Chapter 7. Handling Web Form Data in Servlets and JSPs

Introduction

Every web developer is familiar with the scenario in which a client fills out an HTML form and then submits the inserted information to a server-side program for processing. Some of these programs use the HTTP request method POST to deliver the data to the server-side program. The POST method sends the data to the server in the body of the request, rather than as a query string appended to a URL (as in the GET method). For example, consider the HTML form tag in Example 7-1.

Example 7-1. HTML form tag set up for posting data
<form method=POST action="/project/controller">

<b>User Name:</b> <input type="text" name="username" 
size="20">  <br><br>

<b>Department:</b> <input type="text" name="department" 
size="15"><br><br>

<b>Email:</b> <input type="text" name="email" 
size="15"><br><br>

<input type="submit" value="Submit">

</form>

When the client submits this form information, the top of the client’s request text looks like this:

POST /project/controller HTTP/1.1
Accept: image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/msword, 
application/vnd.ms-powerpoint, application/vnd.ms-excel, application/pdf, */*
Referer: http://localhost:8080/project/login.jsp
Accept-Language: en-us
Content-Type: application/x-www-form-urlencoded

Beneath this text, after a few more headers, the body of the request carries the submitted data:

username=Bruce+W+Perry&password=bw_p1968

JSPs and servlets make parsing the POST data quite transparent ...

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