Cloud Sync

                                                       - Rahul Singh

INTRO

When you purchase a new device, we hate to lose the High scores of our favorite games on the old device.

Guess what!! Google Backup API is there to help!!

Syncing to the cloud

• By providing powerful APIs for internet connectivity, the Android framework helps you build rich cloud-enabled apps that sync their data to a remote web service, making sure all your devices always stay in sync, and your valuable data is always backed up to the cloud.
  
• All you need to do is integrate the Backup API into your Android Application, so that user data such as preferences, notes, and high scores update seamlessly across all of a user's devices

HOW

Register for the Android Backup Service

• Declare the name of the class that acts as your backup agent.

• Add the snippet below as a child element of the Application tag.

Assuming your backup agent is going to be called TheBackupAgent, here's an example of  what the manifest looks like with this tag included:

<application android:label="MyApp"
             android:backupAgent="TheBackupAgent">
    ...
    <meta-data android:name="com.google.android.backup.api_key"
    android:value="ABcDe1FGHij2KlmN3oPQRs4TUvW5xYZ" />
    ...
</application>

THe BAckup Agent

import android.app.backup.BackupAgentHelper;
import android.app.backup.FileBackupHelper;


 public class TheBackupAgent extends BackupAgentHelper {

 
    static final String HIGH_SCORES_FILENAME = "scores";

    
    static final String FILES_BACKUP_KEY = "myfiles";

    
    @Override
    void onCreate() {
        FileBackupHelper helper = new FileBackupHelper(this, HIGH_SCORES_FILENAME);
        addHelper(FILES_BACKUP_KEY, helper);
    }
} 

 FileBackupHelper's constructor can take a variable number of filenames.  You could just as easily have backed up both a high scores file and a game progress file just by adding an extra parameter, like this :

@Override
    void onCreate() {
        FileBackupHelper helper = new FileBackupHelper(this, HIGH_SCORES_FILENAME, PROGRESS_FILENAME);
        addHelper(FILES_BACKUP_KEY, helper);
    } 

  So, that was about backing up files. Lets backup the SharedPreferences.

import android.app.backup.BackupAgentHelper;
 import android.app.backup.SharedPreferencesBackupHelper;

 public class TheBackupAgent extends BackupAgentHelper {

 
     static final String PREFS_DISPLAY = "displayprefs";
     static final String PREFS_SCORES = "highscores";

     
     static final String MY_PREFS_BACKUP_KEY = "myprefs";

     void onCreate() {
         SharedPreferencesBackupHelper helper =
                 new SharedPreferencesBackupHelper(this, PREFS_DISPLAY, PREFS_SCORES);
         addHelper(MY_PREFS_BACKUP_KEY, helper);
     }
 } 

Restore

 We are done with the backup, lets restore the data.

 In order to request a backup, just create an instance of the BackupManager, and call it's  dataChanged() method.

import android.app.backup.BackupManager;
 ...

 public void requestBackup() {
   BackupManager bm = new BackupManager(this);
   bm.dataChanged();
 }