The Example Servlets

This chapter uses the Duke's Bookstore application to illustrate the tasks involved in programming servlets. Table 3-1 lists the servlets that handle each bookstore function. Each programming task is illustrated by one or more servlets. For example, BookDetailsServlet illustrates how to handle HTTP GET requests, BookDetailsServlet and CatalogServlet show how to construct responses, and CatalogServlet illustrates how to track session information.

Table 3-1 Duke's Bookstore Example Servlets 
Enter the bookstore
Create the bookstore banner
Browse the bookstore catalog
Put a book in a shopping cart
Get detailed information on a specific book
Display the shopping cart
Remove one or more books from the shopping cart
Buy the books in the shopping cart
Send an acknowledgment of the purchase

The data for the bookstore application is maintained in a database and accessed through the database access class database.BookDBAO. The database package also contains the class Book which represents a book. The shopping cart and shopping cart items are represented by the classes cart.ShoppingCart and cart.ShoppingCartItem, respectively.

The source code for the bookstore application is located in the <INSTALL>/javaeetutorial5javaeetutorial5/examples/web/bookstore1/ directory, which is created when you unzip the tutorial bundle (see Building the Examples, page xxxi). To build the application, follow these steps:

  1. In a terminal window, go to <INSTALL>/javaeetutorial5/examples/web/bookstore1/.
  2. Run ant. This target will spawn any necessary compilations, copy files to the <INSTALL>/javaeetutorial5/examples/web/bookstore1/build/ directory, and create a WAR file and copy it to the <INSTALL>/javaeetutorial5/examples/web/bookstore1/dist/ directory.
  3. Start the Application Server.
  4. Perform all the operations described in Accessing Databases from Web Applications (page 54).

To deploy the example, run ant deploy. The deploy target outputs a URL for running the application. Ignore this URL, and instead use the one shown at the end of this section.

To learn how to configure the example, refer to the deployment descriptor (the web.xml file), which includes the following configurations:

To run the application, open the bookstore URL http://localhost:8080/bookstore1/bookstore.


The Duke's Bookstore database access object returns the following exceptions:

Because we have specified an error page, you will see the message

The application is unavailable. Please try later.  

If you don't specify an error page, the web container generates a default page containing the message

A Servlet Exception Has Occurred  

and a stack trace that can help you diagnose the cause of the exception. If you use errorpage.html, you will have to look in the server log to determine the cause of the exception.