java - J2ME - 使用 javax.microedition.amms.control.camera.CameraControl；是否可以禁用快门声音？

Question

在我的 Blackberry 应用程序中，我实现了摄像头，并想用我自己的声音替换默认的快门声音。我想我可以通过使用 enableShutterFeedback(false) 方法使默认相机声音静音然后播放我自己的声音，或者在相机被激活之前立即播放我的声音来做到这一点。

private void initializeCamera()
    {
        try
        {
            // Create a player for the Blackberry's camera
            Player player = Manager.createPlayer( "capture://video" );

            // Set the player to the REALIZED state (see Player javadoc)
            player.realize();

            // Grab the video control and set it to the current display
            _videoControl = (VideoControl)player.getControl( "VideoControl" );

            if (_videoControl != null)
            {
                // Create the video field as a GUI primitive (as opposed to a
                // direct video, which can only be used on platforms with
                // LCDUI support.)
                _videoField = (Field) _videoControl.initDisplayMode (VideoControl.USE_GUI_PRIMITIVE, "net.rim.device.api.ui.Field");
                _videoControl.setDisplayFullScreen(true);
                _videoControl.setVisible(false);
            }
            cc = (CameraControl)player.getControl("CameraControl");
            cc.enableShutterFeedback(false);
            // Set the player to the STARTED state (see Player javadoc)
            player.start();

        }
        catch(Exception e)
        {
            MyApp.errorDialog("ERROR " + e.getClass() + ":  " + e.getMessage());
        }
    }

这会导致空指针异常，但无法弄清楚是什么原因导致的，摄像头的视频没有显示。如果我删除粗体的 CameraControl 代码，则会显示相机的视频。有什么想法可以消除快门声吗？我尝试用 VolumeControl 代替 CameraControl，结果相同，空指针。

Answer 1

CameraControl 代码给出了一个 NPE，因为 player.getControl 返回 null，它这样做是因为字符串参数不正确。试试这个:

CameraControl control = (CameraControl) p.getControl("javax.microedition.amms.control.camera.CameraControl");