| /* |
| * Copyright (C) 2009 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package android.app.backup; |
| |
| import android.os.ParcelFileDescriptor; |
| |
| /** |
| * Defines the calling interface that {@link BackupAgentHelper} uses |
| * when dispatching backup and restore operations to the installed helpers. |
| * Applications can define and install their own helpers as well as using those |
| * provided as part of the Android framework. |
| * <p> |
| * Although multiple helper objects may be installed simultaneously, each helper |
| * is responsible only for handling its own data, and will not see entities |
| * created by other components within the backup system. Invocations of multiple |
| * helpers are performed sequentially by the {@link BackupAgentHelper}, with each |
| * helper given a chance to access its own saved state from within the state record |
| * produced during the previous backup operation. |
| * |
| * @see BackupAgentHelper |
| * @see FileBackupHelper |
| * @see SharedPreferencesBackupHelper |
| */ |
| public interface BackupHelper { |
| /** |
| * Based on <code>oldState</code>, determine which of the files from the |
| * application's data directory need to be backed up, write them to |
| * <code>data</code>, and fill in <code>newState</code> with the state as it |
| * exists now. |
| * <p> |
| * Implementing this method is much like implementing |
| * {@link BackupAgent#onBackup(ParcelFileDescriptor, BackupDataOutput, ParcelFileDescriptor) |
| * onBackup()} — the method parameters are the same. When this method is invoked the |
| * {@code oldState} descriptor points to the beginning of the state data |
| * written during this helper's previous backup operation, and the {@code newState} |
| * descriptor points to the file location at which the helper should write its |
| * new state after performing the backup operation. |
| * <p class="note"> |
| * <strong>Note:</strong> The helper should not close or seek either the {@code oldState} or |
| * the {@code newState} file descriptors.</p> |
| * |
| * @param oldState An open, read-only {@link android.os.ParcelFileDescriptor} pointing to the |
| * last backup state provided by the application. May be |
| * <code>null</code>, in which case no prior state is being |
| * provided and the application should perform a full backup. |
| * @param data An open, read/write {@link BackupDataOutput} |
| * pointing to the backup data destination. |
| * Typically the application will use backup helper classes to |
| * write to this file. |
| * @param newState An open, read/write {@link android.os.ParcelFileDescriptor} pointing to an |
| * empty file. The application should record the final backup |
| * state here after writing the requested data to the <code>data</code> |
| * output stream. |
| */ |
| public void performBackup(ParcelFileDescriptor oldState, BackupDataOutput data, |
| ParcelFileDescriptor newState); |
| |
| /** |
| * Called by {@link android.app.backup.BackupAgentHelper BackupAgentHelper} |
| * to restore a single entity from the restore data set. This method will be |
| * called for each entity in the data set that belongs to this handler. |
| * <p class="note"> |
| * <strong>Note:</strong> Do not close the <code>data</code> stream. Do not read more than |
| * {@link android.app.backup.BackupDataInputStream#size() size()} bytes from |
| * <code>data</code>.</p> |
| * |
| * @param data An open {@link BackupDataInputStream} from which the backup data can be read. |
| */ |
| public void restoreEntity(BackupDataInputStream data); |
| |
| /** |
| * Called by {@link android.app.backup.BackupAgentHelper BackupAgentHelper} |
| * after a restore operation to write the backup state file corresponding to |
| * the data as processed by the helper. The data written here will be |
| * available to the helper during the next call to its |
| * {@link #performBackup(ParcelFileDescriptor, BackupDataOutput, ParcelFileDescriptor) |
| * performBackup()} method. |
| * <p> |
| * This method will be called even if the handler's |
| * {@link #restoreEntity(BackupDataInputStream) restoreEntity()} method was never invoked during |
| * the restore operation. |
| * <p class="note"> |
| * <strong>Note:</strong> The helper should not close or seek the {@code newState} |
| * file descriptor.</p> |
| * |
| * @param newState A {@link android.os.ParcelFileDescriptor} to which the new state will be |
| * written. |
| */ |
| public void writeNewStateDescription(ParcelFileDescriptor newState); |
| } |
| |