Now that you've mastered the basics, it's time to bring out thebig iron. This week, The JSP Files explores the various techniquesavailable to "maintain state" on a JSP-based Web site. Learn about theCookie and Session objects, find out how to build a cookie-based hitcounter, and read about a simple yet effective way of protecting sensitiveWeb pages with the Session object.
So that takes care of writing a cookie - but how about reading it? Here'sthe code.
// declare some variables
Cookie cookieCounter = null;
// the cookie you want
String cookieName = "counter";
int cookieFound = 0;
// a few more useful variables
// get an array of all cookies available on client
Cookie cookies = request.getCookies();
// iterate through array looking for your cookie
for(int i=0; i<cookies.length; i++)
cookieCounter = cookies[i];
cookieFound = 1;
Before you can read the cookie, you need to find it on the client's harddrive. Since JSP does not currently allow you to directly locate andidentify the cookie by name, you need to iterate through all availablecookies until you find the one you're looking for. In the example above,the "for" loop does just that; if and when it finds the cookie, it sets the"cookieFound" variable to 1 and breaks out of the loop.
At this point, the cookie is stored in the Cookie object "cookieCounter".You can then use the getValue() object method to get the current value ofthe cookie variable, and use it in your script.
// if found
if(cookieFound == 1)
// get the counter value as string
tempString = cookieCounter.getValue();
// convert it to a number
count = Integer.parseInt(tempString);
// increment it
// back to a string
tempString = Integer.toString(count);
// store it in the cookie for future use
// set some other attributes
// send cookie to client