I'm working on an Android app that uses a SQLite database for storing survey data.

Problem: For Android version 10 and above devices,I can't store a backup copy of an SQLite database in some folder that won't be deleted even if app is uninstalled

For devices before Android version 10 it works fine with code below:

 folder = Environment.getExternalStoragePublicDirectory("Db_Backup");// Folder Name

 if (!folder.exists())
    folder.mkdirs(); //Db_Backup folder gets created

For devices with Android version 11,it is not working

For android 10 and 11 devices, I have tried using code as below:

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
   Files[] files=getExternalFilesDirs(Environment.DIRECTORY_DOWNLOADS);
   folder=files[0]; 
   // OR
   folder = getFilesDir();

   if (!folder.exists())
      folder.mkdirs(); // Db_Backup folder is created in app directory 
   ......
}

Above code creates a backup copy to android/data/com.example.packagename/files/backup/{filename.db} this location only

Issue: when app is uninstalled or app data gets cleared the .db backup file also gets removed or cleared

exportDatabaseNew() function that I am using is as below:

    private void exportDatabaseNew(LinearLayout linearLayout) {

    FileOutputStream output = null;
    try {
        File dbFile = getDatabasePath(DatabaseHelper.DATABASE_NAME);
        FileInputStream fis = new FileInputStream(dbFile);
        File[] files;
        File folder = null;
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
            files=getExternalFilesDirs("Db_Backup");
            folder=files[0];
            Log.i("export", "exportDatabaseNew: "   folder.getAbsolutePath());
        } else {
            folder = Environment.getExternalStoragePublicDirectory("Db_Backup");//Folder Name
            Log.i("export", "exportDatabaseNew: "   folder.getAbsolutePath());
        }

        if (!folder.exists())
            folder.mkdirs();

        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd", Locale.US);
        String currentDate = df.format(new Date());
     
        String backupName = "Survey_"   currentDate   ".db";

        File myFile = new File(folder, backupName);// Filename

        output = new FileOutputStream(myFile);
        byte[] buffer = new byte[1024];
        int length;
        while ((length = fis.read(buffer)) > 0) {
            output.write(buffer, 0, length);
        }
        // Close the streams
        output.flush();
        output.close();
        fis.close();
      
        Snackbar.make(linearLayout, R.string.backup_complete, Snackbar.LENGTH_LONG)
                .show();
    } catch (Exception e) {
        e.printStackTrace();

    } finally {
        if (output != null) {
            try {
                output.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

CodePudding user response：

For Android 11, you have to either:

1. Save files in your application directory
2. Save files into public directories
3. If you really must, any other location that is NOT a different app directory, it requires the following permission:

< uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE" tools:ignore="ScopedStorage"/>

This permission only applies for android 11 and above. Do note that if you want your app to be published on Google Play Store you'll need to provide a good reason why you want this permission and you are not willing to simply store it as part of your app's files.

CodePudding user response：

Create your own folder in public Documents directory and write your file to that folder.