connectionservlet.java

大量java源程序

/*
 * @(#)ConnectionServlet
 *
 * 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    04Apr98
 *
 */

package javaservlets.db;

import javax.servlet.*;
import javax.servlet.http.*;

/**
 * <p>This is a simple servlet that holds a global connection
 * pool.
 */

public class ConnectionServlet extends HttpServlet
{
  // Our connection pool.
  javaservlets.jdbc.ConnectionPool m_connectionPool;

  /**
    * <p>Get a JDBC connection from the pool
    *
    * @return JDBC connection
    */
  public java.sql.Connection getConnection() throws Exception
    {
      java.sql.Connection con = null;
      if (m_connectionPool != null) {
        con = m_connectionPool.getConnection();
      }
      return con;
    }

  /**
    * <p>Closes the given JDBC connection
    *
    * @param con JDBC Connection
    */
  public void close(java.sql.Connection con)
    {
      if (m_connectionPool != null) {
        m_connectionPool.close(con);
      }
    }
  /**
    * <p>Initialize the servlet. This is called once when the
    * servlet is loaded. It is guaranteed to complete before any
    * requests are made to the servlet
    *
    * @param cfg Servlet configuration information
    */

  public void init(ServletConfig cfg)
    throws ServletException
    {
      super.init(cfg);

      // Create our connection pool
      m_connectionPool = new javaservlets.jdbc.ConnectionPool();

      // Initialize the connection pool. This will start all
      // of the connections as specified in the connection
      // pool configuration file
      try {
        m_connectionPool.initialize();
          //("javaservlets.db.FastEmployeeList.cfg");
      }
      catch (Exception ex) {
        // Convert the exception
        ex.printStackTrace();
        throw new ServletException
          ("Unable to initialize connection pool");
      }
    }

  /**
    * <p>Destroy the servlet. This is called once when the servlet
    * is unloaded.
    */

  public void destroy()
    {
      // Tear down our connection pool if it was created
      if (m_connectionPool != null) {
        m_connectionPool.destroy();
      }
      super.destroy();
    }

}