Android Open Source - GameTimer Database Layer

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From Project

Back to project page GameTimer.

License

The source code is released under:

Apache License

Java Source Code

package com.solidnw.gametimer.database;
//from w ww.j  a v  a  2 s  .  c  om
import java.io.File;
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;


/**
 * The DatabaseLayer class provides the lowest level interaction with the database.
 * The database is placed in the asset directory of the project.
 * It places the database in the default directory for databases on the phone (/data/data/...)
 * 
 * @author SickSta
 * @since 14:57:28 - 27.10.2012
 * @project AndroBlocks
 */
public class DatabaseLayer extends SQLiteOpenHelper
{
  // TODO: Rewrite this class so it does not load a predefined database from assets
  // but rather creates one itself (without content?)
  // ===========================================================
  // Constants
  // ===========================================================
  private static final String DB_NAME      = "database";
  private static final String DB_EXTENSION  = ".db";
  private static final int   DB_VERSION    = 1;


  // ===========================================================
  // Fields
  // ===========================================================
  private Context     context;
  private SQLiteDatabase  database;
  private String       dbPath;
  
  // ===========================================================
  // Constructors
  // ===========================================================
  public DatabaseLayer(Context context)
  {
    super(context, DatabaseLayer.DB_NAME, null, DatabaseLayer.DB_VERSION);
    this.context  = context;
    this.dbPath    = "/data/data/"+ getContext().getPackageName() + "/databases/" + DatabaseLayer.DB_NAME;
    
    try
    {
      this.createDatabase();
      this.openDatabase();
    }
    catch(IOException ioe)
    {
      System.out.println("IOException in DatabaseLayer: " + ioe.getMessage());
    }
    catch(SQLException sqle)
    {
      System.out.println("SQLException in DatabaseLayer: " + sqle.getMessage());
    }
  }

  // ===========================================================
  // Methods for/from SuperClass/Interfaces
  // ===========================================================
  public void onCreate(SQLiteDatabase db)
  {
    // Nothing to do here
  }

  public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
  {
    // Nothing to do here
  }

  public synchronized void close()
  {
    if(database != null)
    {
      database.close();
    }
    super.close();
  }
  
  // ===========================================================
  // Methods
  // ===========================================================
  /**
   * Creates the database on the system. If it already exists it does nothing.
   * 
   * @throws IOException
   */
  public void createDatabase() throws IOException
  {
    boolean dbExists = this.checkDatabase();
    if(dbExists)
    {
      // Do nothing because database already exists
    }
    else
    {
      // this creates an empty database on the system
      getReadableDatabase();
      try
      {
        copyDatabase();
      }
      catch(IOException ioe)
      {
        throw new IOException(ioe);
      }
      
    }
  }
  
  public void openDatabase() throws SQLException
  {
    this.database = SQLiteDatabase.openDatabase(getDbPath(), null, SQLiteDatabase.OPEN_READWRITE);
  }
  
  /**
   * Checks whether the database exists or not
   * @return true if the database already exists
   */
  private boolean checkDatabase()
  {
    SQLiteDatabase db  = null;
    boolean check     = false;
    try
    {
      String path = getDbPath();
      
      // A lot of errors get generated here, but you can ignore them
      db = SQLiteDatabase.openDatabase(path, null, SQLiteDatabase.OPEN_READONLY);
    }
    catch(SQLiteException e)
    { 
      // Nothing do to here
    }
    if(db != null)
    {
      check = true;
      db.close();
    }
    return check;
  }
  
  /**
   * Copies the database from the assets-directory of the project onto the device.
   * It uses an byte-stream so no information is lost.
   * 
   * @throws IOException
   */
  private void copyDatabase() throws IOException
  {
    // Standard directory for databases. Maybe rethink this for devices with small memory and put it on the sd-card
    File f = new File("/data/data/"+ getContext().getPackageName() + "/databases/");
    if (f.exists() != true)
    {
      f.mkdir();
    }

    InputStream is    = getContext().getAssets().open(DB_NAME + DB_EXTENSION);
    String newDbName  = getDbPath();
    OutputStream os    = new FileOutputStream(newDbName);
    
    byte[] buffer     = new byte[1024];
    int length;
    while ( (length = is.read(buffer)) > 0)
    {
      os.write(buffer, 0, length);
    }

    //Close the streams
    os.flush();
    os.close();
    is.close();     
  }

  // ===========================================================
  // Getter & Setter
  // ===========================================================
  /**
   * @return the context
   */
  private Context getContext()
  {
    return this.context;
  }
  
  /**
   * @return the dbPath
   */
  private String getDbPath()
  {
    return this.dbPath;
  }
  
  /**
   * @return the database
   */
  public SQLiteDatabase getDatabase()
  {
    return database;
  }

  /**
   * @param context
   *            the context to set
   */
  private void setContext(Context context)
  {
    this.context = context;
  }
  
  // ===========================================================
  // Inner and Anonymous Classes
  // ===========================================================
}

Java Source Code List

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