Android example source code file (SystemBackupAgent.java)

This example Android source code file (SystemBackupAgent.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, backupagenthelper, backupdataoutput, content, io, ioexception, os, override, parcelfiledescriptor, string, systembackupagent, tag, wallpaper_image, wallpaper_info, wallpapermanagerservice

The SystemBackupAgent.java Android example source code

/*
 * 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 com.android.server;

import android.app.backup.AbsoluteFileBackupHelper;
import android.app.backup.BackupDataInput;
import android.app.backup.BackupDataInputStream;
import android.app.backup.BackupDataOutput;
import android.app.backup.BackupHelper;
import android.app.backup.BackupAgentHelper;
import android.content.Context;
import android.os.ParcelFileDescriptor;
import android.os.ServiceManager;
import android.os.SystemService;
import android.util.Slog;

import java.io.File;
import java.io.IOException;

/**
 * Backup agent for various system-managed data, currently just the system wallpaper
 */
public class SystemBackupAgent extends BackupAgentHelper {
    private static final String TAG = "SystemBackupAgent";

    // These paths must match what the WallpaperManagerService uses
    private static final String WALLPAPER_IMAGE = "/data/data/com.android.settings/files/wallpaper";
    private static final String WALLPAPER_INFO = "/data/system/wallpaper_info.xml";

    @Override
    public void onBackup(ParcelFileDescriptor oldState, BackupDataOutput data,
            ParcelFileDescriptor newState) throws IOException {
        // We only back up the data under the current "wallpaper" schema with metadata
        WallpaperManagerService wallpaper = (WallpaperManagerService)ServiceManager.getService(
                Context.WALLPAPER_SERVICE);
        String[] files = new String[] { WALLPAPER_IMAGE, WALLPAPER_INFO };
        if (wallpaper != null && wallpaper.mName != null && wallpaper.mName.length() > 0) {
            // When the wallpaper has a name, back up the info by itself.
            // TODO: Don't rely on the innards of the service object like this!
            // TODO: Send a delete for any stored wallpaper image in this case?
            files = new String[] { WALLPAPER_INFO };
        }
        addHelper("wallpaper", new AbsoluteFileBackupHelper(SystemBackupAgent.this, files));
        super.onBackup(oldState, data, newState);
    }

    @Override
    public void onRestore(BackupDataInput data, int appVersionCode, ParcelFileDescriptor newState)
            throws IOException {
        // On restore, we also support a previous data schema "system_files"
        addHelper("wallpaper", new AbsoluteFileBackupHelper(SystemBackupAgent.this,
                new String[] { WALLPAPER_IMAGE, WALLPAPER_INFO }));
        addHelper("system_files", new AbsoluteFileBackupHelper(SystemBackupAgent.this,
                new String[] { WALLPAPER_IMAGE }));

        boolean success = false;
        try {
            super.onRestore(data, appVersionCode, newState);

            WallpaperManagerService wallpaper = (WallpaperManagerService)ServiceManager.getService(
                    Context.WALLPAPER_SERVICE);
            wallpaper.settingsRestored();
        } catch (IOException ex) {
            // If there was a failure, delete everything for the wallpaper, this is too aggresive,
            // but this is hopefully a rare failure.
            Slog.d(TAG, "restore failed", ex);
            (new File(WALLPAPER_IMAGE)).delete();
            (new File(WALLPAPER_INFO)).delete();
        }
    }
}