contextlistener.java

来自「卡内基梅隆大学软件工程课件,很全面」· Java 代码 · 共 45 行

/*
 *
 * Copyright 2001 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * This software is the proprietary information of Sun Microsystems, Inc.  
 * Use is subject to license terms.
 * 
 */

package listeners;

import database.BookDB;
import javax.servlet.*;
import util.Counter;

public final class ContextListener
    implements ServletContextListener {
    private ServletContext context = null;

    public void contextInitialized(ServletContextEvent event) {
         context = event.getServletContext();
         
         try {
            BookDB bookDB = new BookDB();
            context.setAttribute("bookDB", bookDB);
         } catch (Exception ex) {
            context.log("Couldn't create bookstore database bean: " + ex.getMessage());
         }

         Counter counter = new Counter();
         context.setAttribute("hitCounter", counter);
         counter = new Counter();
         context.setAttribute("orderCounter", counter);
    }
      
    public void contextDestroyed(ServletContextEvent event) {
         context = event.getServletContext();
         BookDB bookDB = (BookDB)context.getAttribute("bookDB");
         bookDB.remove();
         context.removeAttribute("bookDB");
         context.removeAttribute("hitCounter");
         context.removeAttribute("orderCounter");
    }
}