HTTP state management is implemented in Java SE through the 
 class.
A <code>CookieHandler</code> object provides a callback mechanism to provide 
an HTTP state management 
policy implementation in the HTTP protocol handler. That is, URLs that use
HTTP as the protocol, <code>new URL("http://java.sun.com")</code> for example, 
will use the HTTP protocol handler. This protocol handler calls back
to the <code>CookieHander</code> object, if set, to handle the state management.
<p>
The <code>CookieHandler</code> class is an abstract class that has two pairs 
of related methods. The first pair, <code>getDefault()</code> and 
<code>setDefault(cookieHandler)</code>, are static methods that enable you to 
discover the current handler that is installed and to install your own handler. 
<p>
No default handler is installed, and installing a handler is done on a 
system-wide basis. For applications running within a secure environment, that is, 
they have a security manager installed, you must have special permission to get 
and set the handler. For more information, see
.
<p>
The second pair of related methods, <code>put(uri, responseHeaders)</code> and 
<code>get(uri, requestHeaders)</code>, enable you to set and get all the applicable 
cookies to and from a cookie cache for the specified URI in the response/request headers, 
respectively. These methods are abstract, and a concrete implementation
of a <code>CookieHandler</code> must provide the implementation.
<p>
Java Web Start and Java Plug-in have a default <code>CookieHandler</code> installed. 
However, if you are running a stand-alone application and want to enable HTTP state
management, you must set a system-wide handler. The next two pages 
in this lesson show you how to do so.