BackupManager.java revision 4528186e0d65fc68ef0dd1941aa2ac8aefcd55a3 
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
56 *       android.R.styleable#AndroidManifestApplication_restoreNeedsApplication
57 * @attr ref android.R.styleable#AndroidManifestApplication_killAfterRestore
58 */
59public class BackupManager {
60    private static final String TAG = "BackupManager";
61
62    private Context mContext;
63    private static IBackupManager sService;
64
65    private static void checkServiceBinder() {
66        if (sService == null) {
67            sService = IBackupManager.Stub.asInterface(
68                    ServiceManager.getService(Context.BACKUP_SERVICE));
69        }
70    }
71
72    /**
73     * Constructs a BackupManager object through which the application can
74     * communicate with the Android backup system.
75     *
76     * @param context The {@link android.content.Context} that was provided when
77     *                one of your application's {@link android.app.Activity Activities}
78     *                was created.
79     */
80    public BackupManager(Context context) {
81        mContext = context;
82    }
83
84    /**
85     * Notifies the Android backup system that your application wishes to back up
86     * new changes to its data.  A backup operation using your application's
87     * {@link android.app.backup.BackupAgent} subclass will be scheduled when you call this method.
88     */
89    public void dataChanged() {
90        checkServiceBinder();
91        if (sService != null) {
92            try {
93                sService.dataChanged(mContext.getPackageName());
94            } catch (RemoteException e) {
95                Log.d(TAG, "dataChanged() couldn't connect");
96            }
97        }
98    }
99
100    /**
101     * Convenience method for callers who need to indicate that some other package
102     * needs a backup pass.  This can be relevant in the case of groups of packages
103     * that share a uid, for example.
104     *
105     * This method requires that the application hold the "android.permission.BACKUP"
106     * permission if the package named in the argument is not the caller's own.
107     */
108    public static void dataChanged(String packageName) {
109        checkServiceBinder();
110        if (sService != null) {
111            try {
112                sService.dataChanged(packageName);
113            } catch (RemoteException e) {
114                Log.d(TAG, "dataChanged(pkg) couldn't connect");
115            }
116        }
117    }
118
119    /**
120     * Begin the process of restoring data from backup.  See the
121     * {@link android.app.backup.RestoreSession} class for documentation on that process.
122     */
123    public RestoreSession beginRestoreSession() {
124        RestoreSession session = null;
125        checkServiceBinder();
126        if (sService != null) {
127            try {
128                String transport = sService.getCurrentTransport();
129                IRestoreSession binder = sService.beginRestoreSession(transport);
130                session = new RestoreSession(mContext, binder);
131            } catch (RemoteException e) {
132                Log.w(TAG, "beginRestoreSession() couldn't connect");
133            }
134        }
135        return session;
136    }
137}
138