Android4.4 蓝牙源码部分分析

最近GOOGLE发布了Android4.4，看了一下源码；4.4的蓝牙打开流程这一部分还是有些变化的，从界面上看蓝牙开关就是设置settings里那个switch开关，widget开关当然也可以，起点不同后续的流程是一样的。先来看systemServer.java的代码，蓝牙服务开启的地方，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()是判断是否已打开蓝牙的，如果已打开，后续操作要执行开启蓝牙的动作

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，如下

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);
        }
    }

其中

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



获取到的值是在String文件中定义的，如：

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


表示如果开启飞行模式下，哪些服务将会被关闭。所以registerForAirplaneMode方法就是在如果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相应广播。

界面上开关就是BluetoothEnabler.java这个类了，而setBluetoothEnabled()则是具体开关动作。其中有开关的回调函数，代码如下：

    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);
    }

Android4.4 蓝牙源码部分分析,,5-wow.com