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 17 package android.app.backup; 18 19 import android.os.ParcelFileDescriptor; 20 21 import java.io.IOException; 22 23 /** 24 * A convenient {@link BackupAgent} wrapper class that automatically manages 25 * heterogeneous data sets within the backup data, each identified by a unique 26 * key prefix. When processing a backup or restore operation, the BackupAgentHelper 27 * dispatches to one or more installed {@link BackupHelper} objects, each 28 * of which is responsible for a defined subset of the data being processed. 29 * <p> 30 * An application will typically extend this class in its own 31 * backup agent. Then, within the agent's {@link BackupAgent#onCreate() onCreate()} 32 * method, it will call {@link #addHelper(String, BackupHelper) addHelper()} one or more times to 33 * install the handlers for each kind of data it wishes to manage within its backups. 34 * <p> 35 * The Android framework currently provides two predefined {@link BackupHelper} classes:</p> 36 * <ul><li>{@link FileBackupHelper} - Manages the backup and restore of entire files 37 * within an application's data directory hierarchy.</li> 38 * <li>{@link SharedPreferencesBackupHelper} - Manages the backup and restore of an 39 * application's {@link android.content.SharedPreferences} data.</li></ul> 40 * <p> 41 * An application can also implement its own helper classes to work within the 42 * {@link BackupAgentHelper} framework. See the {@link BackupHelper} interface 43 * documentation for details. 44 * 45 * <div class="special reference"> 46 * <h3>Developer Guides</h3> 47 * <p>For more information about using BackupAgentHelper, read the 48 * <a href="{@docRoot}guide/topics/data/backup.html">Data Backup</a> developer guide.</p> 49 * </div> 50 * 51 * @see BackupHelper 52 * @see FileBackupHelper 53 * @see SharedPreferencesBackupHelper 54 */ 55 public class BackupAgentHelper extends BackupAgent { 56 static final String TAG = "BackupAgentHelper"; 57 58 BackupHelperDispatcher mDispatcher = new BackupHelperDispatcher(); 59 60 /** 61 * Run the backup process on each of the configured handlers. 62 */ 63 @Override 64 public void onBackup(ParcelFileDescriptor oldState, BackupDataOutput data, 65 ParcelFileDescriptor newState) throws IOException { 66 mDispatcher.performBackup(oldState, data, newState); 67 } 68 69 /** 70 * Run the restore process on each of the configured handlers. 71 */ 72 @Override 73 public void onRestore(BackupDataInput data, int appVersionCode, ParcelFileDescriptor newState) 74 throws IOException { 75 mDispatcher.performRestore(data, appVersionCode, newState); 76 } 77 78 /** @hide */ 79 public BackupHelperDispatcher getDispatcher() { 80 return mDispatcher; 81 } 82 83 /** 84 * Add a helper for a given data subset to the agent's configuration. Each helper 85 * must have a prefix string that is unique within this backup agent's set of 86 * helpers. 87 * 88 * @param keyPrefix A string used to disambiguate the various helpers within this agent 89 * @param helper A backup/restore helper object to be invoked during backup and restore 90 * operations. 91 */ 92 public void addHelper(String keyPrefix, BackupHelper helper) { 93 mDispatcher.addHelper(keyPrefix, helper); 94 } 95 } 96 97 98
