/*
* Copyright (c) JForum Team
* All rights reserved.
*
* Redistribution and use in source and binary forms,
* with or without modification, are permitted provided
* that the following conditions are met:
*
* 1) Redistributions of source code must retain the above
* copyright notice, this list of conditions and the
* following disclaimer.
* 2) Redistributions in binary form must reproduce the
* above copyright notice, this list of conditions and
* the following disclaimer in the documentation and/or
* other materials provided with the distribution.
* 3) Neither the name of "Rafael Steil" nor
* the names of its contributors may be used to endorse
* or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT
* HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
* THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
* OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
* IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE
*
* This file creation date: 25/08/2004 23:03:14
* The JForum Project
* http://www.jforum.net
*/
package net.jforum;
import java.sql.Connection;
import net.jforum.util.preferences.ConfigKeys;
import net.jforum.util.preferences.SystemGlobals;
import org.apache.log4j.Logger;
/**
* Base class for all database connection implementations that
* may be used with JForum.
* Default implementations are <code>PooledConnection</code>, which
* is the defeault connection pool implementation, and <code>SimpleConnection</code>,
* which opens a new connection on every request.
*
* @author Rafael Steil
* @version $Id: DBConnection.java,v 1.14 2006/08/23 02:24:06 rafaelsteil Exp $
*/
public abstract class DBConnection
{
private static final Logger logger = Logger.getLogger(DBConnection.class);
protected boolean isDatabaseUp;
private static DBConnection instance;
/**
* Creates an instance of some <code>DBConnection </code>implementation.
*
* @return <code>true</code> if the instance was successfully created,
* or <code>false</code> if some exception was thrown.
*/
public static boolean createInstance()
{
try {
instance = (DBConnection)Class.forName(SystemGlobals.getValue(
ConfigKeys.DATABASE_CONNECTION_IMPLEMENTATION)).newInstance();
}
catch (Exception e) {
logger.warn("Error creating the database connection implementation instance. " + e);
e.printStackTrace();
return false;
}
return true;
}
/**
* Gets the current <code>DBConnection</code> implementation's instance
*
* @return DBConnection
*/
public static DBConnection getImplementation()
{
return instance;
}
/**
* Checks if database connection is up.
*
* @return <code>true</code> if a connection to the database
* was successfully created, or <code>false</code> if not.
*/
public boolean isDatabaseUp()
{
return this.isDatabaseUp;
}
/**
* Inits the implementation.
* Connection pools may use this method to init the connections from the
* database, while non-pooled implementation can provide an empty method
* block if no other initialization is necessary.
* <br>
* Please note that this method will be called just once, at system startup.
*
* @throws Exception
*/
public abstract void init() throws Exception;
/**
* Gets a connection.
* Connection pools' normal behaviour will be to once connection
* from the pool, while non-pooled implementations will want to
* go to the database and get the connection in time the method
* is called.
*
* @return Connection
*/
public abstract Connection getConnection();
/**
* Releases a connection.
* Connection pools will want to put the connection back to the pool list,
* while non-pooled implementations should call <code>close()</code> directly
* in the connection object.
*
* @param conn The connection to release
*/
public abstract void releaseConnection(Connection conn);
/**
* Close all open connections.
*
* @throws Exception
*/
public abstract void realReleaseAllConnections() throws Exception;
}