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 
Function
Servlet
Enter the bookstore
BookStoreServlet
Create the bookstore banner
BannerServlet
Browse the bookstore catalog
CatalogServlet
Put a book in a shopping cart
CatalogServlet,
BookDetailsServlet
Get detailed information on a specific book
BookDetailsServlet
Display the shopping cart
ShowCartServlet
Remove one or more books from the shopping cart
ShowCartServlet
Buy the books in the shopping cart
CashierServlet
Send an acknowledgment of the purchase
ReceiptServlet

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).

To deploy and run the application using NetBeans 5.5, follow these steps:

  1. Perform all the operations described in Accessing Databases from Web Applications.
  2. In NetBeans 5.5, select FileRight ArrowOpen Project Folder.
  3. In the Open Project dialog, navigate to:
  4. <INSTALL>/javaeetutorial5/examples/web/

  5. Select the bookstore1 folder.
  6. Select the Open as Main Project checkbox and the Open Required Projects checkbox.
  7. Click Open Project Folder.
  8. In the Projects tab, right-click the bookstore1 project, and select Deploy Project.
  9. To run the application, open the bookstore URL http://localhost:8080/bookstore1/bookstore.

To deploy and run the application using Ant, follow these steps:

  1. In a terminal window, go to <INSTALL>/javaeetutorial5/examples/web/bookstore1/.
  2. Run the command 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 Creating a Data Source in the Application Server.
  5. 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 in the next step.
  6. To run the application, open the bookstore URL http://localhost:8080/bookstore1/bookstore.

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

Troubleshooting

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.