XML 在网站中解析

Question

我正在尝试解析 XML 中的网页并在 logcat 中打印数据，但我的输出是空的。这是我的 XML 结构：

    <?xml version="1.0"?>
<FLIGHTS>
    <FLIGHT airport="b: 3  "
        logo="IG"
        code="IG"
        numero="1234" 
        carrier="AirBerlin"
        city="NEW YORK"
        terminal="Terminal A"
        sched="08:40"
        expect="09:09" 
        tipo_volo="L" stato="J"
    </FLIGHT>
    <FLIGHT airport="c: 3  "
     ....
     .....more...
    </FLIGHT>
</FLIGHTS>

这是我在 AsyncTask 中的 Android 代码：

     @Override
    protected String doInBackground(String... params) {

        try {


            URL url = new URL("http://myurl");
            URLConnection conn = url.openConnection();

            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
            DocumentBuilder builder = factory.newDocumentBuilder();
            Document doc = builder.parse(conn.getInputStream());

            NodeList nodes = doc.getElementsByTagName("FLIGHT");
            for (int i = 0; i < nodes.getLength(); i++) {
                Element element = (Element) nodes.item(i);
              // NodeList title = element.getElementsByTagName("airport");
               // Element line = (Element) title.item(0);
           //     a.add(line.getTextContent());

                Log.d("LOG...", "" + element.getTextContent());
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

在 AndroidManifest 中，我有互联网许可！

谢谢！

Answer 1

您的代码示例有效。 Java 区分大小写。您确定您的 XML 标签名称正确吗？

这是一个使用 w3schools XML 示例的工作示例：

  try {

         URL url = new URL("http://www.w3schools.com/xml/note.xml");
         URLConnection conn = url.openConnection();

         DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
         DocumentBuilder builder = factory.newDocumentBuilder();
         Document doc = builder.parse(conn.getInputStream());

         NodeList nodes = doc.getElementsByTagName("note");
         for (int i = 0; i < nodes.getLength(); i++) {
            Element element = (Element) nodes.item(i);
            // NodeList title = element.getElementsByTagName("airport");
            // Element line = (Element) title.item(0);
            // a.add(line.getTextContent());

            System.out.println(element.getTextContent());
         }
      } catch (Exception e) {
         e.printStackTrace();
      }

现在使用您的 XML 示例和 Joop Eggen's 答案：

try {

     URL url = new URL("http://myurl");
     URLConnection conn = url.openConnection();

     DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
     DocumentBuilder builder = factory.newDocumentBuilder();
     Document doc = builder.parse(conn.getInputStream());

     NodeList nodes = doc.getElementsByTagName("FLIGHT");
     for (int i = 0; i < nodes.getLength(); i++) {
        Element element = (Element) nodes.item(i);
        String airport = element.getAttribute("airport");

        System.out.println("element " + i + ": airport=" + airport);
     }
  } catch (Exception e) {
     e.printStackTrace();
  }

使用简单文件的示例：

test.xml:

<?xml version="1.0"?>
<FLIGHTS>
    <FLIGHT airport="b: 3  " logo="IG" code="IG" numero="1234"
        carrier="AirBerlin" city="NEW YORK" terminal="Terminal A" sched="08:40"
        expect="09:09" tipo_volo="L" stato="J">
    </FLIGHT>
</FLIGHTS>

Example.java:

import java.io.File;
import java.io.FileInputStream;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;

public class Example {

    public static void main(String[] args) {
    File f = new File("test.xml");
    try {

        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = factory.newDocumentBuilder();
        Document doc = builder.parse(new FileInputStream(f));

        NodeList nodes = doc.getElementsByTagName("FLIGHT");
        for (int i = 0; i < nodes.getLength(); i++) {
        Element element = (Element) nodes.item(i);
        String airport = element.getAttribute("airport");

        System.out.println("element " + i + ": airport='" + airport + "'");
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
    }
}

Answer 2

如果 XML 是正确的，属性 XXX="..." 会有所不同：

Element element = (Element) nodes.item(i);
String airport = element.getAttribute("airport");
if (airport != null) { ...

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