• JW's Most Read
• Editor's Choice

Most read:

• MapReduce programming with Hadoop
• Open source Java projects: JOGL
• iBATIS, Hibernate, and JPA
• Web development with Wicket, Part 3
• Hello, OSGi, Part 1: Bundles for beginners

Popular archives:

• Advanced form processing using JSP (2000)
• J2EE object-caching frameworks (2004)
• The Maven 2 POM demystified (2006)

JavaWorld's new look is here!
We've upgraded the site with a fresh look-and-feel, improved topical navigation, better search, new features, and expanded community platform. Learn more about the changes to JavaWorld.

class DBManager {
  // DBManager is a singleton class.
  private static DBManager instance;
  private String driver;
  private String url;
  private String user;
  private String password;
  private boolean delay;
  private Connection connection;
  private Statement statement;
  private PreparedStatement insert;
  private PreparedStatement find;
  private PreparedStatement delete;
  private PreparedStatement update;
  private PreparedStatement all;
  static DBManager getInstance() {
    if (instance == null) {
      instance = new DBManager();
    }
    return instance;
  }
  private DBManager() {
    // Get parameters from runtime properties.
    // This allows us to switch to different JDBC databases
    // without changing the application code.
    Properties properties = ContactManager.getProperties();
    driver =
      properties.getProperty("driver", "com.pointbase.me.jdbc.jdbcDriver");
    url =
      properties.getProperty("url", "jdbc:pointbase:micro:pbdemo");
    user =
      properties.getProperty("user", "PBPUBLIC");
    password =
      properties.getProperty("password", "PBPUBLIC");
    delay =
      properties.getProperty("delayread","true").equals("true");
    connect();
  }
  private void connect() {
    try {
      // Load the driver class.
      Class.forName(driver);
      // If the database doesn't exist, create a new database.
      connection = DriverManager.getConnection(url, user, password);
      // Create template statement objects.
      statement = connection.createStatement();
      createStatement();
      // If the database is newly created, load the schema.
      boolean newdb=initDatabase();
      // Load sample data for the new tables.
      if(newdb) {
         SampleDataCreator.insert(connection);
      }
    } catch (Exception e) {
      e.printStackTrace();
      System.exit(1);
    }
  }
  void disconnect() {
    try {
      connection.commit();
      statement.close();
      insert.close();
      find.close();
      delete.close();
      update.close();
      all.close();
      connection.close();
      System.exit(0);
    } catch (Exception e) {
      e.printStackTrace();
      System.exit(1);
    }
  }
  // Create the table and load the schema.
  private boolean initDatabase() {
    try {
      String sql = "CREATE TABLE NameCard (ID INT PRIMARY KEY, "+
        "Name VARCHAR(254), Company VARCHAR(254), Title VARCHAR(254), "+
        "Address1 VARCHAR(254), Address2 VARCHAR(254), "+
        "Phone VARCHAR(254), Email VARCHAR(254), "+
        "Picture Binary(1000000))";
      // If the table already exists, this will throw an exception.
      statement.executeUpdate(sql);
      // This means the database already exists.
      return true;
    } catch (SQLException e) {
      // Ignore the error - the table already exists, which is good
      // so we don't need to add demo data later on.
      return false;
    }
  }
  // Create statement templates.
  private void createStatement() {
    try {
      insert = connection.prepareStatement(
        "INSERT INTO NameCard (ID, Name, Company, Title, Address1, "+
        "Address2, Phone, Email, Picture) "+
        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)");
      find = connection.prepareStatement(
        "SELECT * FROM NameCard WHERE (Name LIKE ?) "+
        "AND (Company LIKE ?) AND (Title LIKE ?) "+
        "AND ((Address1 LIKE ?) OR (Address2 LIKE ?)) "+
        "AND (Phone LIKE ?) AND (Email LIKE ?)");
      delete = connection.prepareStatement(
        "DELETE FROM NameCard WHERE ID = ?");
      update = connection.prepareStatement(
        "UPDATE NameCard SET ID=?, Name=?, Company=?, Title=?, "+
        "Address1=?, Address2=?, Phone=?, Email=?, Picture=? "+
        "WHERE ID = ?");
      all = connection.prepareStatement(
        "SELECT ID, Name, Company, Title, Address1, Address2, "+
        "Phone, Email FROM NameCard");
    } catch (SQLException e) {
      e.printStackTrace();
    }
  }
  
  // Other methods.
}