漸進式的:
AudioManager am = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
public void adjustStreamVolume (int streamType, int direction, int flags);
am.adjustStreamVolume (AudioManager.STREAM_MUSIC, AudioManager.ADJUST_RAISE, AudioManager.FLAG_SHOW_UI);
adjustStreamVolume 最終調用的是這個方法,這個方法裏有三個參數,分析如下:
第一個,streamType是需要調整音量的類型:
STREAM_ALARM 警報
STREAM_MUSIC 音樂回放即媒體音量
STREAM_NOTIFICATION 窗口頂部狀態欄Notification,
STREAM_RING 鈴聲
STREAM_SYSTEM 系統
STREAM_VOICE_CALL 通話
STREAM_DTMF 電話撥號音頻
第二個direction,是調整的方向,增加或減少:
ADJUST_LOWER 降低音量
ADJUST_RAISE 升高音量
ADJUST_SAME 保持不變,貌似只是顯示當前音量大小。
第三個flags是一些附加參數,只介紹兩個常用的
FLAG_PLAY_SOUND 調整音量時播放聲音
FLAG_SHOW_UI 調整時顯示音量條,就是按音量鍵出現的那個
0 表示什麼也沒有
下面看下adjustStreamVolume 的具體調用:
public void adjustStreamVolume(int streamType, int direction, int flags) {
IAudioService service = getService();
try {
service.adjustStreamVolume(streamType, direction, flags);
} catch (RemoteException e) {
Log.e(TAG, "Dead object in adjustStreamVolume", e);
}
}
從代碼裏面可以看到,這裏是調用的AudioService裏面的adjustStreamVolume()方法,而AudioService的實現文件是:AudioService.java,其方法實現如下:
public void adjustStreamVolume(int streamType, int direction, int flags) {
ensureValidDirection(direction); //數據正確性檢查
ensureValidStreamType(streamType); //數據正確性檢查
。
。
。
// If stream is muted, adjust last audible index only
int index; //局部變量,保存調整後的音量狀態
//進行實際的音量調整,在mAudioHandler裏面進行。
if (streamState.muteCount() != 0) {
if (adjustVolume) {
streamState.adjustLastAudibleIndex(direction);
// Post a persist volume msg
sendMsg(mAudioHandler, MSG_PERSIST_VOLUME, streamType,
SENDMSG_REPLACE, 0, 1, streamState, PERSIST_DELAY);
}
index = streamState.mLastAudibleIndex;
} else {
if (adjustVolume && streamState.adjustIndex(direction)) {
// Post message to set system volume (it in turn will post a message
// to persist). Do not change volume if stream is muted.
sendMsg(mAudioHandler, MSG_SET_SYSTEM_VOLUME, STREAM_VOLUME_ALIAS[streamType], SENDMSG_NOOP, 0, 0,
streamState, 0);
}
index = streamState.mIndex;
}
// UI //畫UI,即調整音量時出現的那個ProgressBar
mVolumePanel.postVolumeChanged(streamType, flags);
// Broadcast Intent //發送廣播,廣播音量有改變的系統事件
sendVolumeUpdate(streamType, oldIndex, index);
}
下面先來看看畫UI的過程:
跟進VolumePanel,發現這個類是一個handle,在postVolumeChanged()方法裏面有如下代碼:
[java] view plaincopy
public void postVolumeChanged(int streamType, int flags) {
if (hasMessages(MSG_VOLUME_CHANGED)) return;
removeMessages(MSG_FREE_RESOURCES);
obtainMessage(MSG_VOLUME_CHANGED, streamType, flags).sendToTarget();
}
這裏利用了android裏面的消息機制來傳遞消息。對android的消息機制有所瞭解的應該知道,這個sendToTarget()方法實際上最後的Target就是它本身,也就是VolumePanel這個類本身,因此我們去這個Handle的handleMessage()方法裏面查找對於MSG_VOLUME_CHANGED這個類型消息的處理:
[java] view plaincopy
case MSG_VOLUME_CHANGED: {
onVolumeChanged(msg.arg1, msg.arg2);
break;
}
可以看到,後續是在onVolumeChanged()這個方法裏面處理的,其兩個參數分別是streamType和flags,其中streamType是要調整的音量類型,而flags是傳過來的UI類型。onVolumeChanged()方法代碼如下:
[java] view plaincopy
protected void onVolumeChanged(int streamType, int flags) {
if (LOGD) Log.d(TAG, "onVolumeChanged(streamType: " + streamType + ", flags: " + flags + ")");
//根據flags的不同,來做不同的處理
if ((flags & AudioManager.FLAG_SHOW_UI) != 0) {
onShowVolumeChanged(streamType, flags);//UI顯示
}
if ((flags & AudioManager.FLAG_PLAY_SOUND) != 0 && ! mRingIsSilent) {
