Android4.4 蓝牙源代码段分析

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);
    }