Compile the servlets. Next, copy them to the appropriate directory, and update the web.xml
file, as previously described. Then, perform these steps to test this example:
1. Start Tomcat, if it is not already running.
2. Display AddCookie.htm in a browser.
3. Enter a value for MyCookie.
4. Submit the web page.
After completing these steps, you will observe that a feedback message is displayed by the
Next, request the following URL via the browser:
Observe that the name and value of the cookie are displayed in the browser.
In this example, an expiration date is not explicitly assigned to the cookie via the setMaxAge( )
method of Cookie. Therefore, the cookie expires when the browser session ends. You can
experiment by using setMaxAge( ) and observe that the cookie is then saved to the disk on
the client machine.
Session Tracking
HTTP is a stateless protocol. Each request is independent of the previous one. However, in
some applications, it is necessary to save state information so that information can be collected
from several interactions between a browser and a server. Sessions provide such a mechanism.
A session can be created via the getSession( ) method of HttpServletRequest. An
HttpSession object is returned. This object can store a set of bindings that associate names with
objects. The setAttribute( ), getAttribute( ), getAttributeNames( ), and removeAttribute( )
methods of HttpSession manage these bindings. It is important to note that session state is
shared among all the servlets that are associated with a particular client.
The following servlet illustrates how to use session state. The getSession( ) method gets the
current session. A new session is created if one does not already exist. The getAttribute( )
method is called to obtain the object that is bound to the name "date". That object is a Date
object that encapsulates the date and time when this page was last accessed. (Of course, there
is no such binding when the page is first accessed.) A Date object encapsulating the current
date and time is then created. The setAttribute( ) method is called to bind the name "date"
to this object.
public class DateServlet extends HttpServlet {
public void doGet(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
Search WWH :
Custom Search
Previous Page
Java SE 6 Topic Index
Next Page
Java SE 6 Bookmarks