Android example source code file (RestoreSession.java)

This example Android source code file (RestoreSession.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

android, app, application, can't, content, context, irestoresession, msg_restore_finished, msg_restore_sets_available, msg_restore_starting, msg_update, os, override, remoteexception, restoreobserver, restoreobserverwrapper, restoresession, string, tag, utilities

The RestoreSession.java Android example source code

/*
 * Copyright (C) 2010 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.app.backup.RestoreObserver;
import android.app.backup.RestoreSet;
import android.app.backup.IRestoreObserver;
import android.app.backup.IRestoreSession;
import android.content.Context;
import android.os.Handler;
import android.os.Message;
import android.os.RemoteException;
import android.util.Log;

/**
 * Interface for managing a restore session.
 * @hide
 */
public class RestoreSession {
    static final String TAG = "RestoreSession";

    final Context mContext;
    IRestoreSession mBinder;
    RestoreObserverWrapper mObserver = null;

    /**
     * Ask the current transport what the available restore sets are.
     *
     * @param observer a RestoreObserver object whose restoreSetsAvailable() method will
     *   be called on the application's main thread in order to supply the results of
     *   the restore set lookup by the backup transport.  This parameter must not be
     *   null.
     * @return Zero on success, nonzero on error.  The observer's restoreSetsAvailable()
     *   method will only be called if this method returned zero.
     */
    public int getAvailableRestoreSets(RestoreObserver observer) {
        int err = -1;
        RestoreObserverWrapper obsWrapper = new RestoreObserverWrapper(mContext, observer);
        try {
            err = mBinder.getAvailableRestoreSets(obsWrapper);
        } catch (RemoteException e) {
            Log.d(TAG, "Can't contact server to get available sets");
        }
        return err;
    }

    /**
     * Restore the given set onto the device, replacing the current data of any app
     * contained in the restore set with the data previously backed up.
     *
     * <p>Callers must hold the android.permission.BACKUP permission to use this method.
     *
     * @return Zero on success; nonzero on error.  The observer will only receive
     *   progress callbacks if this method returned zero.
     * @param token The token from {@link #getAvailableRestoreSets()} corresponding to
     *   the restore set that should be used.
     * @param observer If non-null, this binder points to an object that will receive
     *   progress callbacks during the restore operation.
     */
    public int restoreAll(long token, RestoreObserver observer) {
        int err = -1;
        if (mObserver != null) {
            Log.d(TAG, "restoreAll() called during active restore");
            return -1;
        }
        mObserver = new RestoreObserverWrapper(mContext, observer);
        try {
            err = mBinder.restoreAll(token, mObserver);
        } catch (RemoteException e) {
            Log.d(TAG, "Can't contact server to restore");
        }
        return err;
    }

    /**
     * Restore a single application from backup.  The data will be restored from the
     * current backup dataset if the given package has stored data there, or from
     * the dataset used during the last full device setup operation if the current
     * backup dataset has no matching data.  If no backup data exists for this package
     * in either source, a nonzero value will be returned.
     *
     * @return Zero on success; nonzero on error.  The observer will only receive
     *   progress callbacks if this method returned zero.
     * @param packageName The name of the package whose data to restore.  If this is
     *   not the name of the caller's own package, then the android.permission.BACKUP
     *   permission must be held.
     * @param observer If non-null, this binder points to an object that will receive
     *   progress callbacks during the restore operation.
     */
    public int restorePackage(String packageName, RestoreObserver observer) {
        int err = -1;
        if (mObserver != null) {
            Log.d(TAG, "restorePackage() called during active restore");
            return -1;
        }
        mObserver = new RestoreObserverWrapper(mContext, observer);
        try {
            err = mBinder.restorePackage(packageName, mObserver);
        } catch (RemoteException e) {
            Log.d(TAG, "Can't contact server to restore package");
        }
        return err;
    }

    /**
     * End this restore session.  After this method is called, the RestoreSession
     * object is no longer valid.
     *
     * <p>Note: The caller must invoke this method to end the restore session,
     *   even if {@link #restorePackage(String, RestoreObserver)} failed.
     */
    public void endRestoreSession() {
        try {
            mBinder.endRestoreSession();
        } catch (RemoteException e) {
            Log.d(TAG, "Can't contact server to get available sets");
        } finally {
            mBinder = null;
        }
    }

    /*
     * Nonpublic implementation here
     */

    RestoreSession(Context context, IRestoreSession binder) {
        mContext = context;
        mBinder = binder;
    }

    /*
     * We wrap incoming binder calls with a private class implementation that
     * redirects them into main-thread actions.  This serializes the restore
     * progress callbacks nicely within the usual main-thread lifecycle pattern.
     */
    private class RestoreObserverWrapper extends IRestoreObserver.Stub {
        final Handler mHandler;
        final RestoreObserver mAppObserver;

        static final int MSG_RESTORE_STARTING = 1;
        static final int MSG_UPDATE = 2;
        static final int MSG_RESTORE_FINISHED = 3;
        static final int MSG_RESTORE_SETS_AVAILABLE = 4;

        RestoreObserverWrapper(Context context, RestoreObserver appObserver) {
            mHandler = new Handler(context.getMainLooper()) {
                @Override
                public void handleMessage(Message msg) {
                    switch (msg.what) {
                    case MSG_RESTORE_STARTING:
                        mAppObserver.restoreStarting(msg.arg1);
                        break;
                    case MSG_UPDATE:
                        mAppObserver.onUpdate(msg.arg1, (String)msg.obj);
                        break;
                    case MSG_RESTORE_FINISHED:
                        mAppObserver.restoreFinished(msg.arg1);
                        break;
                    case MSG_RESTORE_SETS_AVAILABLE:
                        mAppObserver.restoreSetsAvailable((RestoreSet[])msg.obj);
                        break;
                    }
                }
            };
            mAppObserver = appObserver;
        }

        // Binder calls into this object just enqueue on the main-thread handler
        public void restoreSetsAvailable(RestoreSet[] result) {
            mHandler.sendMessage(
                    mHandler.obtainMessage(MSG_RESTORE_SETS_AVAILABLE, result));
        }

        public void restoreStarting(int numPackages) {
            mHandler.sendMessage(
                    mHandler.obtainMessage(MSG_RESTORE_STARTING, numPackages, 0));
        }

        public void onUpdate(int nowBeingRestored, String currentPackage) {
            mHandler.sendMessage(
                    mHandler.obtainMessage(MSG_UPDATE, nowBeingRestored, 0, currentPackage));
        }

        public void restoreFinished(int error) {
            mHandler.sendMessage(
                    mHandler.obtainMessage(MSG_RESTORE_FINISHED, error, 0));
        }
    }
}