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我在这里使用了一个关于列表视图的教程，它获取了一些信息，比如艺术家的名字......以及艺术家图像的 URL 和制作列表视图。

    <music>
    <song>
    <id>1</id>
    <title>Someone Like You</title>
    <artist>Adele</artist>
    <duration>4:47</duration>
    <thumb_url>http://api.androidhive.info/music/images/adele.png</thumb_url>
    </song>
    <song>
    <id>2</id>
    <title>Space Bound</title>
    <artist>Eminem</artist>
    <duration>4:38</duration>
    <thumb_url>
    http://api.androidhive.info/music/images/eminem.png
    </thumb_url>
    </song>
    .
    .
    .

我想添加另一个名为 mp3 的节点，并将歌曲的 URL 提供给 XML 中的每个数组，以便通过单击列表的每一行来下载正确的 mp3 文件。如下所示：

<music>
<song>
<id>1</id>
<title>Someone Like You</title>
<artist>Adele</artist>
<duration>4:47</duration>
<thumb_url>http://api.androidhive.info/music/images/adele.png</thumb_url>
**<mp3> some URL1 </mp3>**
</song>
<song>
<id>2</id>
<title>Space Bound</title>
<artist>Eminem</artist>
<duration>4:38</duration>
<thumb_url>http://api.androidhive.info/music/images/eminem.png</thumb_url>
**<mp3> some URL2 </mp3>**
</song>
.
.
.

我更改了如下所示的主要 java 代码，但我可以下载定义为之前输入的直接 URL的“file_url”(new DownloadFileFromURL().execute( file_url );) 字符串。请帮助我从 xml 获取 mp3 URL 以供下载。

    public class CustomizedListView extends Activity {
// All static variables
static final String URL = "http://api.androidhive.info/music/music.xml";
// XML node keys
static final String KEY_SONG = "song"; // parent node
static final String KEY_ID = "id";
static final String KEY_TITLE = "title";
static final String KEY_ARTIST = "artist";
static final String KEY_DURATION = "duration";
static final String KEY_THUMB_URL = "thumb_url";

ListView list;
LazyAdapter adapter;

  // Progress Dialog
private ProgressDialog pDialog;
  // Progress dialog type (0 - for Horizontal progress bar)
public static final int progress_bar_type = 0;
  // File url to download
private static String file_url = "the URL of the file that I don't want to use this method for downloading the file";


@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);


    ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();

    XMLParser parser = new XMLParser();
    String xml = parser.getXmlFromUrl(URL); // getting XML from URL
    Document doc = parser.getDomElement(xml); // getting DOM element

    NodeList nl = doc.getElementsByTagName(KEY_SONG);
    // looping through all song nodes <song>
    for (int i = 0; i < nl.getLength(); i++) {
        // creating new HashMap
        HashMap<String, String> map = new HashMap<String, String>();
        Element e = (Element) nl.item(i);
        // adding each child node to HashMap key => value
        map.put(KEY_ID, parser.getValue(e, KEY_ID));
        map.put(KEY_TITLE, parser.getValue(e, KEY_TITLE));
        map.put(KEY_ARTIST, parser.getValue(e, KEY_ARTIST));
        map.put(KEY_DURATION, parser.getValue(e, KEY_DURATION));
        map.put(KEY_THUMB_URL, parser.getValue(e, KEY_THUMB_URL));

        // adding HashList to ArrayList
        songsList.add(map);
    }


    list=(ListView)findViewById(R.id.list);

    // Getting adapter by passing xml data ArrayList
    adapter=new LazyAdapter(this, songsList);        
    list.setAdapter(adapter);





    // Click event for single list row
    list.setOnItemClickListener(new OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> parent, View view,
                int position, long id) {
            new DownloadFileFromURL().execute(file_url);



        }
    }); 

}   
/**
 * Showing Dialog
 * */
@Override
protected Dialog onCreateDialog(int id) {
    switch (id) {
    case progress_bar_type:
        pDialog = new ProgressDialog(this);
        pDialog.setMessage("Downloading file. Please wait...");
        pDialog.setIndeterminate(false);
        pDialog.setMax(100);
        pDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
        pDialog.setCancelable(true);
        pDialog.show();
        return pDialog;
    default:
        return null;
    }
}

/**
 * Background Async Task to download file
 * */
class DownloadFileFromURL extends AsyncTask<String, String, String> {

    /**
     * Before starting background thread
     * Show Progress Bar Dialog
     * */
    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        showDialog(progress_bar_type);
    }

    /**
     * Downloading file in background thread
     * */
    @Override
    protected String doInBackground(String... f_url) {
        int count;
        try {
            URL url = new URL(f_url[0]);
            URLConnection conection = url.openConnection();
            conection.connect();
            // getting file length
            int lenghtOfFile = conection.getContentLength();

            // input stream to read file - with 8k buffer
            InputStream input = new BufferedInputStream(url.openStream(), 8192);

            // Output stream to write file
            OutputStream output = new  FileOutputStream("/sdcard/Downloadmanager.zip");

            byte data[] = new byte[1024];

            long total = 0;

            while ((count = input.read(data)) != -1) {
                total += count;
                // publishing the progress....
                // After this onProgressUpdate will be called
                publishProgress(""+(int)((total*100)/lenghtOfFile));

                // writing data to file
                output.write(data, 0, count);
            }

            // flushing output
            output.flush();

            // closing streams
            output.close();
            input.close();

        } catch (Exception e) {
            Log.e("Error: ", e.getMessage());
        }

        return null;
    }

    /**
     * Updating progress bar
     * */
    protected void onProgressUpdate(String... progress) {
        // setting progress percentage
        pDialog.setProgress(Integer.parseInt(progress[0]));
   }

    /**
     * After completing background task
     * Dismiss the progress dialog
     * **/
    @Override
    protected void onPostExecute(String file_url) {
        // dismiss the dialog after the file was downloaded
        dismissDialog(progress_bar_type);


    }

}

}

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