黑莓-加载/等待动画屏幕

费明,安东尼+1.谢谢大家,你给了我部分答案。
我的最终解决方案:

1.创建或生成( free Ajax loading gif generator )动画并将其添加到项目中。

2.创建ResponseCallback接口(参见 Coderholic - Blackberry WebBitmapField )接收线程执行结果:

public interface ResponseCallback {
    public void callback(String data);  
}

3.创建一个类来处理后台线程作业。在我的例子中,是HTTP请求:

public class HttpConnector 
{
  static public void HttpGetStream(final String fileToGet,
    final ResponseCallback msgs) {
    Thread t = new Thread(new Runnable() {
      public void run() {
        HttpConnection hc = null;
    DataInputStream din = null;
    try {
      hc = (HttpConnection) Connector.open("http://" + fileToGet);
      hc.setRequestMethod(HttpsConnection.GET);
      din = hc.openDataInputStream();
      ByteVector bv = new ByteVector();
      int i = din.read();
      while (-1 != i) {
        bv.addElement((byte) i);
        i = din.read();
      }
      final String response = new String(bv.toArray(), "UTF-8");
      UiApplication.getUiApplication().invokeLater(
        new Runnable() {
          public void run() {
        msgs.callback(response);
              }
            });
    } 
        catch (final Exception e) {
          UiApplication.getUiApplication().invokeLater(
            new Runnable() {
              public void run() {
                msgs.callback("Exception (" + e.getClass() + "): " 
                  + e.getMessage());
              }
            });
        } 
        finally {
          try {
            din.close();
            din = null;
            hc.close();
            hc = null;
          }
          catch (Exception e) {
          }
        }
      }
    });
  t.start();
  }
}

4.创建waitscreen(全屏和 AnimatedGIFField 带ResponseCallback接口):

public class WaitScreen extends FullScreen implements ResponseCallback 
{
    StartScreen startScreen;
    private GIFEncodedImage _image;
    private int _currentFrame;
    private int _width, _height, _xPos, _yPos;
    private AnimatorThread _animatorThread;
    public WaitScreen(StartScreen startScreen) {
        super(new VerticalFieldManager(), Field.NON_FOCUSABLE);
        setBackground(
            BackgroundFactory.createSolidTransparentBackground(
                Color.WHITE, 100));
        this.startScreen = startScreen;
        EncodedImage encImg = 
          GIFEncodedImage.getEncodedImageResource("ajax-loader.gif");
        GIFEncodedImage img = (GIFEncodedImage) encImg;

        // Store the image and it's dimensions.
        _image = img;
        _width = img.getWidth();
        _height = img.getHeight();
        _xPos = (Display.getWidth() - _width) >> 1;
        _yPos = (Display.getHeight() - _height) >> 1;
        // Start the animation thread.
        _animatorThread = new AnimatorThread(this);
        _animatorThread.start();
        UiApplication.getUiApplication().pushScreen(this);
    }

    protected void paint(Graphics graphics) {
        super.paint(graphics);
            // Draw the animation frame.
            graphics
              .drawImage(_xPos, _yPos, _image
                .getFrameWidth(_currentFrame), _image
                  .getFrameHeight(_currentFrame), _image,
                _currentFrame, 0, 0);
    }

    protected void onUndisplay() {
        _animatorThread.stop();
    }

    private class AnimatorThread extends Thread {
        private WaitScreen _theField;
        private boolean _keepGoing = true;
        private int _totalFrames, _loopCount, _totalLoops;
        public AnimatorThread(WaitScreen _theScreen) {
            _theField = _theScreen;
            _totalFrames = _image.getFrameCount();
            _totalLoops = _image.getIterations();

        }

        public synchronized void stop() {
            _keepGoing = false;
        }

        public void run() {
            while (_keepGoing) {
                // Invalidate the field so that it is redrawn.
                UiApplication.getUiApplication().invokeAndWait(
                  new Runnable() {
                    public void run() {
                        _theField.invalidate();
                    }
                });
                try {
                  // Sleep for the current frame delay before
                  // the next frame is drawn.
                  sleep(_image.getFrameDelay(_currentFrame) * 10);
                } catch (InterruptedException iex) {
                } // Couldn't sleep.
                // Increment the frame.
                ++_currentFrame;
                if (_currentFrame == _totalFrames) {
                  // Reset back to frame 0 
                  // if we have reached the end.
                  _currentFrame = 0;
                  ++_loopCount;
                  // Check if the animation should continue.
                  if (_loopCount == _totalLoops) {
                    _keepGoing = false;
                  }
                }
            }
        }

