Export and import SQLite database

Gabriel Delfino :

Good evening, I'm developing an android app, it has SQLite database, I need a way to copy the database to the external storage of the device, where I can copy to another device and so I can import the database into the another device.

For example:

Suppose the application calls "example", the database is in the "/data/data/com.gnd.example/databases" folder and it is called data.db, need to copy it to the "example / backup" folder ", for example" / storage / emulated / 0 / Example / Backup ". This is the first part.

The second part is the import, where the application should copy the file from the "example / import" folder to the folder "/data/data/com.gnd.example/databases"

For this I have a two button activity, btn_export and btn_import.

I have already relied on the following solutions:

import / export to android sqlite database Simple export and import of SQLite database on Android

I already inserted it in AndroidManifest

How do I ask the user for permission?

I tried copying using this code that I took in one of the examples

private void backupDatabase () throws IOException {
   String inFileName = "/data/data/com.gnd.example/databases/dados.db";
   File dbFile = new File (inFileName);
   FileInputStream fis = new FileInputStream (dbFile);

   String outFileName = Environment.getExternalStorageDirectory () + "/ example / backup / data.db";
   OutputStream output = new FileOutputStream (outFileName);
   byte [] buffer = new byte [1024];
   int length;
   while ((length = fis.read (buffer))> 0) {
       output.write (buffer, 0, length);
   }
   output.flush ();
   output.close ();
   fis.close ();

}

The button looks like this:

   @Override
   public void onClick (View view) {
       try {
           backupDatabase ();
       } catch (IOException e1) {
           e1.printStackTrace ();
       }
   
});

Log when I press the button:

07/01 19:35:39: Launching app
$ adb shell am start -n "com.gnd.keepkey / com.gnd.keepkey.Telephone" -a android.intent.action.MAIN -c android.intent.category.LAUNCHER
Client not ready yet..Waiting for process to come online
Waiting for process to come online
Connected to process 27724 on device motorola-moto_z2_play-0039635857
Capturing and displaying logcat messages from application. This behavior can be disabled in the "Logcat output" section of the "Debugger" settings page.
I / zygote: Do partial code cache collection, code = 20KB, data = 29KB
I / zygote: After code cache collection, code = 20KB, data = 29KB
    Increasing code cache capacity to 128KB
I / zygote: Do partial code cache collection, code = 20KB, data = 47KB
I / zygote: After code cache collection, code = 20KB, data = 47KB
    Increasing code cache capacity to 256KB
I / zygote: Compiler allocated 4MB to compile void android.widget.TextView. <Init> (android.content.Context, android.util.AttributeSet, int, int)
I / zygote: Full code cache collection, code = 120KB, data = 82KB
I / zygote: After code cache collection, code = 117KB, data = 62KB
I / zygote: Do partial code cache collection, code = 125KB, date = 79KB
I / zygote: After code cache collection, code = 125KB, data = 79KB
    Increasing code cache capacity to 512KB
W / System.err: java.io.FileNotFoundException: /storage/emulated/0/teste/dados.db (No such file or directory)
        at java.io.FileOutputStream.open0 (Native Method)
W / System.err: at java.io.FileOutputStream.open (FileOutputStream.java:287)
        at java.io.FileOutputStream. <init> (FileOutputStream.java:223)
        at java.io.FileOutputStream. <init> (FileOutputStream.java:110)
        at com.gnd.keepkey.funcoes.Exportar_Importar.backupDatabase (Export_Importar.java:87)
        at com.gnd.keepkey.funcoes.Exportar_Importar.access $ 000 (Export_Importar.java:42)
        at com.gnd.keepkey.funcoes.Export_Import $ 1.onClick (Export_Import.java:69)
W / System.err: at android.view.View.performClick (View.java:6259)
        at android.view.View $ PerformClick.run (View.java:24732)
        at android.os.Handler.handleCallback (Handler.java:789)
        at android.os.Handler.dispatchMessage (Handler.java:98)
        at android.os.Looper.loop (Looper.java:164)
        at android.app.ActivityThread.main (ActivityThread.java:6592)
        at java.lang.reflect.Method.invoke (Native Method)
W / System.err: at com.android.internal.os.Zygote $ MethodAndArgsCaller.run (Zygote.java:240)
        at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:769)

MikeT :

FileNotFoundException is likely due to the directory teste not existing, perhaps due to permissions.

