Android 耳机插拔流程源码跟踪浅析

Android 开发过程中，使用耳机控制拍照，控制音乐播放，控制打电话等，线控再到蓝牙控... 耳机也在不断升级，耳机插拔的程序这一块也在不断完善。因此，在定制开发过程中，阅读这部分流程代码是必修的功课了，至少首先的要搞清楚程序走的线路流程。下面结合我在实际工作过程中遇到的bug，需求定制等做个简单的总结。

第一节，插拔耳机时，事件上报

抓取事件命令：
查看有哪些事件可以get

PS C:\Users\xxxx> adb shell getevent -l
add device 1: /dev/input/event11
name:     "comp"
add device 2: /dev/input/event10
name:     "accel"
add device 3: /dev/input/event9
name:     "gyro"
add device 4: /dev/input/event0
name:     "Power Button"
add device 5: /dev/input/event5
name:     "Video Bus"
add device 6: /dev/input/event8
name:     "baytrailaudio Intel MID Audio Jack"
add device 7: /dev/input/event6
name:     "gpio-lesskey"
add device 8: /dev/input/event7
name:     "dollar_cove_power_button"
add device 9: /dev/input/event3
name:     "jsa1212_als"
add device 10: /dev/input/event2
name:     "jsa1212_ps"
add device 11: /dev/input/event1
name:     "sx9500"
add device 12: /dev/input/event4
name:     "goodix_ts"

event8正式我们想要查看的event。

add device 6: /dev/input/event8
name:     "baytrailaudio Intel MID Audio Jack"

下面我们开始get event8 详细信息，下面事件信息分别是拔出和插入耳机时事件信息。

SW_MICROPHONE_INSERT

带mic的耳机。

PS C:\Users\xxxx> adb shell getevent -l  /dev/input/event8
EV_SW        SW_HEADPHONE_INSERT  00000000
EV_SW        SW_MICROPHONE_INSERT 00000000
EV_SYN       SYN_REPORT           00000000
EV_SW        SW_HEADPHONE_INSERT  00000001
EV_SW        SW_MICROPHONE_INSERT 00000001
EV_SYN       SYN_REPORT           00000000

从上面的输出数据中我们可以看到，插入耳机上报1，拔出是0。
另外，我们可以从get parameter命令看到当前信息(注：这个命令是特别方案才有，取决于芯片商)

PS C:\Users\xxxx> adb shell parameter status
...
Last Applied [Pending] Configurations:
======================================
OutputDevice.Private.Selected: WiredSpeakers [<none>]
IHF.SDRC: Enabled [<none>]
InputDevice.Selected: HeadsetMic [<none>]
OutputDevice.Selected: Multimedia.IHF.Headset [<none>]
IHF.StereoEq: Enabled [<none>]
Headset.Selected: Digital [<none>]
Voip.Tuning: Default [<none>]
Calibration: Default [<none>]
LPE_Mixer: Default [<none>]
Audio.voice: Default [<none>]
...

InputDevice.Selected

 ，

OutputDevice.Selected

等我们可以看到是使
4000
用耳机状态。拔掉耳机，我们看一下具体的parameter信息：

Last Applied [Pending] Configurations:
======================================
OutputDevice.Private.Selected: WiredSpeakers [<none>]
IHF.SDRC: Enabled [<none>]
InputDevice.Selected: VoiceRecgnition.FrontMic [<none>]
OutputDevice.Selected: Multimedia.IHF [<none>]
IHF.StereoEq: Enabled [<none>]
Headset.Selected: Digital [<none>]
Voip.Tuning: Default [<none>]
Calibration: Default [<none>]
LPE_Mixer: Default [<none>]

此时相关参数发生了变化：

InputDevice.Selected

，

OutputDevice.Selected

 等已经发生了变化。

第二节，插入拔出framework部分相关源码流程分析

涉及到的类文件
InputManagerService.java

./framework/base/services/core/java/com/android/server/input/InputManagerService.java

*WiredAccessoryManager.java.

