Java Reference
In-Depth Information
of a Web site provided entirely via servlets, the shopping cart example from the
previous chapter will be re-implemented.
Example
The initial page will be renamed
ShoppingCart
X
.html
. The only change required
for this page is the address for the form's
ACTION
attribute. Instead of specifying a
servlet called
Selection
, this will now specify a JSP called
Selection.jsp
:
<FORM METHOD=POST ACTION="
Selection.jsp
">
The code for
Selection.jsp
is shown below, with JSP-specifi c content shown in
bold. Note that, if the 'Checkout' option is selected by the user, control is now re-
directed to another JSP (viz.,
Checkout.jsp
), rather than to servlet
Checkout
. Note
also how use is made of the implicit object
session
to store the value of the current
product, without the necessity for creating a
Session
object explicitly (as was the
case in the
selection
servlet).
In the servlet-only version of this application, control is then passed to a
Weight
servlet. Since this servlet's activities consist entirely of background processing and
re-direction to the next appropriate page, with no Web page output being generated,
this is an ideal opportunity for keeping the servlet. There are one or two minor
changes that need to be made to this servlet (as will be identifi ed shortly) and the
modifi ed servlet will be named
WeightX
. The reference to this servlet is also shown
in bold type below.
<!-- Selection.jsp -->
<HTML>
<HEAD>
<TITLE>
<%= currentProduct %>
</TITLE>
<STYLE>
body{text-align=center; color=blue;}
</STYLE>
</HEAD>
<BODY>
<%
String currentProduct;
currentProduct = request.getParameter("Product");
if (currentProduct.equals("Checkout"))
response.sendRedirect("Checkout.jsp");
else
session.setAttribute(
"currentProd",currentProduct);
%>
<H1><P STYLE=”color:red”>
<%= currentProduct %>
</P></H1>
<BR><BR><BR>
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