Using :-

private void backupDatabase () throws IOException {
    String inFileName = "/data/data/com.gnd.example/databases/dados.db";
    File dbFile = new File (inFileName);
    FileInputStream fis = new FileInputStream (dbFile);

    String outFileName = Environment.getExternalStorageDirectory () + "/ example / backup / data.db";
    //<<<<<<<<<<< CODE ADDED >>>>>>>>>>
    File os = new File(outFileName); 
    if (!os.getParentFile().exists()) {
        os.getParentFile().mkdirs();
    }
    //<<<<<<<<<< END Of ADDED CODE >>>>>>>>>>
    OutputStream output = new FileOutputStream(os); //<<<<<<<<<< CHANGED
    byte [] buffer = new byte [1024];
    int length;
    while ((length = fis.read (buffer))> 0) {
        output.write (buffer, 0, length);
    }
    output.flush ();
    output.close ();
    fis.close ();
}

will create the directories if they do not exist (assuming permissions are correct)

Working Example :-

The following is a working app

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="aso.so56843045backup">
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
</manifest> 

• Note the <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/> (for earlier devices)

ExternalStoragePermissions.java

class ExternalStoragePermissions {

    public int API_VERSION = Build.VERSION.SDK_INT;
    private static final int REQUEST_EXTERNAL_STORAGE = 1;
    private static String[] PERMISSIONS_STORAGE = {

            //Manifest.permission.READ_EXTERNAL_STORAGE,
            Manifest.permission.WRITE_EXTERNAL_STORAGE
    };
    public static final String THISCLASS = ExternalStoragePermissions.class.getSimpleName();
    private static final String LOGTAG = "SW_ESP";

    public ExternalStoragePermissions() {}
    // Note call this method
    public static void verifyStoragePermissions(Activity activity) {
        int permission = ActivityCompat.checkSelfPermission(
                activity,
                Manifest.permission.WRITE_EXTERNAL_STORAGE);

        if(permission != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(
                    activity,
                    PERMISSIONS_STORAGE,
                    REQUEST_EXTERNAL_STORAGE
            );
        }
    }
}

• If permissions not given then the directories cannot be created resulting in FileNotFoundException.

DBHelper.java

public class DBHelper extends SQLiteOpenHelper {

    public static final String DBNAME = "dados.db";
    public static final int DBVERSION = 1;

    public DBHelper(Context context) {
        super(context, DBNAME, null, DBVERSION);
        this.getWritableDatabase();
    }

    @Override
    public void onCreate(SQLiteDatabase db) {

    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }
}

• A Very basic empty database (exception android_metadata table), enough to check backup.

MainActivity.java

public class MainActivity extends AppCompatActivity {

    DBHelper mDBHlpr;
    Button mBackup;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mBackup = this.findViewById(R.id.backup);
        mBackup.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                mDBHlpr.close();
                try {
                    backupDatabase();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        });
        ExternalStoragePermissions.verifyStoragePermissions(this);
        mDBHlpr = new DBHelper(this);
    }

    private void backupDatabase () throws IOException {
        FileInputStream fis = new FileInputStream (this.getDatabasePath("dados.db").getPath());
        String outFileName = Environment.getExternalStorageDirectory () + "/example/backup/" + String.valueOf(System.currentTimeMillis()) + "data.db";
        Log.d("OSFILEPATH",outFileName);
        File os = new File(outFileName);
        if (!os.getParentFile().exists()) {
            os.getParentFile().mkdirs();
        }
        OutputStream output = new FileOutputStream(os);
        byte [] buffer = new byte [1024];
        int length;
        while ((length = fis.read (buffer))> 0) {
            output.write (buffer, 0, length);
        }
        output.flush ();
        output.close ();
        fis.close ();
    }
}

Notes

• When first run after install permission will be requested for later devices (click allow).

• Backup has been named with a timestamp so multiple backups can exist.

• Database is closed, (this should cope with Android Pie+ wehere default is WAL mode, the close should empty (commit the changes) the -wal and -shm files, thus negating the need to backup the additional files).

Result