4.3 android bluetooth hfp分析
所有程序执行的代码都是有入口的,在这里我们暂时分析一种情景,蓝牙打开着,蓝牙耳机连接。
在设置界面点击蓝牙耳机操作:
packages/apps/Settings/src/com/android/settings/bluetooth/BluetoothDevicePreference.java
- void onClicked() {
- int bondState = mCachedDevice.getBondState();
- if (mCachedDevice.isConnected()) {
- askDisconnect();
- } else if (bondState == BluetoothDevice.BOND_BONDED) { //已经配对,但是未连接
- <span style="color:#ff0000;">mCachedDevice.connect(true);</span>
- } else if (bondState == BluetoothDevice.BOND_NONE) { //没有配对
- <span style="color:#ff0000;">pair();</span>
- }
- }
mCachedDevice.connect(true);方法会直接调用CachedBluetoothDevice.java的connect的方法。
packages/apps/Settings/src/com/android/settings/bluetooth/CachedBluetoothDevice.java
- void connect(boolean connectAllProfiles) {
- if (!ensurePaired()) { //配对处理暂时不关注
- return;
- }
- mConnectAttempted = SystemClock.elapsedRealtime();
- connectWithoutResettingTimer(connectAllProfiles);
- }
代码执行到connectWithoutResettingTimer,注释就不粘贴了。
- private void connectWithoutResettingTimer(boolean connectAllProfiles) {
- ......
- // 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);
- }
- }
- }
- if (DEBUG) Log.d(TAG, "Preferred profiles = " + preferredProfiles);
- if (preferredProfiles == 0) {
- connectAutoConnectableProfiles();
- }
- }
不同的协议实现类,继承于LocalBluetoothProfile,以HeadsetProfile为例。
- synchronized void connectInt(LocalBluetoothProfile profile) {
- if (!ensurePaired()) {
- return;
- }
- if (<span style="color:#ff0000;">profile.connect(mDevice)</span>) {
- if (Utils.D) {
- Log.d(TAG, "Command sent successfully:CONNECT " + describe(profile));
- }
- return;
- }
- Log.i(TAG, "Failed to connect " + profile.toString() + " to " + mName);
- }
这个方法中,profile.connnect(),直接调用 HeadsetProfile的connnect(),其实headset/handsfree 是共用同一个service。
packages/apps/Settings/src/com/android/settings/bluetooth/HeadsetProfile.java
- public boolean connect(BluetoothDevice device) {
- if (mService == null) return false;
- List<BluetoothDevice> sinks = mService.getConnectedDevices();
- if (sinks != null) {//断开所有连接
- for (BluetoothDevice sink : sinks) {
- mService.disconnect(sink);
- }
- }
- return mService.connect(device);
- }
mService.connect 直接进入framwork层,调用Bluetooth Headset server的api。
frameworks/base/core/java/android/bluetooth/BluetoothHeadset.java
- public boolean connect(BluetoothDevice device) {
- if (DBG) log("connect(" + device + ")");
- if (mService != null && isEnabled() &&
- isValidDevice(device)) {
- try {
- return mService.connect(device);
- } catch (RemoteException e) {
- Log.e(TAG, Log.getStackTraceString(new Throwable()));
- return false;
- }
- }
- if (mService == null) Log.w(TAG, "Proxy not attached to service");
- return false;
- }
framework 中转了一下,利用Binder机制再次进入Bluetooth模块。
frameworks/base/core/java/android/bluetooth/IBluetoothHeadset.aidl,实现类是
packages/apps/Bluetooth/src/com/android/bluetooth/hfp/HeadsetService.java
注意顺序:Setting->framewrok->Bluetooth
- public boolean connect(BluetoothDevice device) {
- HeadsetService service = getService();
- if (service == null) return false;
- return service.connect(device);
- }
IBluetoothHeadset.Sub仅仅是一个连接,什么都不做直接进入HeadsetService.java的connect 方法。
- public boolean connect(BluetoothDevice device) {
- enforceCallingOrSelfPermission(BLUETOOTH_ADMIN_PERM,
- "Need BLUETOOTH ADMIN permission");
