Document Information


Part I Introduction

1.  Overview

2.  Using the Tutorial Examples

Part II The Web Tier

3.  Getting Started with Web Applications

4.  Java Servlet Technology

What Is a Servlet?

Servlet Life Cycle

Handling Servlet Life-Cycle Events

Defining the Listener Class

Specifying Event Listener Classes

Handling Servlet Errors

Sharing Information

Using Scope Objects

Controlling Concurrent Access to Shared Resources

Accessing Databases

Initializing a Servlet

Writing Service Methods

Getting Information from Requests

Constructing Responses

Filtering Requests and Responses

Programming Filters

Programming Customized Requests and Responses

Specifying Filter Mappings

Invoking Other Web Resources

Including Other Resources in the Response

Transferring Control to Another Web Component

Accessing the Web Context

Maintaining Client State

Accessing a Session

Associating Objects with a Session

Notifying Objects That Are Associated with a Session

Session Management

Session Tracking

Finalizing a Servlet

Tracking Service Requests

Notifying Methods to Shut Down

Creating Polite Long-Running Methods

Further Information about Java Servlet Technology

5.  JavaServer Pages Technology

6.  JavaServer Pages Documents

7.  JavaServer Pages Standard Tag Library

8.  Custom Tags in JSP Pages

9.  Scripting in JSP Pages

10.  JavaServer Faces Technology

11.  Using JavaServer Faces Technology in JSP Pages

12.  Developing with JavaServer Faces Technology

13.  Creating Custom UI Components

14.  Configuring JavaServer Faces Applications

15.  Internationalizing and Localizing Web Applications

Part III Web Services

16.  Building Web Services with JAX-WS

17.  Binding between XML Schema and Java Classes

18.  Streaming API for XML

19.  SOAP with Attachments API for Java

Part IV Enterprise Beans

20.  Enterprise Beans

21.  Getting Started with Enterprise Beans

22.  Session Bean Examples

23.  A Message-Driven Bean Example

Part V Persistence

24.  Introduction to the Java Persistence API

25.  Persistence in the Web Tier

26.  Persistence in the EJB Tier

27.  The Java Persistence Query Language

Part VI Services

28.  Introduction to Security in the Java EE Platform

29.  Securing Java EE Applications

30.  Securing Web Applications

31.  The Java Message Service API

32.  Java EE Examples Using the JMS API

33.  Transactions

34.  Resource Connections

35.  Connector Architecture

Part VII Case Studies

36.  The Coffee Break Application

37.  The Duke's Bank Application

Part VIII Appendixes

A.  Java Encoding Schemes

B.  About the Authors



The Example Servlets

This chapter uses the Duke’s Bookstore application to illustrate the tasks involved in programming servlets. The source code for the bookstore application is located in the tut-install/javaeetutorial5/examples/web/bookstore1/ directory, which is created when you unzip the tutorial bundle (see Building the Examples).

Table 4-1 lists the servlets that handle each bookstore function. You can find these servlet classes in tut-install/javaeetutorial5/examples/web/bookstore1/src/java/com/sun/bookstore1/. 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 4-1 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.

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

  1. Perform all the operations described in Accessing Databases from Web Applications.

  2. In NetBeans IDE, select File→Open Project.

  3. In the Open Project dialog, navigate to:

  4. Select the bookstore1 folder.

  5. Select the Open as Main Project check box and the Open Required Projects check box.

  6. Click Open Project.

  7. In the Projects tab, right-click the bookstore1 project, and select Undeploy and Deploy.

  8. 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 tut-install/javaeetutorial5/examples/web/bookstore1/.

  2. Type ant. This command will spawn any necessary compilations, copy files to the tut-install/javaeetutorial5/examples/web/bookstore1/build/ directory, and create a WAR file and copy it to the tut-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, type 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:

  • A display-name element that specifies the name that tools use to identify the application.

  • A set of filter elements that identify servlet filters contained in the application.

  • A set of filter-mapping elements that identify which servlets will have their requests or responses filtered by the filters identified by the filter elements. A filter-mapping element can define more than one servlet mapping and more than one URL pattern for a particular filter.

  • A set of servlet elements that identify all the servlet instances of the application.

  • A set of servlet-mapping elements that map the servlets to URL patterns. More than one URL pattern can be defined for a particular servlet.

  • A set of error-page mappings that map exception types to an HTML page, so that the HTML page opens when an exception of that type is thrown by the application.

Troubleshooting Duke's Bookstore Database Problems

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

  • BookNotFoundException: Returned if a book can’t be located in the bookstore database. This will occur if you haven’t loaded the bookstore database with data or the server has not been started or has crashed. You can populate the database by running ant create-tables.

  • BooksNotFoundException: Returned if the bookstore data can’t be retrieved. This will occur if you haven’t loaded the bookstore database with data or if the database server hasn’t been started or it has crashed.

  • UnavailableException: Returned if a servlet can’t retrieve the web context attribute representing the bookstore. This will occur if the database server hasn’t been started.

Because you 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.