ShowCookies.java  Servlet that displays all cookies that arrived in current request. Uses the ServletUtilities  class. 

package cwp;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

/** Sets six cookies: three that apply only to the current
 *  session (regardless of how long that session lasts)
 *  and three that persist for an hour (regardless of
 *  whether the browser is restarted).
 *

* Taken from Core Web Programming Java 2 Edition * from Prentice Hall and Sun Microsystems Press, * . * May be freely used or adapted. */ public class SetCookies extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { for(int i=0; i<3; i++) { // Default maxAge is -1, indicating cookie // applies only to current browsing session. Cookie cookie = new Cookie("Session-Cookie-" + i, "Cookie-Value-S" + i); response.addCookie(cookie); cookie = new Cookie("Persistent-Cookie-" + i, "Cookie-Value-P" + i); // Cookie is valid for an hour, regardless of whether // user quits browser, reboots computer, or whatever. cookie.setMaxAge(3600); response.addCookie(cookie); } response.setContentType("text/html"); PrintWriter out = response.getWriter(); String title = "Setting Cookies"; out.println (ServletUtilities.headWithTitle(title) + "\n" + "

" + title + "

\n" +
       "There are six cookies associated with this page.\n" +
       "To see them, visit the\n" +
       "\n" +
       "ShowCookies servlet.\n" +
       "

\n" + "Three of the cookies are associated only with the\n" + "current session, while three are persistent.\n" + "Quit the browser, restart, and return to the\n" + "ShowCookies servlet to verify that\n" + "the three long-lived ones persist across sessions.\n" + ""); } } ServletUtilities.java package cwp; import javax.servlet.*; import javax.servlet.http.*; /** Some simple time savers. Note that most are static methods. *

* Taken from Core Web Programming Java 2 Edition * from Prentice Hall and Sun Microsystems Press, * . * May be freely used or adapted. */ public class ServletUtilities { public static final String DOCTYPE = ""; public static String headWithTitle(String title) { return(DOCTYPE + "\n" + "\n" + "\n"); } /** Read a parameter with the specified name, convert it * to an int, and return it. Return the designated default * value if the parameter doesn't exist or if it is an * illegal integer format. */ public static int getIntParameter(HttpServletRequest request, String paramName, int defaultValue) { String paramString = request.getParameter(paramName); int paramValue; try { paramValue = Integer.parseInt(paramString); } catch(NumberFormatException nfe) { // null or bad format paramValue = defaultValue; } return(paramValue); } /** Given an array of Cookies, a name, and a default value, * this method tries to find the value of the cookie with * the given name. If there is no cookie matching the name * in the array, then the default value is returned instead. */ public static String getCookieValue(Cookie[] cookies, String cookieName, String defaultValue) { if (cookies != null) { for(int i=0; i<cookies.length; i++)="" {="" cookie="" if="" (cookiename.equals(cookie.getname()))="" return(cookie.getvalue());="" }="" return(defaultvalue);="" **="" given="" an="" array="" of="" cookies="" and="" a="" name,="" this="" method="" tries="" *="" to="" find="" return="" the="" from="" that="" has="" name.="" there="" is="" no="" matching="" name="" in="" array,="" null="" returned.="" public="" static="" getcookie(cookie[]="" cookies,="" string="" cookiename)="" (cookies="" !="null)" for(int="" i="0;" i<cookies.length;="" return(cookie);="" return(null);="" string,="" replaces="" all="" occurrences="" '<'="" with="" '<',="" '="">' with * '>', and (to handle cases that occur inside attribute * values), all occurrences of double quotes with * '"' and all occurrences of '&' with '&'. * Without such filtering, an arbitrary string * could not safely be inserted in a Web page. */ public static String filter(String input) { StringBuffer filtered = new StringBuffer(input.length()); char c; for(int i=0; i<input.length(); i++)="" {="" c="input.charAt(i);" if="" (c="=" '<')="" filtered.append("<");="" }="" else="" '="">') { filtered.append(">"); } else if (c == '"') { filtered.append("""); } else if (c == '&') { filtered.append("&"); } else { filtered.append(c); } } return(filtered.toString()); } }