How to create database from Assets in Android using GreenDao ORM library

Question

I am using GreenDao orm library for creating database, it works good with the First sample for Creating Database, from within the code.

Now the problem is I can't find any documentation or anything related to the Database copying from Assets Folder to the databases inside memory.

Answer 1

The accepted answer provides a solution but it's only partially correct. Check out the class I posted below. This is an extension of greenDao's OpenHelper class. Below that is an example of it's use and how you can use it instead of OpenHelper or DevOpenHelper to manage the copy of your sqlite database.

package com.example;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import com.example.R;
import com.example.DaoMaster.OpenHelper;

public class DatabaseOpenHelper extends OpenHelper {

    private Context context;

    private SQLiteDatabase sqliteDatabase;

    private static String DB_PATH;

    private static String DB_NAME;

    public DatabaseOpenHelper(Context context, String name, CursorFactory factory) {
        super(context, name, factory);
        this.context = context;
        this.DB_NAME = name;
        this.DB_PATH = context.getString(R.string.DB_PATH);
        try {
            createDataBase();
        } catch (Exception ioe) {
            throw new Error("Unable to create database");
        }
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // TODO Auto-generated method stub

    }

    /** Open Database for Use */
    public void openDatabase() {
        String databasePath = DB_PATH + DB_NAME;
        sqliteDatabase = SQLiteDatabase.openDatabase(databasePath, null,
                (SQLiteDatabase.OPEN_READWRITE));
    }

    /** Close Database after use */
    @Override
    public synchronized void close() {
        if ((sqliteDatabase != null) && sqliteDatabase.isOpen()) {
            sqliteDatabase.close();
        }
        super.close();
    }

    /** Get database instance for use */
    public SQLiteDatabase getSqliteDatabase() {
        return sqliteDatabase;
    }

    /** Create new database if not present */
    public void createDataBase() {
        SQLiteDatabase sqliteDatabase = null;

        if (databaseExists()) {
            /* Check for Upgrade */
        } else {
            /* Database does not exists create blank database */
            sqliteDatabase = this.getReadableDatabase();
            sqliteDatabase.close();

            copyDataBase();
        }
    }

    /** Check Database if it exists */
    private boolean databaseExists() {
        SQLiteDatabase sqliteDatabase = null;
        try {
            String databasePath = DB_PATH + DB_NAME;
            sqliteDatabase = SQLiteDatabase.openDatabase(databasePath, null,
                    SQLiteDatabase.OPEN_READONLY);
        } catch (SQLiteException e) {
            e.printStackTrace();
        }

        if (sqliteDatabase != null) {
            sqliteDatabase.close();
        }
        return sqliteDatabase != null ? true : false;
    }

    /**
     * Copy existing database file in system
     */
    public void copyDataBase() {

        int length;
        byte[] buffer = new byte[1024];
        String databasePath = DB_PATH + DB_NAME;

        try {
            InputStream databaseInputFile = this.context.getAssets().open(DB_NAME+".sqlite");
            OutputStream databaseOutputFile = new FileOutputStream(databasePath);

            while ((length = databaseInputFile.read(buffer)) > 0) {
                databaseOutputFile.write(buffer, 0, length);
                databaseOutputFile.flush();
            }
            databaseInputFile.close();
            databaseOutputFile.close();

        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}

So here is an example of it's usage:

DatabaseOpenHelper helper = new DatabaseOpenHelper(this, "db", null);
db = helper.getWritableDatabase();
daoMaster = new DaoMaster(db);
daoSession = daoMaster.newSession();