The DatabaseConnector class.

gistfile1.java

import java.io.File;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public final class DatabaseConnector {
  private static DatabaseConnector instance;

  private static String useMySQL = null;
  // Deployment note: Replace with a real server name.
  private static final String MYSQL_URI = "jdbc:mysql://somedatabase.com:3306/";
  private static final String SQLITE_URI = "jdbc:sqlite:";
  private static final String DB_USER = "meetuser";
  private static final String DB_PASS = "meetpass";

  private Connection connection;

  private DatabaseConnector() throws SQLException {
    try {
      Class.forName("org.sqlite.JDBC");
      Class.forName("com.mysql.jdbc.Driver");
    } catch (Exception e) {
      throw new RuntimeException(e);
    }

    String DB_URI = (useMySQL != null) ? (MYSQL_URI + useMySQL) :
        (SQLITE_URI +
        new File(System.getProperty("user.home"), "limecat.sqlite").toString());
    System.out.println("Using DB " + DB_URI);
    connection = DriverManager.getConnection(DB_URI, DB_USER, DB_PASS);
    // Don't bother being to transactionally correct for this lab.
    connection.setAutoCommit(true);
  }

  public static DatabaseConnector getInstance() throws SQLException {
    if (instance == null)
      instance = new DatabaseConnector();
    return instance;
  }

  public Connection getConnection() {
    return connection;
  }

  public boolean isMySQL() {
    return useMySQL != null;
  }

  /* Call this before calling getInstance() to use a remote MySQL server
  instead. Everone else has access to this database as well! */
  public static void setUseMySQL(String dbName) {
    if (instance != null && !dbName.equals(DatabaseConnector.useMySQL)) {
      throw new IllegalStateException(
          "Can't call setUseMySQL() after getInstance() has been called.");
    }
    DatabaseConnector.useMySQL = dbName;
  }
}