java - 从URL解析Java中的XML标记名

我试图从URL的xml标记名检索内容，但是我的int numberOfDetails的长度为0。我在做什么错？

//编辑代码

public String[] dumpTitles(String[] xmlFiles) {


        String[] elementsArray = null;
        try {
            URL xmlContent = new URL("http://webdev4.matcmadison.edu/mab/AmazonXML/georgeEliot.xml");
            DocumentBuilder db = DocumentBuilderFactory.newInstance().newDocumentBuilder();
            Document doc = db.parse(new InputSource(xmlContent.openStream()));


            Toast.makeText(this, "xml file: " + xmlContent, 1000).show();

            NodeList detailsNodeList = doc.getElementsByTagName("Details");
            int numberOfDetails = detailsNodeList.getLength();
            String str = String.format("There are %d Details elements", numberOfDetails);
            Log.println(Log.DEBUG, TAG, str);
            Toast.makeText(this, "number of details: " + str, 1000).show();
            elementsArray = getElementByTagName("ProductName", numberOfDetails, detailsNodeList);
        }
        catch (Exception ex) {
            Log.println(Log.DEBUG, TAG, "XML Parsing failed: " + ex.getMessage());
        }

        return elementsArray;

    }

  public String[] getElementByTagName(String detailTagName, int numberOfDetails, NodeList detailsNodeList) throws Exception {
      String[] elementsArray = null;
      ArrayList<String> elementsArrayList = new ArrayList<String>();
      Toast.makeText(this, "TEST2", 1000).show();
        for (int k = 0; k < numberOfDetails; k++) {
            Toast.makeText(this, "TEST3", 1000).show();
            Element nDetails = (Element)detailsNodeList.item(k);
            NodeList elementNodeList = ((Document) nDetails).getElementsByTagName(detailTagName);
            Node nodeName = elementNodeList.item(k);
            String nodeString = String.format("%s", nodeName);
            elementsArrayList.add(nodeString);
            elementsArray = elementsArrayList.toArray(elementsArray);
            Log.println(Log.DEBUG, TAG, nodeString);
            Toast.makeText(this, "TEST4", 1000).show();
            Toast.makeText(this, "ELEMENT" + elementsArray[0], 1000).show();

        }

        return elementsArray;
}

//原始代码
    字符串xmlContent =“ http://webdev4.matcmadison.edu/mab/AmazonXML/georgeEliot.xml”；
    Log.println（Log.DEBUG，TAG，“ FILE NAME：” + xmlContent）;
    String [] elementsArray = null;
    尝试{
    DocumentBuilder db = DocumentBuilderFactory.newInstance（）。newDocumentBuilder（）;
    Toast.makeText（this，“ xml file：” + xmlContent，1000）.show（）;
    文档doc = db.parse（new InputSource（new StringReader（xmlContent）））;
    NodeList detailsNodeList = doc.getElementsByTagName（“ Details”）;
    int numberOfDetails = detailsNodeList.getLength（）;

最佳答案

您不应该使用StringReader来读取url。 StringReader读取您在构造函数中传递的字符串，它不会从Web下载文件。您可以改用URL类：

URL xmlContent = new URL("http://webdev4.matcmadison.edu/mab/AmazonXML/georgeEliot.xml");
DocumentBuilder db = DocumentBuilderFactory.newInstance().newDocumentBuilder();
Document doc = db.parse(new InputSource(xmlContent.openStream()));

其它的办法：

您可以使用InputSource中的constructor，其中String：

String pathToDocument = "http://webdev4.matcmadison.edu/mab/AmazonXML/georgeEliot.xml";
Document doc = db.parse(new InputSource(pathToDocument));