加注: Settings.System.SAFE_HEADSET_VOLUME
Android调整音量方法有两种,一种是渐进式,即像手动按音量键一样,一步一步增加或减少,另一种是直接设置音量值.
下面先分析第一种渐进式的:
1. AudioManager am = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
2. public void adjustStreamVolume (int streamType, int direction, int flags)
3. am.adjustStreamVolume (AudioManager.STREAM_MUSIC, AudioManager.ADJUST_RAISE, AudioManager.FLAG_SHOW_UI);
解释一下三个参数
第一个streamType是需要调整音量的类型,这里设的是媒体音量,可以是:
STREAM_ALARM 警报
STREAM_MUSIC 音乐回放即媒体音量
STREAM_NOTIFICATION 窗口顶部状态栏Notification,
STREAM_RING 铃声
STREAM_SYSTEM 系统
STREAM_VOICE_CALL 通话
STREAM_DTMF 双音多频,不是很明白什么东西
第二个direction,是调整的方向,增加或减少,可以是:
ADJUST_LOWER 降低音量
ADJUST_RAISE 升高音量
ADJUST_SAME 保持不变,这个主要用于向用户展示当前的音量
第三个flags是一些附加参数,只介绍两个常用的
FLAG_PLAY_SOUND 调整音量时播放声音
FLAG_SHOW_UI 调整时显示音量条,就是按音量键出现的那个
0 表示什么也没有
首先跟进AudioManager的adjustStreamVolume()方法可以看到如下代码:
1. public void adjustStreamVolume(int streamType, int direction, int flags) {
2. IAudioService service = getService();
3. try {
4. service.adjustStreamVolume(streamType, direction, flags);
5. catch (RemoteException e) {
6. "Dead object in adjustStreamVolume", e);
7. }
8. }
从代码里面可以看到,这里是调用的AudioService里面的adjustStreamVolume()方法,而AudioService的实现文件是:AudioService.java,其方法实现如下:
1. public void adjustStreamVolume(int streamType, int direction, int flags) {
2. //数据正确性检查
3. //数据正确性检查
4. 。
5. 。
6. 。
7. // If stream is muted, adjust last audible index only
8. int index; //局部变量,保存调整后的音量状态
9. //进行实际的音量调整,在mAudioHandler里面进行。
10. if (streamState.muteCount() != 0) {
11. if (adjustVolume) {
12. streamState.adjustLastAudibleIndex(direction);
13. // Post a persist volume msg
14. sendMsg(mAudioHandler, MSG_PERSIST_VOLUME, streamType,
15. 0, 1, streamState, PERSIST_DELAY);
16. }
17. index = streamState.mLastAudibleIndex;
18. else {
19. if (adjustVolume && streamState.adjustIndex(direction)) {
20. // Post message to set system volume (it in turn will post a message
21. // to persist). Do not change volume if stream is muted.
22. 0, 0,
23. 0);
24. }
25. index = streamState.mIndex;
26. }
27.
28. // UI //画UI,即调整音量时出现的那个ProgressBar
29. mVolumePanel.postVolumeChanged(streamType, flags);
30. // Broadcast Intent //发送广播,广播音量有改变的系统事件
31. sendVolumeUpdate(streamType, oldIndex, index);
32. }
下面先来看看画UI的过程:
跟进VolumePanel,发现这个类是一个handle,在postVolumeChanged()方法里面有如下代码:
1. public void postVolumeChanged(int streamType, int flags) {
2. if (hasMessages(MSG_VOLUME_CHANGED)) return;
3. removeMessages(MSG_FREE_RESOURCES);
4. obtainMessage(MSG_VOLUME_CHANGED, streamType, flags).sendToTarget();
5. }
这里利用了android里面的消息机制来传递消息。对android的消息机制有所了解的应该知道,这个sendToTarget()方法实际上最后的Target就是它本身,也就是VolumePanel这个类本身,因此我们去这个Handle的handleMessage()方法里面查找对于MSG_VOLUME_CHANGED这个类型消息的处理:
1. case MSG_VOLUME_CHANGED: {
2. onVolumeChanged(msg.arg1, msg.arg2);
3. break;
4. }
可以看到,后续是在onVolumeChanged()这个方法里面处理的,其两个参数分别是streamType和flags,其中streamType是要调整的音量类型,而flags是传过来的UI类型。onVolumeChanged()方法代码如下:
1. protected void onVolumeChanged(int streamType, int flags) {
2.
