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192

Chapter 8 Handling Cookies

Listing 8.4 LongLivedCookie.java 

package coreservlets;

import javax.servlet.http.*;

/** Cookie that persists 1 year. Default Cookie doesn t

 *  persist past current session.

 */

public class LongLivedCookie extends Cookie {

  public static final int SECONDS_PER_YEAR = 60*60*24*365;

  public LongLivedCookie(String name, String value) {

    super(name, value);

    setMaxAge(SECONDS_PER_YEAR);

  }

}

reads the user choices from the HTML front end and forwards them to the

appropriate search engine. In addition, the 

CustomizedSearchEngines

servlet returns to the client cookies that store the search values. Then, when

the user comes back to the front end servlet at a later time (even after quit 

ting the browser and restarting), the front end page is initialized with the val 

ues from the previous search. 

To accomplish this customization, the front end is dynamically generated

instead of coming from a static HTML file (see Listing 8.6 for the source

code and Figure 8 4 for the result). The front end servlet reads the cookie

values and uses them for the initial values of the HTML form fields. Note

that it would not have been possible for the front end to return the cookies

directly to the client. That's because the search selections aren't known until

the user interactively fills in the form and submits it, which cannot occur until

after the servlet that generated the front end has finished executing.

This example uses the 

LongLivedCookie

 class, shown in the previous sec 

tion, for creating a 

Cookie

 that automatically has a long term expiration date,

instructing the browser to use it beyond the current session. 

Second edition of this book: www.coreservlets.com; Sequel: www.moreservlets.com.

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