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());
 
     }
 
 
 }