- if (getPriority(device) == BluetoothProfile.PRIORITY_OFF) {
- return false;
- }
- int connectionState = mStateMachine.getConnectionState(device);
- if (connectionState == BluetoothProfile.STATE_CONNECTED ||
- connectionState == BluetoothProfile.STATE_CONNECTING) {
- return false;
- }
- mStateMachine.sendMessage(HeadsetStateMachine.CONNECT, device);//万恶的状态机开始工作
- return true;
- }
很讨厌android状态机,感觉把java搞成了非面向对象,进入状态机代码实现:
packages/apps/Bluetooth/src/com/android/bluetooth/hfp/HeadsetStateMachine.java
记住当前为 未连接状态,所以应该进入 Disconnected的状态,Disconnected的processMessage方法中:
- switch(message.what) {
- case CONNECT:
- BluetoothDevice device = (BluetoothDevice) message.obj;
- broadcastConnectionState(device, BluetoothProfile.STATE_CONNECTING,
- BluetoothProfile.STATE_DISCONNECTED);
- if (!<span style="color:#ff0000;">connectHfpNative(getByteAddress(device)) </span>) {
- broadcastConnectionState(device, BluetoothProfile.STATE_DISCONNECTED,
- BluetoothProfile.STATE_CONNECTING);
- break;
- }
- synchronized (HeadsetStateMachine.this) {
- mTargetDevice = device;
- transitionTo(mPending);
- }
connectHfpNative 连接,jni 方法 简单了。
packages\apps\bluetooth\jni\Com_android_bluetooth_hfp.cpp
- {"connectHfpNative", "([B)Z", (void *) connectHfpNative},
- static jboolean connectHfpNative(JNIEnv *env, jobject object, jbyteArray address) {
- jbyte *addr;
- bt_status_t status;
- ALOGI("%s: sBluetoothHfpInterface: %p", __FUNCTION__, sBluetoothHfpInterface);
- if (!sBluetoothHfpInterface) return JNI_FALSE;
- addr = env->GetByteArrayElements(address, NULL);
- if (!addr) {
- jniThrowIOException(env, EINVAL);
- return JNI_FALSE;
- }
- <span style="color:#ff0000;">if ((status = sBluetoothHfpInterface->connect((bt_bdaddr_t *)addr)) != BT_STATUS_SUCCESS) {</span>
- ALOGE("Failed HF connection, status: %d", status);
- }
- env->ReleaseByteArrayElements(address, addr, 0);
- return (status == BT_STATUS_SUCCESS) ? JNI_TRUE : JNI_FALSE;
关键函数是sBluetoothHfpInterface->connect((bt_bdaddr_t
*)addr), connect定义在 hardware/libhardware/include/hardware/bt_hf.h,
但是实现却在:external/bluetooth/bluedroid/btif/src/btif_hf.c 中实现
- #include <hardware/bt_hf.h>
- static bt_status_t connect( bt_bdaddr_t *bd_addr )
- {
- CHECK_BTHF_INIT();
- return btif_queue_connect(UUID_SERVCLASS_AG_HANDSFREE, bd_addr, connect_int);
- }
看定义,直接连接handsfree
#define UUID_SERVCLASS_AG_HANDSFREE 0X111F /* Handsfree profile */
btif_queue_connect的定义在下面文件中定义
external/bluetooth/bluedroid/btif/src/btif_profile_queue.c
进入bt_status_t btif_queue_connect看定义:
- bt_status_t btif_queue_connect(uint16_t uuid, const bt_bdaddr_t *bda,
- btif_connect_cb_t *connect_cb)
- {
- connect_node_t node;
- memset(&node, 0, sizeof(connect_node_t));
- memcpy(&(node.bda), bda, sizeof(bt_bdaddr_t));
- node.uuid = uuid;
- node.p_cb = connect_cb;
- return btif_transfer_context(queue_int_handle_evt, BTIF_QUEUE_CONNECT_EVT,
- (char*)&node, sizeof(connect_node_t), NULL);
- }
btif_transfer_context定义在如下文件中
external/bluetooth/bluedroid/btif/src/btif_core.c
btif_transfer_context内容就不粘贴了,里面发送消息,调用
external/bluetooth/bluedroid/gki/common/gki_buffer.c
- void GKI_send_msg (UINT8 task_id, UINT8 mbox, void *msg)
GKI_send_msg发送一条GKI信息到BTA,GKI_send_msg有三个参数,第一个参数是线程id,也作为task id, 通过bta_sys_init获得,第二个参数是mailbox id,第三个是上一步封装好的p_msg