IndicatorsDatabaseHelper.java

package com.realtrackandroid.backend.indicators;

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

import android.content.Context;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;

public class IndicatorsDatabaseHelper extends SQLiteOpenHelper {
  private String dbPath;

  private static String DB_NAME = "indicators.sqlite";

  private SQLiteDatabase database;

  private final Context context;

  public IndicatorsDatabaseHelper(Context context) {
    super(context, DB_NAME, null, 1);
    dbPath = context.getDatabasePath(DB_NAME).getAbsolutePath();
    this.context = context;
  }

  /**
   * Creates a empty database on the system and rewrites it with your own database.
   * */
  public void createDataBase() throws IOException {
    boolean dbExist = checkDataBase();

    if (dbExist) {
      // do nothing - database already exists
    }
    else {
      this.getReadableDatabase();

      try {
        copyDataBaseToSystem();
      }
      catch (IOException e) {
        throw new Error("Error copying database");
      }
    }
  }

  /**
   * Check if the database already exist to avoid re-copying the file each time you open the
   * application.
   * 
   * @return true if it exists, false if it doesn't
   */
  private boolean checkDataBase() {
    SQLiteDatabase checkDB = null;

    try {
      checkDB = SQLiteDatabase.openDatabase(dbPath, null, SQLiteDatabase.OPEN_READONLY);

    }
    catch (SQLiteException e) {
      // database does't exist yet.
    }

    if (checkDB != null) {
      checkDB.close();
    }

    return checkDB != null ? true : false;
  }

  /**
   * Copies your database from your local assets-folder to the just created empty database in the
   * system folder, from where it can be accessed and handled. This is done by transfering
   * bytestream.
   * */
  private void copyDataBaseToSystem() throws IOException {
    // Open your local db as an input stream
    InputStream myInput = context.getAssets().open(DB_NAME);

    // Path to the just created empty db
    String outFileName = dbPath;

    // Open the empty db as the output stream
    OutputStream myOutput = new FileOutputStream(outFileName);

    // transfer bytes from the inputfile to the outputfile
    byte[] buffer = new byte[1024];
    int length;
    while ((length = myInput.read(buffer)) > 0) {
      myOutput.write(buffer, 0, length);
    }

    // Close the streams
    myOutput.flush();
    myOutput.close();
    myInput.close();

  }

  public void openDataBase() throws SQLException {
    // Open the database
    database = SQLiteDatabase.openDatabase(dbPath, null, SQLiteDatabase.OPEN_READONLY);
  }

  @Override
  public synchronized void close() {
    if (database != null)
      database.close();
    super.close();
  }

  @Override
  public void onCreate(SQLiteDatabase db) {
  }

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

}