./framework/base/services/core/java/com/android/server/WiredAccessoryManager.java
config.xml

./framework/base/core/res/res/values/config.xml
SystemServer.java

./framework/base/services/java/com/android/server/SystemServer.java
AudioManager.java

./base/media/java/android/media/AudioManager.java
AudioService.java

./base/media/java/android/media/AudioService.java

UEvent和InputEvent的选择

这两个的切换主要是通过设置属性来的。该属性开关位于config.xml中：

<!-- When true use the linux /dev/input/event subsystem to detect the switch changes
on the headphone/microphone jack. When false use the older uevent framework. -->
<bool name="config_useDevInputEventForAudioJack">false</bool>

从注释里面我们可以看到设置为true，选择/dev/input/event ，设置为false 选择uevent 来控制事件的上报。

在InputManagerService.java 构造方法中，config_useDevInputEventForAudioJack的值初始化mUseDevInputEventForAudioJack 决定采用哪种方式。

public InputManagerService(Context context) {
this.mContext = context;
this.mHandler = new InputManagerHandler(DisplayThread.get().getLooper());

//config_useDevInputEventForAudioJack
mUseDevInputEventForAudioJack =
context.getResources().getBoolean(R.bool.config_useDevInputEventForAudioJack);
Slog.i(TAG, "Initializing input manager, mUseDevInputEventForAudioJack="
+ mUseDevInputEventForAudioJack);
mPtr = nativeInit(this, mContext, mHandler.getLooper().getQueue());

LocalServices.addService(InputManagerInternal.class, new LocalService());
}

插入耳机底层kernal事件上报后(注:这段过程需要研究)，转到

InputManagerService.java

中的

notifySwitch

方法中。

接下来我们先看

notifySwitch

方法：

// Native callback.
private void notifySwitch(long whenNanos, int switchValues, int switchMask) {

... 因为当前我们只看耳机插拔的模式，因此，其他的先排除。
if (mUseDevInputEventForAudioJack && (switchMask & SW_JACK_BITS) != 0) {
mWiredAccessoryCallbacks.notifyWiredAccessoryChanged(whenNanos, switchValues,
switchMask);
}
}

接下来是走到

mWiredAccessoryCallbacks

 回调中。

有个疑问：

mWiredAccessoryCallbacks

是什么呢？ 先看看回调*

接下来我们先顺藤摸瓜从这个callBack的声明初始化开始，找到目标。

WiredAccessoryCallbacks

接口的声明，它在

WiredAccessoryManager.java

类的内部，接口有两个方法，一个是

notifyWiredAccessoryChanged

另外一个是

systemReady

 。

/**
* Callback interface implemented by WiredAccessoryObserver.
*/
public interface WiredAccessoryCallbacks {
public void notifyWiredAccessoryChanged(long whenNanos, int switchValues, int switchMask);
public void systemReady();
}

再看何时将它初始化：

public void setWindowManagerCallbacks(WindowManagerCallbacks callbacks) {
mWindowManagerCallbacks = callbacks;
}

setWindowManagerCallbacks

的调用在

SystemServer.java

中，也就是

InputManagerService

被创建的时候。

接下来转到SystemServer.java中：

inputManager = new InputManagerService(context);
wm = WindowManagerService.main(context, inputManager,
mFactoryTestMode != FactoryTest.FACTORY_TEST_LOW_LEVEL/* always false*/,
!mFirstBoot/* always true*/,mOnlyCore/* always false*/);
ServiceManager.addService(Context.WINDOW_SERVICE, wm);
//register the inputManagerService to ServiceManager
ServiceManager.addService(Context.INPUT_SERVICE, inputManager);
...
if (!disableMedia) {
try {
Slog.i(TAG, "Wired Accessory Manager");
// Listen for wired headset changes
inputManager.setWiredAccessoryCallbacks(
new WiredAccessoryManager(context, inputManager));
} catch (Throwable e) {
reportWtf("starting WiredAccessoryManager", e);
16b9c