3.
4. if (LOGD) Log.d(TAG, "onVolumeChanged(streamType: " + streamType + ", flags: " + flags + ")");
5.
6. //根据flags的不同,来做不同的处理
7. if ((flags & AudioManager.FLAG_SHOW_UI) != 0) {
8. //UI显示
9. }
10.
11.
12. if ((flags & AudioManager.FLAG_PLAY_SOUND) != 0 && ! mRingIsSilent) {
13. removeMessages(MSG_PLAY_SOUND);
14. //播放声音
15. }
16.
17.
18. if ((flags & AudioManager.FLAG_REMOVE_SOUND_AND_VIBRATE) != 0) {
19. removeMessages(MSG_PLAY_SOUND);
20. removeMessages(MSG_VIBRATE);
21. //停止播放声音和震动
22. }
23.
24.
25. removeMessages(MSG_FREE_RESOURCES);
26. sendMessageDelayed(obtainMessage(MSG_FREE_RESOURCES), FREE_DELAY);
27. }
通过代码可以知道,根据传进去的flags不同,有不同的处理,下面就看看onShowVolumeChanged()方法的处理,也就是ProgressBar的显示:
1. protected void onShowVolumeChanged(int streamType, int flags) {
2. int index = mAudioService.getStreamVolume(streamType);
3. int message = UNKNOWN_VOLUME_TEXT;
4. int additionalMessage = 0;
5. false;
6.
7.
8. if (LOGD) {
9. "onShowVolumeChanged(streamType: " + streamType
10. ", flags: " + flags + "), index: " + index);
11. }
12.
13.
14. // get max volume for progress bar
15. int max = mAudioService.getStreamMaxVolume(streamType);
16.
17.
18. switch (streamType) {
19.
20.
21. case AudioManager.STREAM_RING: { //铃声的处理
22. setRingerIcon();
23. message = RINGTONE_VOLUME_TEXT;
24. Uri ringuri = RingtoneManager.getActualDefaultRingtoneUri(
25. mContext, RingtoneManager.TYPE_RINGTONE);
26. Uri ringTwoUri = RingtoneManager.getActualDefaultRingtoneUri(mContext, RingtoneManager.TYPE_RINGTONE,
27. PhoneFactory.RAW_PHONE_ID);
28. if ((ringuri == null) && (ringTwoUri == null)) {
29. additionalMessage =
30. //com.android.internal.R.string.volume_music_hint_silent_ringtone_selected;
31. com.android.internal.R.string.volume_music_hint_sim1_and_sim2_silent_ringtone_selected;
32. true;
33. else if ((ringuri == null) && (ringTwoUri != null)) {
34. additionalMessage =
35. com.android.internal.R.string.volume_music_hint_silent_sim1_ringtone_selected;
36. else if ((ringuri != null) && (ringTwoUri == null)) {
37. additionalMessage =
38. com.android.internal.R.string.volume_music_hint_sim2_silent_ringtone_selected;
39. }
40. break;
41. }
42.
43.
44. case AudioManager.STREAM_MUSIC: { //音乐声音的处理
45. message = MUSIC_VOLUME_TEXT;
46. if (mAudioManager.isBluetoothA2dpOn()) {
47. additionalMessage =
48. com.android.internal.R.string.volume_music_hint_playing_through_bluetooth;
49. setLargeIcon(com.android.internal.R.drawable.ic_volume_bluetooth_ad2p);
50. else {
51. setSmallIcon(index);
52. }
53. break;
54. }
55.
56.
57. case AudioManager.STREAM_FM: { //FM声音的处理
58. message = FM_VOLUME_TEXT;
59. setSmallIcon(index);
60. break;
61. }
62.
63.
64. case AudioManager.STREAM_VOICE_CALL: { //通话声音的处理
65. /*
66. * For in-call voice call volume, there is no inaudible volume.
67. * Rescale the UI control so the progress bar doesn't go all
68. * the way to zero and don't show the mute icon.
69. */
70. index++;
71. max++;
72. message = INCALL_VOLUME_TEXT;
73. setSmallIcon(index);
74. break;
75. }
76.
77.
78. case AudioManager.STREAM_ALARM: { //闹钟声音的处理
79. message = ALARM_VOLUME_TEXT;
80. setSmallIcon(index);
81. break;
82. }
83.
84.
