节点的nextSibling（）（所以你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，如果不进行额外的空检查以验证xml是否与正确的子节点组合良好，则此行将是脆弱的。并且，这不会强制xml中子节点的顺序按照您期望的顺序执行：

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

话虽如此，我认为更好的实现方法是使用XPath，它允许您选择所需的节点，而无需在树中手动遍历，并且更紧凑，“故障安全”：

    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");
    }

如何在NodeList中获取每个节点的第一个子节点的值？

1 个答案: