BackupManager.java revision 3de55bcd34afd5871816526294f9514d1adf3fe5 
1/*
2 * Copyright (C) 2009 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 android.app.backup;
18
19import android.app.backup.RestoreSession;
20import android.app.backup.IBackupManager;
21import android.app.backup.IRestoreSession;
22import android.content.Context;
23import android.os.RemoteException;
24import android.os.ServiceManager;
25import android.util.Log;
26
27/**
28 * BackupManager is the interface to the system's backup service. Applications
29 * simply instantiate one, and then use that instance to communicate with the
30 * backup infrastructure.
31 * <p>
32 * When an application has made changes to data which should be backed up, a
33 * call to {@link #dataChanged()} will notify the backup service. The system
34 * will then schedule a backup operation to occur in the near future. Repeated
35 * calls to {@link #dataChanged()} have no further effect until the backup
36 * operation actually occurs.
37 * <p>
38 * The backup operation itself begins with the system launching the
39 * {@link android.app.backup.BackupAgent} subclass declared in your manifest. See the
40 * documentation for {@link android.app.backup.BackupAgent} for a detailed description
41 * of how the backup then proceeds.
42 * <p>
43 * A simple implementation of a BackupAgent useful for backing up Preferences
44 * and files is available by using {@link android.app.backup.BackupHelperAgent}.
45 * <p>
46 * STOPSHIP: more documentation!
47 * <p>
48 * <b>XML attributes</b>
49 * <p>
50 * See {@link android.R.styleable#AndroidManifestApplication
51 * AndroidManifest.xml's application attributes}
52 *
53 * @attr ref android.R.styleable#AndroidManifestApplication_allowBackup
54 * @attr ref android.R.styleable#AndroidManifestApplication_backupAgent
55 * @attr ref android.R.styleable#AndroidManifestApplication_killAfterRestore
56 */
57public class BackupManager {
58    private static final String TAG = "BackupManager";
59
60    private Context mContext;
61    private static IBackupManager sService;
62
63    private static void checkServiceBinder() {
64        if (sService == null) {
65            sService = IBackupManager.Stub.asInterface(
66                    ServiceManager.getService(Context.BACKUP_SERVICE));
67        }
68    }
69
70    /**
71     * Constructs a BackupManager object through which the application can
72     * communicate with the Android backup system.
73     *
74     * @param context The {@link android.content.Context} that was provided when
75     *                one of your application's {@link android.app.Activity Activities}
76     *                was created.
77     */
78    public BackupManager(Context context) {
79        mContext = context;
80    }
81
82    /**
83     * Notifies the Android backup system that your application wishes to back up
84     * new changes to its data.  A backup operation using your application's
85     * {@link android.app.backup.BackupAgent} subclass will be scheduled when you call this method.
86     */
87    public void dataChanged() {
88        checkServiceBinder();
89        if (sService != null) {
90            try {
91                sService.dataChanged(mContext.getPackageName());
92            } catch (RemoteException e) {
93                Log.d(TAG, "dataChanged() couldn't connect");
94            }
95        }
96    }
97
98    /**
99     * Convenience method for callers who need to indicate that some other package
100     * needs a backup pass.  This can be relevant in the case of groups of packages
101     * that share a uid, for example.
102     *
103     * This method requires that the application hold the "android.permission.BACKUP"
104     * permission if the package named in the argument is not the caller's own.
105     */
106    public static void dataChanged(String packageName) {
107        checkServiceBinder();
108        if (sService != null) {
109            try {
110                sService.dataChanged(packageName);
111            } catch (RemoteException e) {
112                Log.d(TAG, "dataChanged(pkg) couldn't connect");
113            }
114        }
115    }
116
117    /**
118     * Begin the process of restoring data from backup.  See the
119     * {@link android.app.backup.RestoreSession} class for documentation on that process.
120     */
121    public RestoreSession beginRestoreSession() {
122        RestoreSession session = null;
123        checkServiceBinder();
124        if (sService != null) {
125            try {
126                String transport = sService.getCurrentTransport();
127                IRestoreSession binder = sService.beginRestoreSession(transport);
128                session = new RestoreSession(mContext, binder);
129            } catch (RemoteException e) {
130                Log.w(TAG, "beginRestoreSession() couldn't connect");
131            }
132        }
133        return session;
134    }
135}
136