Servlets: Processing Form Parameters
Problem
You want to process the data from an HTML form in a servlet.
Solution
Use the request object’s
getParameter( )
method.
Discussion
Each uniquely named INPUT element in the FORM on the HTML page makes
an entry in the request object’s list of
parameters. These can be obtained as an enumeration, but more
commonly you request just one. Figure 18-2 shows a
simple form that asks you how many random numbers you want generated,
and makes up that many for you.
Figure 18-2. Random numbers HTML page
When I type the number 8 into the field and press the “Get Yours” button, I see the screen shot in Figure 18-3.
Figure 18-3. Random numbers servlet output
How does it work? The program obviously consists of both an HTML page and a Java servlet. The HTML page appears in Example 18-3; notice the FORM entry and the INPUT field.
Example 18-3. IntsServlet.htm
<HTML> <HEAD><TITLE>Random Numbers Page</TITLE></HEAD> <BODY BGCOLOR="white"> <H1>Random Numbers Page</H1> <P>This site will let you pick some random numbers for Lottery, lucky number or other purposes, all electronically.</P> <FORM METHOD=POST ACTION="/servlets/IntsServlet"> <H4>How Many Numbers Do You Want Today?</H4> <INPUT NAME=howmany SIZE=2> (default is 5) <BR> <INPUT TYPE="SUBMIT" VALUE="Get YOURS!"> ...
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