removeMessages(MSG_PLAY_SOUND);
sendMessageDelayed(obtainMessage(MSG_PLAY_SOUND, streamType, flags), PLAY_SOUND_DELAY);//播放聲音
}
if ((flags & AudioManager.FLAG_REMOVE_SOUND_AND_VIBRATE) != 0) {
removeMessages(MSG_PLAY_SOUND);
removeMessages(MSG_VIBRATE);
onStopSounds();//停止播放聲音和震動
}
removeMessages(MSG_FREE_RESOURCES);
sendMessageDelayed(obtainMessage(MSG_FREE_RESOURCES), FREE_DELAY);
}
通過代碼可以知道,根據傳進去的flags不同,有不同的處理,下面就看看onShowVolumeChanged()方法的處理,也就是ProgressBar的顯示:
[java] view plaincopy
protected void onShowVolumeChanged(int streamType, int flags) {
int index = mAudioService.getStreamVolume(streamType);
int message = UNKNOWN_VOLUME_TEXT;
int additionalMessage = 0;
mRingIsSilent = false;
if (LOGD) {
Log.d(TAG, "onShowVolumeChanged(streamType: " + streamType
+ ", flags: " + flags + "), index: " + index);
}
// get max volume for progress bar
int max = mAudioService.getStreamMaxVolume(streamType);
switch (streamType) {
case AudioManager.STREAM_RING: { //鈴聲的處理
setRingerIcon();
message = RINGTONE_VOLUME_TEXT;
Uri ringuri = RingtoneManager.getActualDefaultRingtoneUri(
mContext, RingtoneManager.TYPE_RINGTONE);
Uri ringTwoUri = RingtoneManager.getActualDefaultRingtoneUri(mContext, RingtoneManager.TYPE_RINGTONE,
PhoneFactory.RAW_PHONE_ID);
if ((ringuri == null) && (ringTwoUri == null)) {
additionalMessage =
//com.android.internal.R.string.volume_music_hint_silent_ringtone_selected;
com.android.internal.R.string.volume_music_hint_sim1_and_sim2_silent_ringtone_selected;
mRingIsSilent = true;
} else if ((ringuri == null) && (ringTwoUri != null)) {
additionalMessage =
com.android.internal.R.string.volume_music_hint_silent_sim1_ringtone_selected;
} else if ((ringuri != null) && (ringTwoUri == null)) {
additionalMessage =
com.android.internal.R.string.volume_music_hint_sim2_silent_ringtone_selected;
}
break;
}
case AudioManager.STREAM_MUSIC: { //音樂聲音的處理
message = MUSIC_VOLUME_TEXT;
if (mAudioManager.isBluetoothA2dpOn()) {
additionalMessage =
com.android.internal.R.string.volume_music_hint_playing_through_bluetooth;
setLargeIcon(com.android.internal.R.drawable.ic_volume_bluetooth_ad2p);
} else {
setSmallIcon(index);
}
break;
}
case AudioManager.STREAM_FM: { //FM聲音的處理
message = FM_VOLUME_TEXT;
setSmallIcon(index);
break;
}
case AudioManager.STREAM_VOICE_CALL: { //通話聲音的處理
/*
* For in-call voice call volume, there is no inaudible volume.
* Rescale the UI control so the progress bar doesn't go all
* the way to zero and don't show the mute icon.
*/
index++;
max++;
message = INCALL_VOLUME_TEXT;
setSmallIcon(index);
break;
}
case AudioManager.STREAM_ALARM: { //鬧鐘聲音的處理
message = ALARM_VOLUME_TEXT;
setSmallIcon(index);
break;
}
case AudioManager.STREAM_NOTIFICATION: { //Notification聲音的處理
message = NOTIFICATION_VOLUME_TEXT;
setSmallIcon(index);
Uri ringuri = RingtoneManager.getActualDefaultRingtoneUri(
mContext, RingtoneManager.TYPE_NOTIFICATION);
if (ringuri == null) {
additionalMessage =
com.android.internal.R.string.volume_music_hint_silent_ringtone_selected;
mRingIsSilent = true;
}
break;
}
case AudioManager.STREAM_BLUETOOTH_SCO: { //藍牙_sco?不知道是什麼東西。。
/*
* For in-call voice call volume, there is no inaudible volume.
