如何獲取NodeList中每個節點的第一個子節點的值？

Question

想要獲取每個元素的第一個子元素的元素名稱和值。 但是我得到空值。 我對XML來說還很陌生，我很困惑，只是想讓某些字體能正常工作。 大約有15個孩子，它們都被稱為“ DEvent”，我希望我的輸出是：

事件：周三步道

事件：弓-狗猛撲！

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顯示結果-

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

這是一個工作示例。 您代碼中的firstChild是一個#Text節點，您需要獲取該節點的nextSibling（）（因此，您的事件節點畢竟不是第一個節點）：

    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");
        }
    }

請注意，如果您不執行其他空檢查來驗證xml是否具有正確的子節點格式，則此行將非常脆弱。 而且，這不會強制xml中子節點的順序與您期望的順序相同：

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

話雖如此，我認為一種更好的實現方式是使用XPath，它使您可以選擇所需的節點，而無需手動遍歷樹，並且更加緊湊和“故障保護”：

    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");
    }