Developing JavaServer Pages

The Email List Application

This topic introduces you to a simple web application that consists of one HTML page and one JavaServer Page, or JSP. Once you get the general idea of how this application works, you'll be ready to learn the specific skills that you need for developing JSPs.

The User Interface for the Application

Figure 1 shows the two pages that make up the user interface for the Email List application. The first page is an HTML page that asks the user to enter a first name, last name, and email address. Then, when the user clicks on the Submit button, the HTML page calls the JSP and passes the three user entries to that page.

Figure 1: The user interface for the application
The HTML page

The JSP

When the JSP receives the three entries, it could process them by checking them for validity, writing them to a file or database, and so on. In this simple application, though, the JSP just passes the three entries back to the browser so it can display the second page of this application. From this page, the user can return to the first page by clicking the Back button in the web browser or by clicking the Return button that's displayed on this page.

Building Blocks

As simple as this application is, you're going to learn a lot from it. In this chapter, you'll learn how to enhance this application so it uses regular Java classes to save the user entries in a text file. Then, in later chapters, you'll learn how to modify this application to illustrate other essential skills that apply to servlet and JSP programming.