85. case AudioManager.STREAM_NOTIFICATION: { //Notification声音的处理
86. message = NOTIFICATION_VOLUME_TEXT;
87. setSmallIcon(index);
88. Uri ringuri = RingtoneManager.getActualDefaultRingtoneUri(
89. mContext, RingtoneManager.TYPE_NOTIFICATION);
90. if (ringuri == null) {
91. additionalMessage =
92. com.android.internal.R.string.volume_music_hint_silent_ringtone_selected;
93. true;
94. }
95. break;
96. }
97.
98.
99. case AudioManager.STREAM_BLUETOOTH_SCO: { //蓝牙_sco?不知道是什么东西。。
100. /*
101. * For in-call voice call volume, there is no inaudible volume.
102. * Rescale the UI control so the progress bar doesn't go all
103. * the way to zero and don't show the mute icon.
104. */
105. index++;
106. max++;
107. message = BLUETOOTH_INCALL_VOLUME_TEXT;
108. setLargeIcon(com.android.internal.R.drawable.ic_volume_bluetooth_in_call);
109. break;
110. }
111. }
112.
113.
114. //根据调整的声音不同,显示不同的信息
115. if (!mMessage.getText().equals(messageString)) {
116. mMessage.setText(messageString);
117. }
118.
119.
120. if (additionalMessage == 0) {
121. mAdditionalMessage.setVisibility(View.GONE);
122. else {
123. mAdditionalMessage.setVisibility(View.VISIBLE);
124. mAdditionalMessage.setText(Resources.getSystem().getString(additionalMessage));
125. }
126.
127.
128. if (max != mLevel.getMax()) {
129. mLevel.setMax(max);
130. }
131. //设置ProgressBar的值
132.
133.
134. mToast.setView(mView);
135. mToast.setDuration(Toast.LENGTH_SHORT);
136. 0, 0);
137. mToast.show();
138.
139.
140. // Do a little vibrate if applicable (only when going into vibrate mode)
141. if ((flags & AudioManager.FLAG_VIBRATE) != 0 &&
142. mAudioService.isStreamAffectedByRingerMode(streamType) &&
143. mAudioService.getRingerMode() == AudioManager.RINGER_MODE_VIBRATE &&
144. mAudioService.shouldVibrate(AudioManager.VIBRATE_TYPE_RINGER)) {
145. sendMessageDelayed(obtainMessage(MSG_VIBRATE), VIBRATE_DELAY);
146. }
147. }
在通话声音的处理中,有个setSmallIcon()函数,可以看到,这个是根据不同情况选择ProgressBar上面显示的图片的。
1. private void setSmallIcon(int index) {
2. mLargeStreamIcon.setVisibility(View.GONE);
3. mSmallStreamIcon.setVisibility(View.VISIBLE);
4.
5.
6. 0
7. ? com.android.internal.R.drawable.ic_volume_off_small
8. : com.android.internal.R.drawable.ic_volume_small);
9. }
View view = mView = inflater.inflate(com.android.internal.R.layout.volume_adjust, null);
mLevel就是显示的那个ProgressBar,mLevel = (ProgressBar) view.findViewById(com.android.internal.R.id.level);
从这里我们可以看到,声音调整显示的布局文件是volume_adjust.xml,如果想自己对声音显示的布局进行调整的话,就可以自己手动修改这个布局文件,达到自己想要的效果了。
到这里就把声音调整的UI显示过程分析完了,下面接着来分析声音调整广播发送sendVolumeUpdate():
1. private void sendVolumeUpdate(int streamType, int oldIndex, int index) {
2. 5) / 10;
3. 5) / 10;
4.
5.
6. new Intent(AudioManager.VOLUME_CHANGED_ACTION);
7. intent.putExtra(AudioManager.EXTRA_VOLUME_STREAM_TYPE, streamType);
8. intent.putExtra(AudioManager.EXTRA_VOLUME_STREAM_VALUE, index);
9. intent.putExtra(AudioManager.EXTRA_PREV_VOLUME_STREAM_VALUE, oldIndex);
10.
11.
12. mContext.sendBroadcast(intent);
13. }
可以看到,这里发送了一个广播,而广播的内容是:VOLUME_CHANGED_ACTION,也即"android.media.VOLUME_CHANGED_ACTION";当对音量改变事件有兴趣时,就可以接收这个广播,并做出相应的处理。至此,声音调整的相关流程就分析的差不多了。