}
}

从上面的代码可以看到

WiredAccessoryManager

对象直接被注册为callBack 因此，

mWiredAccessoryCallbacks.notifyWiredAccessoryChanged

直接将后面的任务交给了

WiredAccessoryManager

类。

WiredAccessoryManager.java

notifyWiredAccessoryChanged方法：

@Override
public void notifyWiredAccessoryChanged(long whenNanos, int switchValues, int switchMask) {
synchronized (mLock) {
int headset;
mSwitchValues = (mSwitchValues & ~switchMask) | switchValues;
switch (mSwitchValues &
(SW_HEADPHONE_INSERT_BIT | SW_MICROPHONE_INSERT_BIT | SW_LINEOUT_INSERT_BIT)) {
case 0:
headset = 0;
break;

case SW_HEADPHONE_INSERT_BIT:
headset = BIT_HEADSET_NO_MIC;
break;

case SW_LINEOUT_INSERT_BIT:
headset = BIT_LINEOUT;
break;

case SW_HEADPHONE_INSERT_BIT | SW_MICROPHONE_INSERT_BIT:
headset = BIT_HEADSET;
break;

case SW_MICROPHONE_INSERT_BIT:
headset = BIT_HEADSET;
break;

default:
headset = 0;
break;
}
//上面的switch 语句是看哪种耳机，带mic否？
updateLocked(NAME_H2W,
(mHeadsetState & ~(BIT_HEADSET | BIT_HEADSET_NO_MIC | BIT_LINEOUT)) | headset);
}
}

接着转到updateLocked方法,该方法作用是check当前模式是否变化。也就是是否发生耳机拔出了或者插入了(0->1;1->0的变化)。state无变化则不会继续处理。
疑问：这里的BIT_USB_HEADSET_ANLG和BIT_USB_HEADSET_DGTL是什么?

/**
* Compare the existing headset state with the new state and pass along accordingly. Note
* that this only supports a single headset at a time. Inserting both a usb and jacked headset
* results in support for the last one plugged in. Similarly, unplugging either is seen as
* unplugging all.
*
* @param newName One of the NAME_xxx variables defined above.
* @param newState 0 or one of the BIT_xxx variables defined above.
*/
private void updateLocked(String newName, int newState) {
// Retain only relevant bits
int headsetState = newState & SUPPORTED_HEADSETS;
int usb_headset_anlg = headsetState & BIT_USB_HEADSET_ANLG;
int usb_headset_dgtl = headsetState & BIT_USB_HEADSET_DGTL;
int h2w_headset = headsetState & (BIT_HEADSET | BIT_HEADSET_NO_MIC | BIT_LINEOUT);
boolean h2wStateChange = true;
boolean usbStateChange = true;

//fulairy add: check the state changed or not mHeadsetState is old state and headsetState is new state
if (mHeadsetState == headsetState) {
Log.e(TAG, "No state change.");
return;
}

// reject all suspect transitions: only accept state changes from:
// - a: 0 headset to 1 headset
// - b: 1 headset to 0 headset
if (h2w_headset == (BIT_HEADSET | BIT_HEADSET_NO_MIC | BIT_LINEOUT)) {
Log.e(TAG, "Invalid combination, unsetting h2w flag");
h2wStateChange = false;
}
// - c: 0 usb headset to 1 usb headset
// - d: 1 usb headset to 0 usb headset
if (usb_headset_anlg == BIT_USB_HEADSET_ANLG && usb_headset_dgtl == BIT_USB_HEADSET_DGTL) {
Log.e(TAG, "Invalid combination, unsetting usb flag");
usbStateChange = false;
}
//flairy add : h2wStateChange and usbStateChange all not changed .
if (!h2wStateChange && !usbStateChange) {
Log.e(TAG, "invalid transition, returning ...");
return;
}

mWakeLock.acquire();
//flairy add : yeah ,you changed pls mHandler deal with it .
Message msg = mHandler.obtainMessage(MSG_NEW_DEVICE_STATE/*what*/, headsetState/*arg0*/, //headsetState 新状态
mHeadsetState/*arg1*/, newName/*obj*/);//mHeadsetState 旧的状态,newName name of the headset .
mHandler.sendMessage(msg);

mHeadsetState = headsetState;// update the status .
}

接下来mHandler处理：

private final Handler mHandler = new Handler(Looper.myLooper(), null, true) {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MSG_NEW_DEVICE_STATE:
setDevicesState(msg.arg1, msg.arg2, (String)msg.obj);
mWakeLock.release();
break;
...
}
}
};

