indy.java~1~

大量java源程序

/*
 * @(#)Indy
 *
 * Copyright (c) 1998 Karl Moss. All Rights Reserved.
 *
 * You may study, use, modify, and distribute this software for any
 * purpose provided that this copyright notice appears in all copies.
 *
 * This software is provided WITHOUT WARRANTY either expressed or
 * implied.
 *
 * @author  Karl Moss
 * @version 1.0
 * @date    17Apr98
 *
 */

package javaservlets.tunnel;

import java.sql.*;

/**
  * <p>Implements the IndyInterface to provide query capabilities
  * into the Indianapolis 500 database.
  */

public class Indy implements IndyInterface
{
  // The JDBC Connection
  Connection m_connection = null;

  // A prepared statement to use to query the database
  PreparedStatement m_ps = null;

  /**
    * <p>Connects to the database.
    *
    * @return True if the database connection was established
    */
  public boolean connect()
    {
      boolean rc = false;

      try {

        // Load the Bridge
        Class.forName("sun.jdbc.odbc.JdbcOdbcDriver").newInstance();

        // Connect to the Access database
        m_connection =
          DriverManager.getConnection("jdbc:odbc:MyAccessDataSource");

        // Go ahead and create a prepared statement
        m_ps = m_connection.prepareStatement
          ("SELECT Year, Driver, AvgSpeed from IndyWinners " +
           "WHERE Year = ?");

        rc = true;
      }
      catch (Exception ex) {
        ex.printStackTrace();
      }

      return rc;
    }

  /**
    * <p>Closes the database connection
    */
  public void close()
    {
      // Close the connection if it was opened
      if (m_connection != null) {
        try {
          m_connection.close();
        }
        catch (SQLException ex) {
          ex.printStackTrace();
        }
        m_connection = null;
      }
    }

  /**
    * <p>Given the year return the corresponding Indianapolis
    * 500 record
    *
    * @param year Year of the race
    * @return Indy 500 record or null if not found
    */
  public IndyRecord query(int year)
    {
      IndyRecord record = null;

      try {

        // Set the year parameter
        m_ps.setInt(1, year);

        // Execute the query
        ResultSet rs = m_ps.executeQuery();

        // Make sure a record exists
        if (rs.next()) {

          // Create a new IndyRecord object
          record = new IndyRecord();

          // Set the values
          record.year = rs.getInt(1);
          record.driver = rs.getString(2);
          record.speed = rs.getDouble(3);
        }
        rs.close();
      }
      catch (SQLException ex) {
        ex.printStackTrace();
        record = null;
      }

      return record;
    }

}