1.蓝牙耳机接听电话
这个就对应HFP(Hands-freeProfile)，Free your Hand，蓝牙的初衷之一。先来看这个功能的场景，手机来电，手机与蓝牙耳机已连接，这时会优先触发蓝牙接听电话的代码流程，起步代码在phone\src\com\android\phone\nCallScreen.java的connectBluetoothAudio() /disconnectBluetoothAudio()，只看连接部分好了，注意下面代码里的注释，
void connectBluetoothAudio() {
if (VDBG) log("connectBluetoothAudio()...");
if (mBluetoothHeadset != null) {
// TODO(BT) check return
mBluetoothHeadset.connectAudio();
}
// Watch out: The bluetooth connection doesn't happen instantly;
// the connectAudio() call returns instantly but does its real
// work in another thread. The mBluetoothConnectionPending flag
// is just a little trickery to ensure that the onscreen UI updates
// instantly. (See isBluetoothAudioConnectedOrPending() above.)
mBluetoothConnectionPending = true;
mBluetoothConnectionRequestTime = SystemClock.elapsedRealtime();
接下来就跳到蓝牙应用的管辖范围，代码在packages/apps/Bluetooth/src/com/android/bluetooth/hfp/HeadsetService.java，[java] view plaincopy
public boolean connectAudio() {
HeadsetService service = getService();
if (service == null) return false;
return service.connectAudio();
}
很明显下一个目标是HeadsetService，直接看具体实现，这部分代码跳转都比较清晰，下面代码会先判断当前状态是否正确，关于HeadsetStateMachine几个状态可以参持这个/packages/apps/Bluetooth/src/com/android/bluetooth/hfp/HeadsetStateMachine.java的最前的代码注释。[java] view plaincopy
boolean connectAudio() {
// TODO(BT) BLUETOOTH or BLUETOOTH_ADMIN permission
enforceCallingOrSelfPermission(BLUETOOTH_PERM, "Need BLUETOOTH permission");
if (!mStateMachine.isConnected()) {
return false;
}
if (mStateMachine.isAudioOn()) {
return false;
}
mStateMachine.sendMessage(HeadsetStateMachine.CONNECT_AUDIO);
return true;
}
走进HeadsetStateMachine状态机，找到CONNECT_AUDIO分支，就看带Native的方法connectAudioNative(getByteAddress(mCurrentDevice))；[java] view plaincopy
static jboolean connectAudioNative(JNIEnv *env, jobject object, jbyteArray address) {
jbyte *addr;
bt_status_t status;
if (!sBluetoothHfpInterface) return JNI_FALSE;
addr = env->GetByteArrayElements(address, NULL);
if (!addr) {
jniThrowIOException(env, EINVAL);
return JNI_FALSE;
}
//连接在这里
if ( (status = sBluetoothHfpInterface->connect_audio((bt_bdaddr_t *)addr)) !=
BT_STATUS_SUCCESS) {
ALOGE("Failed HF audio connection, status: %d", status);
}
env->ReleaseByteArrayElements(address, addr, 0);
return (status == BT_STATUS_SUCCESS) ? JNI_TRUE : JNI_FALSE;
}
上面代码还可以进一步跟到下面/external/bluetooth/bluedroid/btif/src/btif_hf.c，到了这里其实流程已经结束了，对于这里消息流转估计要放到以后再写了[java] view plaincopy
static bt_status_t connect_audio( bt_bdaddr_t *bd_addr )
{
CHECK_BTHF_INIT();
if (is_connected(bd_addr))
{
BTA_AgAudioOpen(btif_hf_cb.handle);
btif_transfer_context(btif_in_hf_generic_evt, BTIF_HFP_CB_AUDIO_CONNECTING,
(char *)bd_addr, sizeof(bt_bdaddr_t), NULL);
return BT_STATUS_SUCCESS;
}
return BT_STATUS_FAIL;
}
2.在蓝牙列表中连接蓝牙耳机
A2dp的连接过程，在蓝牙搜索结果列表连接一个蓝牙耳机，既然是从设备列表开始，所以起步代码自然是这个了
DevicePickerFragment.java (settings\src\com\android\settings\bluetooth) 3884 2013-6-26
void onClicked() {
int bondState = mCachedDevice.getBondState();
if (mCachedDevice.isConnected()) {
askDisconnect();
} else if (bondState == BluetoothDevice.BOND_BONDED) {
mCachedDevice.connect(true);
} .......
}
void connect(boolean connectAllProfiles) {
if (!ensurePaired()) { //要先确保配对
return;
}
mConnectAttempted = SystemClock.elapsedRealtime();
connectWithoutResettingTimer(connectAllProfiles);//没别的了，只能看到这里
}
代码路径这里packages/apps/Settings/src/com/android/settings/bluetooth/CachedBluetoothDevice.java，具体代码看下面[java] view plaincopy
// Try to initialize the profiles if they were not.
...........
// Reset the only-show-one-error-dialog tracking variable
mIsConnectingErrorPossible = true;
int preferredProfiles = 0;
for (LocalBluetoothProfile profile : mProfiles) {
if (connectAllProfiles ? profile.isConnectable() : profile.isAutoConnectable()) {
if (profile.isPreferred(mDevice)) {
++preferredProfiles;
connectInt(profile);//连接在这里，
}
}
}
.............
connectInt的实现很简单，直接跳过看里面的profile.connect(mDevice)，这里的profile是指A2dpProfile，所以connet()方法的具体实现在[java] view plaincopy
public boolean connect(BluetoothDevice device) {
if (mService == null) return false;
List sinks = getConnectedDevices();
if (sinks != null) {
for (BluetoothDevice sink : sinks) {
mService.disconnect(sink);
}}
return mService.connect(device);
}
下面是 BluetoothA2dp.java (frameworks\base\core\java\android\bluetooth) ，为什么是这样看下这个private BluetoothA2dp mService;就知道了[java] view plaincopy
public boolean connect(BluetoothDevice device) {
if (mService != null && isEnabled() &&
isValidDevice(device)) {
try {
return mService.connect(device);
} catch (RemoteException e) {
Log.e(TAG, "Stack:" + Log.getStackTraceString(new Throwable()));
return false;
}
}...........
return false;
Binder跳转
public boolean connect(BluetoothDevice device) {
A2dpService service = getService();
if (service == null) return false;
return service.connect(device);
}
}
之后的跳转和第一部分蓝牙接听电话跳转过程类似，就不重复了，最后会来到packages/apps/Bluetooth/jni/com_android_bluetooth_a2dp.cpp的connectA2dpNative，同样到下面的代码，我们能看到的开放的代码也就是这些，再下面要看vendor的具体实现了。[java] view plaincopy
static jboolean connectA2dpNative(JNIEnv *env, jobject object, jbyteArray address) {
jbyte *addr;
bt_bdaddr_t * btAddr;
bt_status_t status;
ALOGI("%s: sBluetoothA2dpInterface: %p", __FUNCTION__, sBluetoothA2dpInterface);
if (!sBluetoothA2dpInterface) return JNI_FALSE;
addr = env->GetByteArrayElements(address, NULL);
btAddr = (bt_bdaddr_t *) addr;
if (!addr) {
jniThrowIOException(env, EINVAL);
return JNI_FALSE;
}
if ((status = sBluetoothA2dpInterface->connect((bt_bdaddr_t *)addr)) != BT_STATUS_SUCCESS) {
ALOGE("Failed HF connection, status: %d", status);
}
env->ReleaseByteArrayElements(address, addr, 0);
return (status == BT_STATUS_SUCCESS) ? JNI_TRUE : JNI_FALSE;