蓝牙耳机Priority设置流程
当蓝牙耳机配对成功后，会发送一个BONDING_STATE_CHANGE的消息，在BondStateMachine状态机里会对这个消息进行处理，调用setProfilePriorty(dev)函数对当前的耳机进行优先级的设置，
把以前的设置优先级顺序Hid、A2DP、Headset改为Headset、A2DP、Hid，请看这个函数修改后的具体code：
private void setProfilePriorty(BluetoothDevice device){
HidService hidService = HidService.getHidService();
A2dpService a2dpService = A2dpService.getA2dpService();
HeadsetService headsetService = HeadsetService.getHeadsetService();
if ((headsetService != null) &&
(headsetService.getPriority(device)== BluetoothProfile.PRIORITY_UNDEFINED)){
headsetService.setPriority(device,BluetoothProfile.PRIORITY_ON);
}
if ((a2dpService != null) &&
(a2dpService.getPriority(device) ==BluetoothProfile.PRIORITY_UNDEFINED)){
a2dpService.setPriority(device,BluetoothProfile.PRIORITY_ON);
}
if((hidService != null) &&
(hidService.getPriority(device) ==BluetoothProfile.PRIORITY_UNDEFINED)){
hidService.setPriority(device,BluetoothProfile.PRIORITY_ON);
}
}
会把当前耳机的Headset Profile 和A2DP Profile的优先级设置为PRIORITY_ON。
当蓝牙耳机连接成功时，processProfileStateChanged函数会调用 setProfileAutoConnectionPriority(device,profileId)函数设置优先级，看修改后这个函数的具体code：
void setProfileAutoConnectionPriority(BluetoothDevice device, int profileId){
HeadsetService hsService = HeadsetService.getHeadsetService();
A2dpService a2dpService =A2dpService.getA2dpService();
if ((hsService != null) &&
(BluetoothProfile.PRIORITY_AUTO_CONNECT !=hsService.getPriority(device))){
adjustOtherHeadsetPriorities(hsService,device);
hsService.setPriority(device,BluetoothProfile.PRIORITY_AUTO_CONNECT);
}
if ((a2dpService != null)&&
(BluetoothProfile.PRIORITY_AUTO_CONNECT != a2dpService.getPriority(device))){
adjustOtherSinkPriorities(a2dpService, device);
a2dpService.setPriority(device,BluetoothProfile.PRIORITY_AUTO_CONNECT);
}
}
会把当前耳机的Headset和A2DP的Profile优先级都设置为PRIORITY_AUTO_CONNECT，同时会把其他的耳机设备的优先级设为PRIORITY_ON，保证耳机自动连接优先级的设备只有一个。
蓝牙耳机自动连接过程：
当蓝牙打开时，如果有配对的蓝牙耳机存在，就会根据它的优先级，判断是否进行自动连接。如果优先级为PRIORITY_AUTO_CONNECT，该耳机就会自动进行连接。