    }

    public void callback(String data) {
        startScreen.updateScreen(data);
        UiApplication.getUiApplication().popScreen(this);
    }
}

5.最后,创建开始屏幕调用httpconnector.httpgetstream并显示waitscreen:

public class StartScreen extends MainScreen
{
    public RichTextField text;
    WaitScreen msgs;
    public StartScreen() {       
        text = new RichTextField();
        this.add(text);
    }

    protected void makeMenu(Menu menu, int instance) {
        menu.add(runWait);
        super.makeMenu(menu, instance);
    }

    MenuItem runWait = new MenuItem("wait", 1, 1) {
        public void run() {
            UiApplication.getUiApplication().invokeLater(
                new Runnable() {
                    public void run() {
                        getFile();
                    }
            });             
        }
    };

    public void getFile() {
        msgs = new WaitScreen(this);
        HttpConnector.HttpGetStream(
            "stackoverflow.com/faq", msgs);                 
    }

    //you should implement this method to use callback data on the screen.
    public void updateScreen(String data)
    {
        text.setText(data);
    }
}

更新: 另一个解决方案 naviina.eu: A Web2.0/Ajax-style loading popup in a native BlackBerry application

这种情况的基本模式是:

让一个线程运行一个循环,该循环更新一个变量(例如动画图像的帧索引),然后在绘制图像的字段上调用invalidate(无效),然后休眠一段时间。无效将对字段的重新绘制进行排队。

在字段的绘制方法中,读取变量并绘制适当的图像帧。

伪代码(不是完全完整的,但为了给你一个想法):

public class AnimatedImageField extends Field implements Runnable {

   private int currentFrame;
   private Bitmap[] animationFrames;

   public void run() {
     while(true) {
       currentFrame = (currentFrame + 1) % animationFrames.length;
       invalidate();
       Thread.sleep(100);
      }
    }

   protected void paint(Graphics g) {
      g.drawBitmap(0, 0, imageWidth, imageHeight, animationFrames[currentFrame], 0, 0);
    }
  }

注意这里我还使用了一组位图,但是EncodeDimage允许您将动画GIF视为一个对象,并且包括获取特定帧的方法。

编辑:为了完整性:将其添加到弹出屏幕(如fermin的答案)或直接覆盖屏幕创建您自己的对话框。独立线程是必需的,因为RIM API不是线程安全的:您需要在事件线程上执行所有与UI相关的操作(或者在保持事件锁的同时,请参见 BlackBerry UI Threading - The Very Basics

这是加载屏幕的简单代码….

                HorizontalFieldManager popHF = new HorizontalFieldManager();
                popHF.add(new CustomLabelField("Pls wait..."));
                final PopupScreen waitScreen = new PopupScreen(popHF);
                new Thread()
                {
                    public void run() 
                    {

                        synchronized (UiApplication.getEventLock()) 
                        {
                            UiApplication.getUiApplication().pushScreen(waitScreen);
                        }
                       //Here Some Network Call 

                       synchronized (UiApplication.getEventLock()) 
                        {
                            UiApplication.getUiApplication().popScreen(waitScreen);
                        }
                     }
                 }.start();

如果只是一个动画,你能展示一个 animated gif 在弹出窗口上,并在加载操作完成时关闭它?

最简单的方法可能是使用标准GaugeField,设置样式GaugeField.Percent。这会给你一个进度条。将此添加到弹出屏幕,它将位于内容的顶部。比如……

private GaugeField _gaugeField;
private PopupScreen _popup;

public ProgressBar() {    
    DialogFieldManager manager = new DialogFieldManager();
    _popup = new PopupScreen(manager);
    _gaugeField = new GaugeField(null, 0, 100, 0, GaugeField.PERCENT);    
    manager.addCustomField(_gaugeField);
}

然后有一个更新方法,它将使用_GaugeField.setValue(newValue);来更新进度条。

我通常从执行工作的线程调用这个(在您的例子中,每次操作完成时,都会更新进度条)。

我建议看一下这个简单的实现。我喜欢这个,但从未用过。可能对你有帮助。

link text

如果您至少使用BB OS 6.0,那么ActivityIndicator是一个不错的选择。

http://www.brighthub.com/mobile/blackberry-platform/articles/94258.aspx

http://docs.blackberry.com/en/developers/deliverables/17966/Screen_APIs_1245069_11.jsp