Cookies in servlet
- 1. Cookies in Servlet Prof. Neeraj Bhargava Kapil Chauhan Department of Computer Science School of Engineering & Systems Sciences MDS University, Ajmer
- 2. Cookies in Servlet A cookie is a small piece of information that is persisted between the multiple client requests. A cookie has a name, a single value, and optional attributes such as a comment, path and domain qualifiers, a maximum age, and a version number.
- 3. How Cookie works By default, each request is considered as a new request. In cookies technique, we add cookie with response from the servlet. So cookie is stored in the cache of the browser. After that if request is sent by the user, cookie is added with request by default. Thus, we recognize the user as the old user.
- 4. Cont.. There are three steps involved in identifying returning users − Server script sends a set of cookies to the browser. For example name, age, or identification number etc. Browser stores this information on local machine for future use. When next time browser sends any request to web server then it sends those cookies information to the server and server uses that information to identify the user.
- 5. Types of Cookie There are 2 types of cookies in servlets. Non-persistent cookie Persistent cookie
- 6. Cont… Non-persistent cookie It is valid for single session only. It is removed each time when user closes the browser. Persistent cookie It is valid for multiple session . It is not removed each time when user closes the browser. It is removed only if user logout or signout.
- 7. Advantage of Cookies Simplest technique of maintaining the state. Cookies are maintained at client side.
- 8. Disadvantage of Cookies It will not work if cookie is disabled from the browser. Only textual information can be set in Cookie object.
- 9. Example public class FirstServlet extends HttpServlet { public void doPost(HttpServletRequest request, HttpServletResponse response){ try{ response.setContentType("text/html"); PrintWriter out = response.getWriter(); String n=request.getParameter("userName"); out.print("Welcome "+n); Cookie ck=new Cookie("u",n); response.addCookie(ck); out.print("<form action='servlet2' method='post'>"); out.print("<input type='submit' value='go'>"); out.print("</form>"); out.close(); }catch(Exception e){System.out.println(e);} } }
- 10. Assignment Explain cookies in java script with suitable example.