2009/05/20 - Apache Shale has been retired.

 /*

  * Licensed to the Apache Software Foundation (ASF) under one or more

  * contributor license agreements.  See the NOTICE file distributed with

  * this work for additional information regarding copyright ownership.

  * The ASF licenses this file to you 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.

  *

  * $Id: ApplicationListener.java 464373 2006-10-16 04:21:54Z rahul $

  */

 package org.apache.shale.examples.mailreader;

 import java.io.BufferedInputStream;

 import java.io.BufferedOutputStream;

 import java.io.File;

 import java.io.FileOutputStream;

 import java.io.InputStream;

 import javax.faces.model.SelectItem;

 import javax.servlet.ServletContext;

 import javax.servlet.ServletContextEvent;

 import javax.servlet.ServletContextListener;

 import javax.servlet.ServletException;

 import org.apache.commons.logging.Log;

 import org.apache.commons.logging.LogFactory;

 import org.apache.struts.apps.mailreader.dao.impl.memory.MemoryUserDatabase;

 /**

  * <p><code>ServletContextListener</code> that initializes and finalizes the

  * persistent storage of User and Subscription information for the Struts

  * Demonstration Application, using an in-memory database backed by an

  * XML file.</p>

  *

  * <p><strong>IMPLEMENTATION WARNING</strong> - If this web application is run

  * from a WAR file, or in another environment where reading and writing of the

  * web application resource is impossible, the initial contents will be copied

  * to a file in the web application temporary directory provided by the

  * container.  This is for demonstration purposes only - you should

  * <strong>NOT</strong> assume that files written here will survive a restart

  * of your servlet container.</p>

  */

 public final class ApplicationListener implements ServletContextListener {

     // ------------------------------------------------------ Manifest Constants

     /**

      * <p>Appication scope attribute key under which the in-memory

      * version of our database is stored.</p>

      */

     public static final String DATABASE_KEY = "database";

     /**

      * <p>Application scope attribute key under which the valid

      * selection items for the protocol property is stored.</p>

      */

     public static final String PROTOCOLS_KEY = "protocols";

     // ------------------------------------------------------ Instance Variables

     /**

      * <p>The <code>ServletContext</code> for this web application.</p>

      */

     private ServletContext context = null;

     /**

      * The {@link MemoryUserDatabase} object we construct and make available.

      */

     private MemoryUserDatabase database = null;

     /**

      * Logging output for this plug in instance.

      */

     private Log log = LogFactory.getLog(this.getClass());

     // ------------------------------------------------------------- Properties

     /**

      * The web application resource path of our persistent database

      * storage file.

      */

     private String pathname = "/WEB-INF/database.xml";

     public String getPathname() {

         return (this.pathname);

     }

     public void setPathname(String pathname) {

         this.pathname = pathname;

     }

     // ------------------------------------------ ServletContextListener Methods

     /**

      * <p>Gracefully shut down this database, releasing any resources

      * that were allocated at initialization.</p>

      *

      * @param event ServletContextEvent to process

      */

     public void contextDestroyed(ServletContextEvent event) {

         log.info("Finalizing memory database plug in");

         if (database != null) {

             try {

                 database.close();

             } catch (Exception e) {

                 log.error("Closing memory database", e);

             }

         }

         context.removeAttribute(DATABASE_KEY);

         context.removeAttribute(PROTOCOLS_KEY);

         database = null;

         context = null;

     }

     /**

      * <p>Initialize and load our initial database from persistent storage.</p>

      *

      * @param event The context initialization event

      *

      * @exception ServletException if we cannot configure ourselves correctly

      */

     public void contextInitialized(ServletContextEvent event) {

         log.info("Initializing memory database plug in from '" +

                  pathname + "'");

         // Remember our associated ServletContext

         this.context = event.getServletContext();

         // Construct a new database and make it available

         database = new MemoryUserDatabase();

         try {

             String path = calculatePath();

             if (log.isDebugEnabled()) {

                 log.debug(" Loading database from '" + path + "'");

             }

             database.setPathname(path);

             database.open();

         } catch (Exception e) {

             log.error("Opening memory database", e);

             throw new IllegalStateException("Cannot load database from '" +

                                             pathname + "': " + e);

         }

         context.setAttribute(DATABASE_KEY, database);

         // Cache the selection items for protocols

         SelectItem protocols[] = new SelectItem[2];

         protocols[0] = new SelectItem("imap", "IMAP Protocol");

         protocols[1] = new SelectItem("pop3", "POP3 Protocol");

         context.setAttribute(PROTOCOLS_KEY, protocols);

     }

     // -------------------------------------------------------- Private Methods

     /**

      * Calculate and return an absolute pathname to the XML file to contain

      * our persistent storage information.

      *

      * @exception Exception if an input/output error occurs

      */

     private String calculatePath() throws Exception {

         // Can we access the database via file I/O?

         String path = context.getRealPath(pathname);

         if (path != null) {

             return (path);

         }

         // Does a copy of this file already exist in our temporary directory

         File dir = (File)

             context.getAttribute("javax.servlet.context.tempdir");

         File file = new File(dir, "struts-example-database.xml");

         if (file.exists()) {

             return (file.getAbsolutePath());

         }

         // Copy the static resource to a temporary file and return its path

         InputStream is =

             context.getResourceAsStream(pathname);

         BufferedInputStream bis = new BufferedInputStream(is, 1024);

         FileOutputStream os =

             new FileOutputStream(file);

         BufferedOutputStream bos = new BufferedOutputStream(os, 1024);

         byte buffer[] = new byte[1024];

         while (true) {

             int n = bis.read(buffer);

             if (n <= 0) {

                 break;

             }

             bos.write(buffer, 0, n);

         }

         bos.close();

         bis.close();

         return (file.getAbsolutePath());

     }

 }