音量修飾鍵控制的音頻流

轉自

http://rainhomepage.appspot.com/2010/05/hardware-volume-controls-audio-stream-setvolumecontrolstream

 

當開發多媒體應用或者遊戲應用的時候，需要使用音量修飾鍵來設定程式的音量大小。在Android系統中有多中音頻流，通過Activity中的函數
setVolumeControlStream(int
streamType)可以設定該Activity中音量修飾鍵控制的音頻流，一般在onCreate函數中設定。

Android中有如
下幾種音頻流：

• AudioManager.STREAM_MUSIC  /** The audio stream for music playback
  */
• AudioManager.STREAM_RING /** The audio stream for the phone ring */
• AudioManager.STREAM_ALARM  /** The audio stream for alarms */
• AudioManager.STREAM_NOTIFICATION /** The audio stream for
  notifications */
• AudioManager.STREAM_SYSTEM  /** The audio stream for system sounds
  */
• AudioManager.STREAM_VOICECALL /** The audio stream for phone calls
  */

setVolumeControlStream函數描述：

void
android.app.Activity
.setVolumeControlStream(int
streamType)

Suggests an audio stream whose volume should be changed by the
hardware
volume controls.

The suggested audio stream will be tied to the window of this
Activity. If
the Activity is switched, the stream set here is no longer the suggested
stream.
The client does not need to save and restore the old suggested stream
value in
onPause and onResume.

Parameters:

streamType
The type of the audio stream whose
volume should be
changed by the hardware volume controls. It is not guaranteed that the
hardware
volume controls will always change this stream's volume (for example, if
a call
is in progress, its stream's volume may be changed instead). To reset
back to
the default, use AudioManager.USE_DEFAULT_STREAM_TYPE

.