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JSP Cookies Example

                          

This tutorial shows how to handle cookies in JSP pages. In this tutorial you will learn how to add cookies through jsp page and then show the value of the same cookie in another JSP page.

Let's understand the cookies. Cookies are short pieces of data sent by web servers to the client browser. The cookies are saved to clients hard disk in the form of small text file. Cookies helps the web servers to identify web users, by this way server tracks the user. Cookies pay very important role in the session tracking.

Cookie Class

In JSP cookie are the object of the class javax.servlet.http.Cookie. This class is used to creates a cookie, a small amount of information sent by a servlet to a Web browser, saved by the browser, and later sent back to the server. A cookie's value can uniquely identify a client, so cookies are commonly used for session management. 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.

The getCookies() method of the request object returns an array of Cookie objects. Cookies can be constructed using the following code:

Cookie(java.lang.String name, java.lang.String value)

Cookie objects have the following methods.

Method

Description

getComment()

Returns the comment describing the purpose of this cookie, or null if no such comment has been defined.

getMaxAge()

Returns the maximum specified age of the cookie.

getName()

Returns the name of the cookie.

getPath()

Returns the prefix of all URLs for which this cookie is targeted.

getValue()

Returns the value of the cookie.

setComment(String)

If a web browser presents this cookie to a user, the cookie's purpose will be described using this comment.

setMaxAge(int)

Sets the maximum age of the cookie. The cookie will expire after that many seconds have passed. Negative values indicate the default behavior: the cookie is not stored persistently, and will be deleted when the user web browser exits. A zero value causes the cookie to be deleted

setPath(String)

This cookie should be presented only with requests beginning with this URL.

setValue(String)

Sets the value of the cookie. Values with various special characters (white space, brackets and parentheses, the equals sign, comma, double quote, slashes, question marks, the "at" sign, colon, and semicolon) should be avoided. Empty values may not behave the same way on all browsers.

Example Using Cookies

No we will write code in JSP file to set and then display the cookie.

Create Form

Here is the code of the form (cookieform.jsp) which prompts the user to enter his/her name.

<%@ page language="java" %>
<html>
<head>
<title>Cookie Input Form</title>
</head>
<body>
<form method="post" action="setcookie.jsp">
<p><b>Enter Your Name: </b><input type="text" name="username"><br>
<input type="submit" value="Submit">

</form>

</body>

Above form prompts the user to enter the user name. User input are posted to the setcookie.jsp file, which sets the cookie. Here is the code of setcookie.jsp file:

<%@ page language="java" import="java.util.*"%>
<%
String username=request.getParameter("username");
if(username==null) username="";


Date now = new Date();
String timestamp = now.toString();
Cookie cookie = new Cookie ("username",username);
cookie.setMaxAge(365 * 24 * 60 * 60);
response.addCookie(cookie);


%>

<html>
<head>
<title>Cookie Saved</title>
</head>
<body>
<p><a href="showcookievalue.jsp">Next Page to view the cookie value</a><p>

</body>

Above code sets the cookie and then displays a link to view cookie page. Here is the code of display cookie page (showcookievalue.jsp):

<%@ page language="java" %>
<%
String cookieName = "username";
Cookie cookies [] = request.getCookies ();
Cookie myCookie = null;
if (cookies != null)
{
for (int i = 0; i < cookies.length; i++) 
{
if (cookies [i].getName().equals (cookieName))
{
myCookie = cookies[i];
break;
}
}
}

%>
<html>
<head>
<title>Show Saved Cookie</title>
</head>
<body>


<%
if (myCookie == null) {
%>
No Cookie found with the name <%=cookieName%>
<%
} else {
%> 
<p>Welcome: <%=myCookie.getValue()%>.
<%
}
%>
</body>

When user navigates to the above the page, cookie value is displayed.

 

                          

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