Android Data Backup
In this article, we will discuss the various aspects of Android data backup, including registration of an application with the Google backup service, backup agent, backup helpers, and code examples for both SharedPreferencesBackupHelper and FileBackupHelper.
As an Android developer, you may know that user data such as preferences, settings, and user-generated content are important for your application. To ensure that your users do not lose their data in case of device loss, accidental deletion, or application reinstallation, it is crucial to provide a backup and restore functionality for this data. Luckily, Android offers a built-in backup and restore framework that enables you to easily backup and restore application data to remote cloud storage.
Registering an App with Google Backup Service
If you want to add backup and restore functionality to your Android application, you will have to register your app with the Google backup service. This can be done by adding a meta-data tag to your application’s AndroidManifest.xml file.
<application android:allowBackup="true" android:backupAgent="MyBackupPlace"> <meta-data android:name="com.google.android.backup.api_key" android:value="AEdPqrEAAAAIErlxFByGgNz2ywBeQb6TsmLpp5Ksh1PW-ZSexg" /> </application>
When setting up backup and restore functionality for your Android app, you will need to include the android:allowBackup attribute in your application’s AndroidManifest.xml file to enable this feature.
Additionally, the android:backupAgent attribute should be included, specifying the name of the class that extends BackupAgentHelper. Lastly, the com.google.android.backup.api_key meta-data tag should be added, which requires an API key provided by the Google backup service to identify your application.
Creating a Backup Agent
To handle all data backup operations, you will need to use the BackupAgentHelper class provided by Android. You can create a backup agent by extending this class, allowing you to utilize its functionality. The syntax for creating a backup agent is as follows.
public class MyBackUpPlace extends BackupAgentHelper {
}Backup Helpers
If you are looking to backup persistent data in your Android application, it will typically be stored in either the form of SharedPreferences or File. To assist with backing up these two data types, Android provides two backup helper classes: SharedPreferencesBackupHelper and FileBackupHelper.
SharedPreferencesBackupHelper
SharedPreferencesBackupHelper is a backup helper class provided by Android for backing up SharedPreferences data. If you’re using SharedPreferencesBackupHelper in your Android application, you can take advantage of the following methods:
| Methods | Overview |
| constructor | To create a new instance of SharedPreferencesBackupHelper, you can use the constructor that takes two parameters – a Context object and an array of String values representing the names of the SharedPreferences groups that need to be backed up. |
| performBackup(ParcelFileDescriptor oldState, BackupDataOutput data, ParcelFileDescriptor newState) | This method is called during backup operations and takes three parameters. The first is the old state of the application, the second is a BackupDataOutput object used to write the backup data, and the third is the new state of the application after the backup. |
| restoreEntity(BackupDataInputStream data) | When your application is being restored, this method is called and takes a single parameter – a BackupDataInputStream object that contains the backed-up data. You can use this method to read the data and restore the SharedPreferences data to the device. |
| getFilesDir() | This method returns the directory where the SharedPreferences files are stored. |
| getSharedPreferences() | This method returns an instance of SharedPreferences that can be used to access the SharedPreferences data. |
When using SharedPreferencesBackupHelper, you will need to instantiate its object with the name of your SharedPreferences file, as shown below.
static final String FILE_NAME_OF_PREFERENCES = "myPreferences"; SharedPreferencesBackupHelper helper = new SharedPreferencesBackupHelper(this, FILE_NAME_OF_PREFERENCES);
To backup and restore all the groups of SharedPreferences that are specified in the SharedPreferencesBackupHelper object, you can use the SharedPreferencesBackupHelper class. To add a helper to a given data subset to the agent’s configuration, you can call the addHelper method, which is shown below.
addHelper(PREFS_BACKUP_KEY, helper);
Here, we use PREFS_BACKUP_KEY as a string to identify our backup data.
FileBackupHelper
FileBackupHelper is a backup helper class in Android that provides backup and restore functionality for application files.
If you’re working with the FileBackupHelper class in Android, you can use the following methods:
| Methods | Overview |
| Constructor | Create a new instance of the FileBackupHelper class with a specified context and file name. |
| performBackup() | Back up the specified files when called by the backup framework. It requires a backup data output stream as an argument. |
| restoreEntity() | Restore the specified files when called by the restore framework. It requires a backup data input stream and an entity header as arguments. |
| writeNewStateDescription() | Write a new state description for the specified files when called by the backup framework. It requires a backup data output stream as an argument. |
| getFile() | Get the File object for the specified file name. |
| onRestoreFinished() | Perform any cleanup or initialization tasks after all data has been restored. This method is called by the restore framework. |
| onRestoreFile() | Restore a single file when called by the restore framework. It requires a File object and a ParcelFileDescriptor as arguments. |
| onBackupFile() | Back up a single file when called by the backup framework. It requires a File object and a ParcelFileDescriptor as arguments. |
To use FileBackupHelper, you will need to create an object of this class by specifying the file name of the data that you want to backup, as shown below.
FileBackupHelper helper = new FileBackupHelper(this, FILE_NAME_OF_DATA);
To add a helper to a given data subset to your agent’s configuration, you can call the addHelper method, which is shown below.
addHelper(DATA_BACKUP_KEY, helper);
Here, DATA_BACKUP_KEY is a string that identifies our backup data.
Backup and Restore Methods
To backup and restore your application data using the Android Backup Service, you need to use the backup and restore methods. The BackupAgentHelper class provides a set of methods that you can use to perform these operations. Here are the main methods you need to know:
| Methods | Overview |
| onBackup() | This method is called when it’s time to backup your application data. You should override this method in your BackupAgentHelper subclass and implement your backup logic here. |
| onRestore() | This method is called when it’s time to restore your application data. You should override this method in your BackupAgentHelper subclass and implement your restore logic here. |
| getFilesDir() | This method returns the absolute path to the directory on the filesystem where files created with openFileOutput(String, int) are stored. |
| getDatabasePath(String) | This method returns the absolute path to the private database file that is associated with the specified database name. |
| getSharedPreferences(String, int) | This method returns an instance of the SharedPreferences that is associated with the specified name and mode. |
Advantages of Data Backup
Android data backup provides you with several advantages, such as:
| Advantages | Overview |
| Protection of data | Your user’s data is backed up to remote cloud storage, ensuring that it’s protected from loss in case of device loss, accidental deletion, or application reinstallation. |
| Improved user experience | Backup and restore functionality enables users to upgrade or switch devices without worrying about losing their data, thus providing a seamless experience. |
| Easy implementation | Android’s built-in backup and restore framework makes it simple for you to implement backup and restore functionality in your application. |
| Reduced development time | By using the built-in backup and restore framework, you can save time and effort in developing your own backup and restore solutions. |
| Increased user trust | Providing backup and restore functionality in your application can increase user trust and confidence, as users are more likely to trust applications that take steps to protect their data. |
You have learned about the various aspects of Android data backup in this article, including how to register your application with the Google backup service, create a backup agent, and use backup helpers such as SharedPreferencesBackupHelper and FileBackupHelper. By leveraging the built-in Android backup and restore framework, you can provide a safe and secure environment for your users’ data, even in situations like device loss, accidental deletion, or application reinstallation.
