/*

  * Copyright 2000-2004 The Apache Software Foundation.

  * 

  * Licensed under the Apache License, Version 2.0 (the "License");

  * you may not use this file except in compliance with the License.

  * You may obtain a copy of the License at

  * 

  *      http://www.apache.org/licenses/LICENSE-2.0

  * 

  * Unless required by applicable law or agreed to in writing, software

  * distributed under the License is distributed on an "AS IS" BASIS,

  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  * See the License for the specific language governing permissions and

  * limitations under the License.

  */

 package org.apache.commons.scaffold.http;

 import java.io.IOException;

 import javax.servlet.ServletException;

 import org.apache.commons.logging.Log;

 import org.apache.commons.logging.LogFactory;

 import org.apache.commons.scaffold.sql.ConnectionAdaptor;

 import org.apache.commons.scaffold.sql.ServletAdaptor;

 /**

  * Initialize a <code>ConnectionAdaptor</code> for this application.

  * <p>

  * The servlet itself is <b>not</b> involved in managing the connection.

  * The ConnectionAdaptor is a standalone object.

  * This servlet simply provides a means to initialize and load a

  * ConnectionAdaptor for use by your application.

  * <p>

  * This servlet can be configured to use an alternate adaptor or

  * adaptor key using initialization parameters:

  * <p>

  * <b>adaptor</b> The default adaptor is

  * <code>org.apache.scaffold.sql.ConnectionAdaptor</code>.

  * Any sublcass of ConnectionAdaptor can be specified instead.

  * <p>

  * <b>adaptor.key</b> The default adaptor key is <code>DATA_SOURCE</code>.

  * Another key can be specified instead. This is the attribute to use

  * when looking up the datasource in JNDI, the servlet context, or

  * whatever.

  * <p>

  * To use the Struts generic connection pool, specify the adaptor as

  * <code>org.apache.scaffold.sql.ServletAdaptor</code> and the

  * adaptor.key as <code>org.apache.struts.action.DATA_SOURCE</code>

  * <p>

  * To use the Resin connection pool, specify the <b>res-ref-name</b>

  * in the Resin conf as the <b>adaptor.key</b>.

  * <p>

  * To use Poolman without JNDI, use the Poolman adaptor in the

  * sql package, and specify the dbName from the poolman.xml as the

  * <b>adaptor.key</b>

  *

  * @see org.apache.scaffold.sql.ConnectionAdaptor

  * @see org.apache.scaffold.sql.Servletdaptor

  * @see org.apache.scaffold.sql.PoolmanAdaptor

  * 

  * @author Ted Husted

  * @author Steve Raeburn 

  * 

  */

 public class ConnectionServlet extends ResourceServlet {

         // ------------------------------------------------------- Class variables

         /**

          * Commons logging instance

          */

         private static Log log = LogFactory.getLog(ResourceServlet.class);

         /**

      * Default parameter for setting a custom adaptor type

      * in the servlet configuration.

      */

     private static String ADAPTOR_PARAMETER = "adaptor";

     /**

      * Default type to use if parameter not set

      * ["org.apache.scaffold.sql.ConnectionAdaptor"].

      */

     private static String ADAPTOR_DEFAULT =

         "org.apache.commons.scaffold.sql.ConnectionAdaptor";

     /**

      * Default parameter for setting the default attribute

      * name, or key, used to retrieve the datasource.

      * <p>

      * For the Struts generic connection pool, you would set

      * this to "org.apache.struts.action.DATA_SOURCE"

      * [Action.DATA_SOURCE_KEY].

      */

     private static String ADAPTOR_KEY = "adaptor.key";

     /**

      * Field to hold our instance of the connection adaptor.

      * Can be initialized to another ConnectionAdaptor at startup.

      */

     private static ConnectionAdaptor adaptor;

         // ------------------------------------------------------ Logging Messages    

         /**

          * Message for verbose logging.

          */

         private static String ADAPTOR_LOADING_EVENT = 

         "Loading ConnectionAdaptor";

         /**

          * Message to log if connector initialization fails.

          */

         private static String ADAPTOR_FAILED_EVENT =

                 "*** ConnectionAdaptor failed to load: ";

     // -----------------------------------------------------------------------

     /**

      * Initialize the ConnectionAdaptor for this application.

      * <p>

      * An alternate ConnectionAdaptor can be specified in the servlet config

      * by specifying the class type as the <b>adaptor</b> initialization

      * parameter.

      *

      * @exception IOException if an input/output error is encountered

      * @exception ServletException if we cannot initialize these resources

      */

     protected void initDefault() throws IOException, ServletException {

         super.initDefault();

         if (log.isDebugEnabled()) {

             log(ADAPTOR_LOADING_EVENT);

         }

             // Check for an adaptor parameter

         String adaptorClass =

             getInitString(ADAPTOR_PARAMETER,ADAPTOR_DEFAULT);

             // Create the default or custom adaptor

         try {

             adaptor = (ConnectionAdaptor)

                 Class.forName(adaptorClass).newInstance();

         }

         catch (Throwable t) {

             log.error(ADAPTOR_FAILED_EVENT,t);

             t.printStackTrace();

             throw new ServletException(t);

         }

             // Check for an adaptor key

         String key = getInitString(ADAPTOR_KEY,null);

         if (null!=key) adaptor.setKey(key);

             // ** kludge alert **

             // If its a servlet adaptor, give it a servlet reference

         if (adaptor instanceof ServletAdaptor) {

                 // Give adaptor access to servlet context.

             ServletAdaptor s = (ServletAdaptor) adaptor;

             s.setServlet(this);

         }

     }

 } // end ConnectionServlet