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Cookies on the server

Of course, using cookies for client-server communication requires additional logic on the server. Server-

side technologies such as JSP, ASP.NET, and PHP provide built-in functionality to read, write, and other-

wise manipulate cookies. Using JavaScript and one of these server-side languages, you can pass data

back and forth using cookies.

JSP

Java Server Pages (JSP) provides a very easy interface for handling cookies. The

request

object, which is

instantiated automatically when a JSP is executed, has a method called

getCookies()

that returns an

array of

objects. Each

object has the following methods (from the Javadoc documentation):

getComment()

— Returns the comment describing the purpose of this cookie, or

null

if the

cookie has no comment

getDomain()

— Returns the domain name set for this cookie

getMaxAge()

— Returns the maximum age of the cookie, specified in seconds; by default, -1

indicates the cookie will persist until browser shutdown.

getName()

— Returns the name of the cookie

getPath()

— Returns the path on the server to which the browser returns this cookie

getSecure()

— Returns

true

if the browser is sending cookies only over a secure protocol, or

false

if the browser can send cookies using any protocol.

getValue()

— Returns the value of the cookie

getVersion()

— Returns the version of the protocol this cookie complies with

setComment(String purpose)

— Specifies a comment that describes a cookie’s purpose.

setDomain(String pattern)

— Specifies the domain within which this cookie should be

presented

setMaxAge(int expiry)

— Sets the maximum age of the cookie in seconds

setPath(String uri)

- Specifies a path for the cookie to which the client should return the

setSecure(boolean flag)

— Indicates to the browser whether the cookie should only be

sent using a secure protocol, such as HTTPS or SSL

setValue(String newValue)

— Assigns a new value to a cookie after the cookie is created

setVersion(int v)

— Sets the version of the cookie protocol this cookie complies with

To get a specific cookie, it’s also necessary to create a function to iterate through each cookie to deter-

mine which one you want:

<%!

public static Cookie getCookie(HttpServletRequest request, String name) {

Cookie[] cookies = request.getCookies();

if (cookies != null) {

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Client-Server Communication

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