Database Reference
In-Depth Information
Some session-related operations shown in
sess_track.jsp
can be done using tags from
the JSTL tag library, which provides a
sessionScope
variable for accessing the implicit
JSP session object. The following script,
sess_track2.jsp
, uses that variable. One differ‐
ence in approach is that
sess_track.jsp
terminates the session by calling
session.inva
lidate()
, but the
sessionScope
variable provides no access to that method. Instead,
sess_track2.jsp
terminates the session by deleting the session contents, causing the ses‐
sion to restart with the next client request:
<%-
-
sess_track2
.
jsp
:
session
request
counting
/
timestamping
demonstration
--
%>
<%@
page
import
=
"java.util.*"
%>
<%@
taglib
prefix
=
"c"
uri
=
"http://java.sun.com/jsp/jstl/core"
%>
<c:if
test=
"${empty sessionScope.count}"
>
<c:set
var=
"count"
scope=
"session"
value=
"0"
/>
</c:if>
<c:set
var=
"count"
scope=
"session"
value=
"${sessionScope.count+1}"
/>
<%
ArrayList
timestamp
=
(
ArrayList
)
session
.
getAttribute
(
"timestamp"
);
if
(
timestamp
==
null
)
timestamp
=
new
ArrayList
();
// add current timestamp to timestamp array, store result in session
timestamp
.
add
(
new
Date
());
session
.
setAttribute
(
"timestamp"
,
timestamp
);
%>
<html>
<head><title>
JSP Session Tracker
</title></head>
<body>
<p>
This session has been active for
<c:out
value=
"${sessionScope.count}"
/>
requests.
</p>
<p>
The requests occurred at these times:
</p>
<ol>
<c:forEach
items=
"${sessionScope.timestamp}"
var=
"t"
>
<li><c:out
value=
"${t}"
/></li>
</c:forEach>
</ol>
<p>
Reload page to send next request.
</p>
<%-
-
has
session
limit
of
10
requests
been
reached
?
--
%>
<c:if
test=
"${sessionScope.count ge 10}"
>
<c:remove
var=
"count"
scope=
"session"
/>
<c:remove
var=
"timestamp"
scope=
"session"
/>
</c:if>
