import java.sql.*;
import javax.servlet.*;
import java.io.*;
import javax.servlet.http.*;
import java.util.*;
 
/******
* 
*  DatabaseServlet: 
*    A superclass for servlets that use a database.
*    The database and the connections are specified
*    in a configuration file (variable confile) using
*    parameters:
*      dbDriver
*      dbServer
*      dbLogin 
*      dbPassword
*    This class supports only one database and one user account.
*    connections are not pooled.
*    
* -- Harri Laine 5.1.2006
*/
 
 
public class DatabaseServlet extends HttpServlet {
   // parameters for database connection

   protected static String dbDriver =null;
   protected static String dbServer = null;
   protected static String dbLogin = null;
   protected static String dbPassword = null;
   protected static boolean driverLoaded =false;
   // you may include here other initialization paramerers that 
   // apply for all servlets

   
   public void init (ServletConfig config) throws ServletException  {
      super.init(config);
      if (!driverLoaded) { 
         String cFile = config.getServletContext().getInitParameter("confile");   
         // confile must be defined in deployment description
         Properties p = new Properties();
         try {
            p.load(new FileInputStream(cFile));
            dbDriver = (String) p.get("dbDriver");
            dbServer = (String) p.get("dbServer");
            dbLogin  = (String) p.get("dbLogin");
            dbPassword = (String) p.get("dbPassword");
            // load the driver class              
            Class.forName(dbDriver);
            driverLoaded =true;
         }
         catch (Exception f) {
                f.printStackTrace();
         }
      }
   }

   /*****
   /*   Open database connection
   */
   public static Connection getConnection() {
      // returns a database connection or null if setting up the 
      // connection fails
      Connection con=null;
      try { 
         con= DriverManager.getConnection(dbServer,dbLogin,dbPassword);
         // here is a proper place for adjustments
         // language, data format, commit behaviour, timeout, etc.
      } 
      catch (SQLException ignored) {}
      return con;
   }   
  
   /****
   /*  Close database connection
   */
   public static void closeConnection(Connection con) {
      try {
         con.close();
      } catch (SQLException ignored) {}
   }

}