//这个方法挺有意思...就是没看明白 :(
private void setDevicesState(
int headsetState, int prevHeadsetState, String headsetName) {
synchronized (mLock) {
int allHeadsets = SUPPORTED_HEADSETS;
for (int curHeadset = 1; allHeadsets != 0; curHeadset <<= 1) {
if ((curHeadset & allHeadsets) != 0) {
setDeviceStateLocked(curHeadset, headsetState, prevHeadsetState, headsetName);
allHeadsets &= ~curHeadset;
}
}
}
}

private void setDeviceStateLocked(int headset,
int headsetState, int prevHeadsetState, String headsetName) {
if ((headsetState & headset) != (prevHeadsetState & headset)) {
int outDevice = 0;
int inDevice = 0;
int state;
//important:  state set start
if ((headsetState & headset) != 0) {
state = 1;
} else {
state = 0;
}
// important : state set end

if (headset == BIT_HEADSET) {
outDevice = AudioManager.DEVICE_OUT_WIRED_HEADSET;
inDevice = AudioManager.DEVICE_IN_WIRED_HEADSET;
} else if (headset == BIT_HEADSET_NO_MIC){
outDevice = AudioManager.DEVICE_OUT_WIRED_HEADPHONE;
} else if (headset == BIT_LINEOUT){
outDevice = AudioManager.DEVICE_OUT_LINE;
} else if (headset == BIT_USB_HEADSET_ANLG) {
outDevice = AudioManager.DEVICE_OUT_ANLG_DOCK_HEADSET;
} else if (headset == BIT_USB_HEADSET_DGTL) {
outDevice = AudioManager.DEVICE_OUT_DGTL_DOCK_HEADSET;
} else if (headset == BIT_HDMI_AUDIO) {
outDevice = AudioManager.DEVICE_OUT_HDMI;
} else {
Slog.e(TAG, "setDeviceState() invalid headset type: "+headset);
return;
}
...

//update the out device and in device .
if (outDevice != 0) {
mAudioManager.setWiredDeviceConnectionState(outDevice, state, headsetName);
}
//这里我们仅仅看in device.
if (inDevice != 0) {
mAudioManager.setWiredDeviceConnectionState(inDevice, state, headsetName);
}
}
}

接下来的流程就交给了

AudioManager

，从代码看实际上真正的处理这是AudioService

IAudioService service = getService();
...
service.setWiredDeviceConnectionState(device, state, name);

因此我们跳过AudioManager.java直接从AduioService.java看。

setWiredDeviceConnectionState--> queueMsgUnderWakeLock-->sendMsg--> ...
从源代码看到这里，你可以发现AudioService是个非常重要的角色，因此它里面的控制逻辑很多建议多多理解。

接下来我们直接从handler处理消息开始。因为我们只搞清楚headset处理的这条线。

...
case MSG_SET_WIRED_DEVICE_CONNECTION_STATE:
onSetWiredDeviceConnectionState(msg.arg1, msg.arg2, (String)msg.obj);
mAudioEventWakeLock.release();
break;
...

private void onSetWiredDeviceConnectionState(int device, int state, String name)
{
synchronized (mConnectedDevices) {
//state==0 ===> the device is disconnected.
...  //ignore BluetoothA2dp Device.
...
handleDeviceConnection((state == 1)/*FULAIRY ADD :true if connected , false if disconnected */, device, (isUsb ? name : ""/* FuLaiRy add :that's why we get empty string when we use common headset.*/));
... // other conditions we also ignore
// FuLAIRY ADD :Send broadcast ...
if (!isUsb && (device != AudioSystem.DEVICE_IN_WIRED_HEADSET)) {
sendDeviceConnectionIntent(device, state, name);
}
}
}

onSetWiredDeviceConnectionState

方法中我们忽略其他一些情况的处理，看最主要的两个：
一个是

handleDeviceConnection

,另外一个是

sendDeviceConnectionIntent

。因此，下面我们主要看着两个方法。

handleDeviceConnection

private boolean handleDeviceConnection(boolean connected, int device, String params) {
synchronized (mConnectedDevices) {
//Fulairy: mConnectedDevices is a hashMap :
//private final HashMap <Integer, String> mConnectedDevices = new HashMap <Integer, String>();

// the if means that if key and values are all equal,indicate the same device has been connected .
boolean isConnected = (mConnectedDevices.containsKey(device) &&
(params.isEmpty() || mConnectedDevices.get(device).equals(params)));

if (isConnected && !connected) {
//断开
AudioSystem.setDeviceConnectionState(device,
AudioSystem.DEVICE_STATE_UNAVAILABLE,
mConnectedDevices.get(device));
mConnectedDevices.remove(device);
return true;
} else if (!isConnected && connected) {
//连接
//接下来的处理在JNI方法
AudioSystem.setDeviceConnectionState(device,
AudioSystem.DEVICE_STATE_AVAILABLE,
params);
mConnectedDevices.put(new Integer(device), params);
return true;
}
}
return false;
}
...

