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在本教程中

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<td width="90%"><font size="4" face="Verdana, Arial, Helvetica"><b>Download 类</b></font></td><td width="200" align="right"><font size="1" face="Verdana, Arial, Helvetica"><nobr>   第 5 页（共5 页）</nobr></font></td>
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<p>在上一页中，我简短地讨论了用于适度多线程的技术。下面的代码清单提供了详细的实现。以下是 <code>Download</code> 类的代码：</p>
<pre>
<code style="font-family: Courier New, Courier, monospace; font-size: 12">
public class Download implements Runnable
{
  private UniStock     midlet;
  private String       baseURL;		 // Retrieve URL from JAD file.
  private String       URL;

  private boolean      interrupted;

  // For a Class object, only one of the following
  // objects is not null.
  private   FormAdd  formAdd;
  private   FormView formView;

  // We only allow one download listener so far.
  DownloadListener dl;
  boolean hasListener;

  public Download(UniStock midlet) {
    this.midlet = midlet;
    baseURL = midlet.getAppProperty(midlet.URL_KEY);
  }

  ...

  /**
   * Thread starts from here!
  */
  public void run() {
    try {
      getInfo();
    }catch(Exception e) {
      if(midlet.DEBUG)
        midlet.debug("Exception caught: " + e.toString());
    }
  }

  public void setInterrupted() {
    interrupted = true;
    if(midlet.DEBUG)
      midlet.debug("Interrupted!");
  }

  public boolean interrupted() {
    return interrupted;
  }

  /**
   * Do the real work here.
   */
  private void getInfo() throws Exception {
    HttpConnection http = null;
    InputStream is = null;
    boolean ret = false;

    if(formAdd != null) {
      URL = baseURL + "?E=" +
formAdd.choiceExchanges.getSelectedIndex() +
		     "&amp;S=" + formAdd.textCode.getString() + "&amp;T=0";
    }else if(formView != null &amp;&amp; formView.s != null) {
      // Create view baseURL....
      ...
    }

    if(UniStock.DEBUG)
      UniStock.debug("Connecting to: " + URL);

    try{
      http = (HttpConnection) Connector.open(URL);
      http.setRequestMethod(HttpConnection.GET);
      if(hasListener)
        dl.setProgress(1, 10);

      if(interrupted)
        throw new InterruptedException();

      is = http.openInputStream();
      if(hasListener)
        dl.setProgress(2, 10);
      if(UniStock.DEBUG)
        UniStock.debug("Connecting to: " + URL);

      String str;      // Temp buffer.
      int length = (int) http.getLength();
      if(hasListener)
        dl.setProgress(3, 10);

      if(interrupted)
        throw new InterruptedException();

      if(length != -1) { // Length valid.
        byte data[] = new byte[length];
        is.read(data);
        str = new String(data);
      }else{		 // Length not available.
        ByteArrayOutputStream bs = new ByteArrayOutputStream();

        int ch;
        while((ch = is.read()) != -1)
		   bs.write(ch);

        str = new String(bs.toByteArray());
          bs.close();
      }

      if(interrupted)
        throw new InterruptedException();

      if(UniStock.DEBUG)
        UniStock.debug("Got Data:&gt;" + str + "&lt;");

      // String downloaded.....
      // Process data here.
      ...

      if(hasListener)
        dl.setProgress(10, 10);

      // Alert the user.
      // AlertType.INFO.playSound(midlet.display);

    } catch (IOException e) {
      if(midlet.DEBUG)
        midlet.debug("Downloading error: " + e.toString());
      if(formAdd != null) {
        formAdd.stockOK = false;
      }else if(formView != null) {

      }
    } finally {
     if(formAdd != null)
       formAdd.process();
     if(formView != null)
       ;		 // Do something.

     /// Clean up.
     if(is != null)
       is.close();
     if(http != null)
       http.close();

     if(dl != null)

       dl.onFinish();
    }

  } // End function getInfo();

}


         </code>
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