MtpDocumentsService.java revision a57d9ed09003acd8b2beb0494a2bd32f7030cc11 
1/*
2 * Copyright (C) 2015 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.mtp;
18
19import android.app.Notification;
20import android.app.Service;
21import android.app.NotificationManager;
22import android.content.Intent;
23import android.hardware.usb.UsbDevice;
24import android.os.IBinder;
25import android.util.Log;
26
27import com.android.internal.util.Preconditions;
28
29import java.io.IOException;
30
31/**
32 * Service to manage lifetime of DocumentsProvider's process.
33 * The service prevents the system from killing the process that holds USB connections. The service
34 * starts to run when the first MTP device is opened, and stops when the last MTP device is closed.
35 */
36public class MtpDocumentsService extends Service {
37    static final String ACTION_OPEN_DEVICE = "com.android.mtp.OPEN_DEVICE";
38    static final String ACTION_CLOSE_DEVICE = "com.android.mtp.CLOSE_DEVICE";
39    static final String EXTRA_DEVICE = "device";
40    private static final int FOREGROUND_NOTIFICATION_ID = 1;
41
42    NotificationManager mNotificationManager;
43
44    @Override
45    public IBinder onBind(Intent intent) {
46        // The service is used via intents.
47        return null;
48    }
49
50    @Override
51    public void onCreate() {
52        super.onCreate();
53        mNotificationManager = getSystemService(NotificationManager.class);
54    }
55
56    @Override
57    public int onStartCommand(Intent intent, int flags, int startId) {
58        // If intent is null, the service was restarted.
59        if (intent != null) {
60            final MtpDocumentsProvider provider = MtpDocumentsProvider.getInstance();
61            final UsbDevice device = intent.<UsbDevice>getParcelableExtra(EXTRA_DEVICE);
62            try {
63                Preconditions.checkNotNull(device);
64                switch (intent.getAction()) {
65                    case ACTION_OPEN_DEVICE:
66                        provider.openDevice(device.getDeviceId());
67                        break;
68
69                    case ACTION_CLOSE_DEVICE:
70                        provider.closeDevice(device.getDeviceId());
71                        break;
72
73                    default:
74                        throw new IllegalArgumentException("Received unknown intent action.");
75                }
76            } catch (IOException | InterruptedException | IllegalArgumentException error) {
77                logErrorMessage(error);
78            }
79        } else {
80            // TODO: Fetch devices again.
81        }
82
83        return updateForegroundState() ? START_STICKY : START_NOT_STICKY;
84    }
85
86    /**
87     * Updates the foreground state of the service.
88     * @return Whether the service is foreground or not.
89     */
90    private boolean updateForegroundState() {
91        final MtpDocumentsProvider provider = MtpDocumentsProvider.getInstance();
92        final int[] deviceIds = provider.getOpenedDeviceIds();
93        String message = null;
94        if (deviceIds.length != 0) {
95            // TODO: Localize the message.
96            // TODO: Add buttons "Open in Files" and "Open in Apps" if needed.
97            if (deviceIds.length > 1) {
98                message = deviceIds.length + " devices are being connected.";
99            } else {
100                try {
101                    message = provider.getDeviceName(deviceIds[0]) + " is being connected.";
102                } catch (IOException exp) {
103                    logErrorMessage(exp);
104                    // If we failed to obtain device name, it looks the device is unusable.
105                    // Because this is the last device we opened, we should hide the notification
106                    // for the case.
107                    try {
108                        provider.closeDevice(deviceIds[0]);
109                    } catch (IOException | InterruptedException closeError) {
110                        logErrorMessage(closeError);
111                    }
112                }
113            }
114        }
115        if (message != null) {
116            final Notification notification = new Notification.Builder(this)
117                    .setContentTitle(message)
118                    .setSmallIcon(android.R.drawable.ic_menu_camera)
119                    .setCategory(Notification.CATEGORY_SYSTEM)
120                    .setPriority(Notification.PRIORITY_LOW)
121                    .build();
122            startForeground(FOREGROUND_NOTIFICATION_ID, notification);
123            return true;
124        } else {
125            stopForeground(true /* removeNotification */);
126            stopSelf();
127            return false;
128        }
129    }
130
131    private static void logErrorMessage(Exception exp) {
132        if (exp.getMessage() != null) {
133            Log.e(MtpDocumentsProvider.TAG, exp.getMessage());
134        } else {
135            Log.e(MtpDocumentsProvider.TAG, exp.toString());
136        }
137    }
138}
139