JNI部分放到后面补充。

sendDeviceConnectionIntent

从这个方法，可以看到intent耳机插拔的广播我们可以在app层通过监听

ACTION_HEADSET_PLUG

。
intent携带了，当前最新状态state ,name以及microphone(耳机是否带麦)。可以从自带音乐播放器看看。

private void sendDeviceConnectionIntent(int device, int state, String name)
{
Intent intent = new Intent();

intent.putExtra("state", state);
intent.putExtra("name", name);
intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);

int connType = 0;

if (device == AudioSystem.DEVICE_OUT_WIRED_HEADSET) {
connType = AudioRoutesInfo.MAIN_HEADSET;
intent.setAction(Intent.ACTION_HEADSET_PLUG);
intent.putExtra("microphone", 1);
} else if (device == AudioSystem.DEVICE_OUT_WIRED_HEADPHONE ||
device == AudioSystem.DEVICE_OUT_LINE) {
/*do apps care about line-out vs headphones?*/
connType = AudioRoutesInfo.MAIN_HEADPHONES;
intent.setAction(Intent.ACTION_HEADSET_PLUG);
intent.putExtra("microphone", 0);
} ...
... 割舍了也很重要的一些其他逻辑处理。
try {
ActivityManagerNative.broadcastStickyIntent(intent, null, UserHandle.USER_ALL); // 后面的流程就不继续跟了，这个是通用，单独分出一条线比较好，check里面是如何运作的。
} finally ...
}

说到这里我们不得不提一下，插入与拔出耳机通知栏耳机图标的显示与消失。

第三节，插拔耳机，通知栏图标的显示与消失。

在原生应用中，搜索

ACTION_HEADSET_PLUG

我们是搜索不到的。因为没有做处理。下面我们自己添加。
涉及到的文件

PhoneStatusBarPolicy.java

frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone

添加广播注册

//FuLairy add: HeadSet start
filter.addAction(Intent.ACTION_HEADSET_PLUG) ;
//FuLairy add: HeadSet start
mContext.registerReceiver(mIntentReceiver, filter, null, mHandler);

// FuLaiRy add Headset start
mService.setIcon(SLOT_HEADSET,  R.drawable.stat_sys_tty_mode, 0, null);
mService.setIconVisibility(SLOT_HEADSET, false);
// FuLaiRy add Headset end

新增update方法

//FuLairy add: HeadSet start

public final void updateHeadSet(intent){

final int state = intent.getIntExtra("state",0/*default*/) ;
final String name = intent.getStringExtra("name",""/*this always be empty string*/) ;
final int microPhone =intent.getIntExtra("microphone",0/*default*/) ;

switch(state){

case 0:
//disconnected
String contentDescription = mContext.getString(R.string.headset_disconnected);
mService.setIcon(SLOT_HEADSET, R.drawable.head_set_disconnected_icon, 0, contentDescription);
mService.setIconVisibility(SLOT_HEADSET, false);
break;
case 1:
//connected
String contentDescription = mContext.getString(R.string.headset_connected);
if(microPhone==1){

mService.setIcon(SLOT_HEADSET, R.drawable.head_set_connected_icon_microphone, 0, contentDescription);
mService.setIconVisibility(SLOT_HEADSET, true);
}else if(microPhone==0){

mService.setIcon(SLOT_HEADSET, R.drawable.head_set_connected_icon_nomicrophone, 0, contentDescription);
mService.setIconVisibility(SLOT_HEADSET, true);
}
break;
default:
mService.setIconVisibility(SLOT_HEADSET, false);
}}//FuLairy add: HeadSet end

core/res/res/values/config.xml中添加：
<item><xliff:g id="id">headset</xliff:g></item>

大概就这个思路，由于条件限制了，不然可以完整提供一下patch。流程清楚后，修改就快的多。