Prentice Hall and Sun Microsystems. Personal use only; do not redistribute.

Chapter

he previous chapter showed you how to install the software you need

and how to set up your development environment. Now you want to

T

really write a few servlets. Good. This chapter shows you how, outlin 

ing the structure that almost all servlets follow, walking you through the steps

required to compile and execute a servlet, and giving details on how servlets

are initialized and when the various methods are called. It also introduces a

few general tools that you will find helpful in your servlet development.

2.1 Basic Servlet Structure

Listing 2.1 outlines a basic servlet that handles 

GET

 requests. 

GET

 requests, for

those unfamiliar with HTTP, are the usual type of browser requests for Web

pages. A browser generates this request when the user types a URL on the

address line, follows a link from a Web page, or submits an HTML form that

does not specify a 

METHOD

. Servlets can also very easily handle 

POST

 requests,

which are generated when someone submits an HTML form that specifies

METHOD="POST"

. For details on using HTML forms, see Chapter 16. 

To be a servlet, a class should extend 

HttpServlet

 and override 

doGet

 or

doPost

, depending on whether the data is being sent by 

GET

 or by 

POST

. If

you want the same servlet to handle both 

GET

 and 

POST

 and to take the same

action for each, you can simply have 

doGet

 call 

doPost

, or vice versa. 

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