Android4.4 蓝牙源代码段分析

大家好，又见面了，我是全栈君。

最近GOOGLE发布时间Android4.4，我看了看源代码。4.4蓝牙打开过程或这部分的一些变化，判断蓝牙开关是从接口设置settings在里面switch开关，widget当然，它可以切换，也许启动不同的过程是相同的。第一眼systemServer.java该代码。。真机情况下我们关心的是最后一个else分支。

if (SystemProperties.get(“ro.kernel.qemu”).equals(“1”)) { Slog.i(TAG, “No Bluetooh Service (emulator)”); } else if (factoryTest == SystemServer.FACTORY_TEST_LOW_LEVEL) { Slog.i(TAG, “No Bluetooth Service (factory test)”); } else if (!context.getPackageManager().hasSystemFeature (PackageManager.FEATURE_BLUETOOTH)) { Slog.i(TAG, “No Bluetooth Service (Bluetooth Hardware Not Present)”); } else if (disableBluetooth) { Slog.i(TAG, “Bluetooth Service disabled by config”); } else { Slog.i(TAG, “Bluetooth Manager Service”); bluetooth = new BluetoothManagerService(context); ServiceManager.addService(BluetoothAdapter.BLUETOOTH_MANAGER_SERVICE, bluetooth); }

看下bluetoothManagerService的构造方法，我们看三个地方。 loadStoredNameAndAddress()是读取蓝牙打开默认名称的地方。isBluetoothPersistedStateOn()是推断是否已打开蓝牙的，假设已打开。兴许操作要运行开启蓝牙的动作

BluetoothManagerService(Context context) { mHandler = new BluetoothHandler(IoThread.get().getLooper());

mContext = context; mBluetooth = null; mQBluetooth = null; mBinding = false; mUnbinding = false; mEnable = false; mState = BluetoothAdapter.STATE_OFF; mQuietEnableExternal = false; mEnableExternal = false; mAddress = null; mName = null; mErrorRecoveryRetryCounter = 0; mContentResolver = context.getContentResolver(); mCallbacks = new RemoteCallbackList<IBluetoothManagerCallback>(); mQCallbacks = new RemoteCallbackList<IQBluetoothManagerCallback>(); mStateChangeCallbacks = new RemoteCallbackList<IBluetoothStateChangeCallback>(); IntentFilter filter = new IntentFilter(Intent.ACTION_BOOT_COMPLETED); filter.addAction(BluetoothAdapter.ACTION_LOCAL_NAME_CHANGED); filter.addAction(Intent.ACTION_USER_SWITCHED); registerForAirplaneMode(filter); mContext.registerReceiver(mReceiver, filter); loadStoredNameAndAddress(); if (isBluetoothPersistedStateOn()) { mEnableExternal = true; } }

另外的registerForAirplaneMode方法，例如以下

private void registerForAirplaneMode(IntentFilter filter) { final ContentResolver resolver = mContext.getContentResolver(); final String airplaneModeRadios = Settings.Global.getString(resolver, Settings.Global.AIRPLANE_MODE_RADIOS); final String toggleableRadios = Settings.Global.getString(resolver, Settings.Global.AIRPLANE_MODE_TOGGLEABLE_RADIOS); boolean mIsAirplaneSensitive = airplaneModeRadios == null ? true : airplaneModeRadios.contains(Settings.Global.RADIO_BLUETOOTH); if (mIsAirplaneSensitive) { filter.addAction(Intent.ACTION_AIRPLANE_MODE_CHANGED); } }

当中

Settings.Global.getString(resolver, Settings.Global.AIRPLANE_MODE_TOGGLEABLE_RADIOS)

获取到的值是在String文件里定义的，如：

<!– Comma-separated list of bluetooth, wifi, and cell. –> <string name=”def_airplane_mode_radios” translatable=”false”>cell,bluetooth,wifi,nfc,wimax</string>

表示假设开启飞行模式下，哪些服务将会被关闭。所以registerForAirplaneMode方法就是在假设蓝牙也受飞行模式影响。那么飞行模式的变化也将使蓝牙服务收到对应广播。

界面上开关就是BluetoothEnabler.java这个类了，而setBluetoothEnabled()则是详细开关动作。当中有开关的回调函数，代码例如以下：

public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) { // Show toast message if Bluetooth is not allowed in airplane mode if (isChecked && (WifiSettings.needPrompt(mContext) || !WirelessSettings.isRadioAllowed( mContext, Settings.Global.RADIO_BLUETOOTH))) { Toast.makeText(mContext, R.string.wifi_in_airplane_mode, Toast.LENGTH_SHORT).show(); // Reset switch to off buttonView.setChecked(false); }

// shouldn’t setBluetoothEnabled(true) in airplane mode. if (mLocalAdapter != null) { if (isChecked && WifiSettings.needPrompt(mContext)) { return; } mLocalAdapter.setBluetoothEnabled(isChecked); } mSwitch.setEnabled(false); }

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