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/*
* 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;
import android.app.IBackupAgent;
import android.backup.BackupDataInput;
import android.backup.BackupDataOutput;
import android.content.Context;
import android.content.ContextWrapper;
import android.os.IBinder;
import android.os.ParcelFileDescriptor;
import android.os.RemoteException;
import android.util.Log;
import java.io.IOException;
/**
* This is the central interface between an application and Android's
* settings backup mechanism.
*
* @hide pending API solidification
*/
public abstract class BackupAgent extends ContextWrapper {
private static final String TAG = "BackupAgent";
public BackupAgent() {
super(null);
}
public void onCreate() {
}
public void onDestroy() {
}
/**
* The application is being asked to write any data changed since the
* last time it performed a backup operation. The state data recorded
* during the last backup pass is provided in the oldState file descriptor.
* If oldState is null, no old state is available and the application should perform
* a full backup. In both cases, a representation of the final backup state after
* this pass should be written to the file pointed to by the newStateFd file descriptor.
*
* @param oldState An open, read-only ParcelFileDescriptor pointing to the last backup
* state provided by the application. May be null, in which
* case no prior state is being provided and the application should
* perform a full backup.
* @param data An open, read/write ParcelFileDescriptor 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 ParcelFileDescriptor pointing to an empty
* file. The application should record the final backup state
* here after writing the requested data to dataFd.
*/
public abstract void onBackup(ParcelFileDescriptor oldState, BackupDataOutput data,
ParcelFileDescriptor newState);
/**
* The application is being restored from backup, and should replace any
* existing data with the contents of the backup. The backup data is
* provided in the file pointed to by the dataFd file descriptor. Once
* the restore is finished, the application should write a representation
* of the final state to the newStateFd file descriptor,
*
* @param data An open, read-only ParcelFileDescriptor pointing to a full snapshot
* of the application's data.
* @param newState An open, read/write ParcelFileDescriptor pointing to an empty
* file. The application should record the final backup state
* here after restoring its data from dataFd.
*/
public abstract void onRestore(BackupDataInput data, ParcelFileDescriptor newState)
throws IOException;
// ----- Core implementation -----
/**
* Returns the private interface called by the backup system. Applications will
* not typically override this.
*/
public IBinder onBind() {
return mBinder;
}
private final IBinder mBinder = new BackupServiceBinder().asBinder();
/** @hide */
public void attach(Context context) {
attachBaseContext(context);
}
// ----- IBackupService binder interface -----
private class BackupServiceBinder extends IBackupAgent.Stub {
private static final String TAG = "BackupServiceBinder";
public void doBackup(ParcelFileDescriptor oldState,
ParcelFileDescriptor data,
ParcelFileDescriptor newState) throws RemoteException {
// !!! TODO - real implementation; for now just invoke the callbacks directly
Log.v(TAG, "doBackup() invoked");
BackupDataOutput output = new BackupDataOutput(data.getFileDescriptor());
try {
BackupAgent.this.onBackup(oldState, output, newState);
} catch (RuntimeException ex) {
Log.d(TAG, "onBackup (" + BackupAgent.this.getClass().getName() + ") threw", ex);
throw ex;
}
}
public void doRestore(ParcelFileDescriptor data,
ParcelFileDescriptor newState) throws RemoteException {
// !!! TODO - real implementation; for now just invoke the callbacks directly
Log.v(TAG, "doRestore() invoked");
BackupDataInput input = new BackupDataInput(data.getFileDescriptor());
try {
BackupAgent.this.onRestore(input, newState);
} catch (IOException ex) {
Log.d(TAG, "onRestore (" + BackupAgent.this.getClass().getName() + ") threw", ex);
throw new RuntimeException(ex);
} catch (RuntimeException ex) {
Log.d(TAG, "onRestore (" + BackupAgent.this.getClass().getName() + ") threw", ex);
throw ex;
}
}
}
}
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