* Rescale the UI control so the progress bar doesn't go all
* the way to zero and don't show the mute icon.
*/
index++;
max++;
message = BLUETOOTH_INCALL_VOLUME_TEXT;
setLargeIcon(com.android.internal.R.drawable.ic_volume_bluetooth_in_call);
break;
}
}
String messageString = Resources.getSystem().getString(message); //根據調整的聲音不同,顯示不同的信息
if (!mMessage.getText().equals(messageString)) {
mMessage.setText(messageString);
}
if (additionalMessage == 0) {
mAdditionalMessage.setVisibility(View.GONE);
} else {
mAdditionalMessage.setVisibility(View.VISIBLE);
mAdditionalMessage.setText(Resources.getSystem().getString(additionalMessage));
}
if (max != mLevel.getMax()) {
mLevel.setMax(max);
}
mLevel.setProgress(index); //設置ProgressBar的值
mToast.setView(mView);
mToast.setDuration(Toast.LENGTH_SHORT);
mToast.setGravity(Gravity.TOP, 0, 0);
mToast.show();
// Do a little vibrate if applicable (only when going into vibrate mode)
if ((flags & AudioManager.FLAG_VIBRATE) != 0 &&
mAudioService.isStreamAffectedByRingerMode(streamType) &&
mAudioService.getRingerMode() == AudioManager.RINGER_MODE_VIBRATE &&
mAudioService.shouldVibrate(AudioManager.VIBRATE_TYPE_RINGER)) {
sendMessageDelayed(obtainMessage(MSG_VIBRATE), VIBRATE_DELAY);
}
}
在通話聲音的處理中,有個setSmallIcon()函數,可以看到,這個是根據不同情況選擇ProgressBar上面顯示的圖片的。
[java] view plaincopy
private void setSmallIcon(int index) {
mLargeStreamIcon.setVisibility(View.GONE);
mSmallStreamIcon.setVisibility(View.VISIBLE);
mSmallStreamIcon.setImageResource(index == 0
? com.android.internal.R.drawable.ic_volume_off_small
: com.android.internal.R.drawable.ic_volume_small);
}
View view = mView = inflater.inflate(com.android.internal.R.layout.volume_adjust, null);
mLevel就是顯示的那個ProgressBar,mLevel = (ProgressBar) view.findViewById(com.android.internal.R.id.level);
從這裏我們可以看到,聲音調整顯示的佈局文件是volume_adjust.xml,如果想自己對聲音顯示的佈局進行調整的話,就可以自己手動修改這個佈局文件,達到自己想要的效果了。
到這裏就把聲音調整的UI顯示過程分析完了,下面接着來分析聲音調整廣播發送sendVolumeUpdate():
[java] view plaincopy
private void sendVolumeUpdate(int streamType, int oldIndex, int index) {
oldIndex = (oldIndex + 5) / 10;
index = (index + 5) / 10;
Intent intent = new Intent(AudioManager.VOLUME_CHANGED_ACTION);
intent.putExtra(AudioManager.EXTRA_VOLUME_STREAM_TYPE, streamType);
intent.putExtra(AudioManager.EXTRA_VOLUME_STREAM_VALUE, index);
intent.putExtra(AudioManager.EXTRA_PREV_VOLUME_STREAM_VALUE, oldIndex);
mContext.sendBroadcast(intent);
}
可以看到,這裏發送了一個廣播,而廣播的內容是:VOLUME_CHANGED_ACTION,也即"android.media.VOLUME_CHANGED_ACTION";當對音量改變事件有興趣時,就可以接收這個廣播,並做出相應的處理。至此,聲音調整的相關流程就分析的差不多了。
直接設置音量值:
AudioManager audioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
audioManager.setStreamVolume(AudioManager.STREAM_SYSTEM, arg1, 0);
audioManager.setStreamVolume(3, arg1, 0);// 3 代表 AudioManager.STREAM_MUSIC
這個方法主要用在有seekbar,調節音量的形式上。在設置->聲音->音量 就是這種形式。
但是這個方法有個缺點,就是在播放音樂的時候使用這種方式連續調整音量,會倒是音樂聲音出現斷斷續續的情況。