选择MTP,PTP,UMS的选项界面就定义在UsbSettings.java,选择其中一个选项时会执行以下代码。
packages/apps/Settings/src/com/android/settings/deviceinfo/UsbSettings.java
if (preference == mMtp) { mUsbManager.setCurrentFunction(UsbManager.USB_FUNCTION_MTP, true); updateToggles(UsbManager.USB_FUNCTION_MTP); } else if (preference == mPtp) { mUsbManager.setCurrentFunction(UsbManager.USB_FUNCTION_PTP, true); updateToggles(UsbManager.USB_FUNCTION_PTP); } else if(preference == mUms) { mUsbManager.setCurrentFunction(UsbManager.USB_FUNCTION_MASS_STORAGE, true); updateToggles(UsbManager.USB_FUNCTION_MASS_STORAGE); }
updateToggle就是去让执行某些选项的选中与取消工作。
其中最重要的是mUsbManager.setCurrentFunction(),mUsbManger是这样得到的:
@Override public void onCreate(Bundle icicle) { super.onCreate(icicle); mUsbManager = (UsbManager)getSystemService(Context.USB_SERVICE); }
它的接口实现在frameworks/base/core/java/android/hardware/usb/IUsbManager.aidl
frameworks/base/services/java/com/android/server/usb/UsbService.java
/** * UsbService manages all USB related state, including both host and device support. * Host related events and calls are delegated to UsbHostManager, and device related * support is delegated to UsbDeviceManager. */ public class UsbService extends IUsbManager.Stub { private final Context mContext; private UsbDeviceManager mDeviceManager; private UsbHostManager mHostManager; private final UsbSettingsManager mSettingsManager;
这个界面就是"com.android.settings.UsbSettings" Activity。在frameworks/base/services/java/com/android/server/usb/UsbDeviceManager.java中被调用。
如果你选择了USB调试功能,还会弹出"com.android.settings.DevelopmentSettings" Activity,也是在UsbDeviceManager.java中被调用。关于UsbDevcieManager,我们以后再细看。
如果你选择了UMS,还会弹出"com.android.systemui.usb.UsbStorageActivity" Activity,就是“打开USB存储设备”的界面。它就义在定义在:
frameworks/base/packages/SystemUI/src/com/android/systemui/usb/UsbStorageActivity.java。
这些界面只有在插入USB时才会有通知显示。在没有插USB的情况下,有些界面是没有入口的。我们就以UsbStorageActivity为例,介绍一下这些通知是怎么弹出来的。
frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBarPolicy.java
// storage mStorageManager = (StorageManager) context.getSystemService(Context.STORAGE_SERVICE); mStorageManager.registerListener( new com.android.systemui.usb.StorageNotification(context));这里注册了监听函数com.android.systemui.usb.StorageNotification,这个只是针对Phone,对于平板,有tablet/TabletStatusBarPolicy.java
我们来看一下注册的com.android.systemui.usb.StorageNotification
frameworks/base/packages/SystemUI/src/com/android/systemui/usb/StorageNotification.java
public class StorageNotification extends StorageEventListener { private static final String TAG = "StorageNotification"; public StorageNotification(Context context) { mContext = context; mStorageManager = (StorageManager) context.getSystemService(Context.STORAGE_SERVICE); final boolean connected = mStorageManager.isUsbMassStorageConnected(); Slog.d(TAG, String.format( "Startup with UMS connection %s (media state %s)", mUmsAvailable, Environment.getExternalStorageState())); HandlerThread thr = new HandlerThread("SystemUI StorageNotification"); thr.start(); mAsyncEventHandler = new Handler(thr.getLooper()); onUsbMassStorageConnectionChanged(connected); }
在构造函数里就调用了onUsbMassStorageConnectionChanged函数,它最终会调到updateUsbMassStorageNotification(),
/** * Update the state of the USB mass storage notification */ void updateUsbMassStorageNotification(boolean available) { if (available) { Intent intent = new Intent(); intent.setClass(mContext, com.android.systemui.usb.UsbStorageActivity.class); intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK); PendingIntent pi = PendingIntent.getActivity(mContext, 0, intent, 0); setUsbStorageNotification( com.android.internal.R.string.usb_storage_notification_title, com.android.internal.R.string.usb_storage_notification_message, com.android.internal.R.drawable.stat_sys_data_usb, false, true, pi); } else { setUsbStorageNotification(0, 0, 0, false, false, null); } }
也就是说UsbStorageActivity和StorageNotification绑定在了一起,什么时候弹出这个通知,就可以进入这个Activity了。
如果连接了USB,就会在通知栏里显示USB选项的通知。如果没有连接,就会把这个通知给取消掉。那我们看一下,这个通知是怎么弹出来的。
frameworks/base/core/java/android/os/storage/StorageManager.java
public void registerListener(StorageEventListener listener) { if (listener == null) { return; } synchronized (mListeners) { mListeners.add(new ListenerDelegate(listener)); } }mListeners会被私有成员MountServiceBinderListener用到,而MountServiceBinderListener又是继承自IMountServiceListener.Stub,在构造函数里被注册。
public StorageManager(Looper tgtLooper) throws RemoteException { mMountService = IMountService.Stub.asInterface(ServiceManager.getService("mount")); if (mMountService == null) { Log.e(TAG, "Unable to connect to mount service! - is it running yet?"); return; } mTgtLooper = tgtLooper; mBinderListener = new MountServiceBinderListener(); mMountService.registerListener(mBinderListener); }所以关键还是在mMountService。