Java Reference
In-Depth Information
CookieManager
Java 5 includes an abstract
java.net.CookieHandler
class that defines an API for stor‐
ing and retrieving cookies. However, it does not include an implementation of that
abstract class, so it requires a lot of grunt work. Java 6 fleshes this out by adding a concrete
java.net.CookieManager
subclass of
CookieHandler
that you can use. However, it is
not turned on by default. Before Java will store and return cookies, you need to enable
it:
CookieManager
manager
=
new
CookieManager
();
CookieHandler
.
setDefault
(
manager
);
If all you want is to receive cookies from sites and send them back to those sites, you're
done. That's all there is to it. After installing a
CookieManager
with those two lines of
code, Java will store any cookies sent by HTTP servers you connect to with the
URL
class,
and will send the stored cookies back to those same servers in subsequent requests.
However, you may wish to be a bit more careful about whose cookies you accept. You
can do this by specifying a
CookiePolicy
. Three policies are predefined:
•
CookiePolicy.ACCEPT_ALL
All cookies allowed
•
CookiePolicy.ACCEPT_NONE
No cookies allowed
•
CookiePolicy.ACCEPT_ORIGINAL_SERVER
Only first party cookies allowed
For example, this code fragment tells Java to block third-party cookies but accept first-
party cookies:
CookieManager
manager
=
new
CookieManager
();
manager
.
setCookiePolicy
(
CookiePolicy
.
ACCEPT_ORIGINAL_SERVER
);
CookieHandler
.
setDefault
(
manager
);
That is, it will only accept cookies for the server that you're talking to, not for any server
on the Internet.
If you want more fine-grained control, for instance to allow cookies from some known
domains but not others, you can implement the
CookiePolicy
interface yourself and
override the
shouldAccept()
method:
public
boolean
shouldAccept
(
URI
uri
,
HttpCookie
cookie
)
Example 6-1
shows a simple
CookiePolicy
that blocks cookies from
.gov
domains, but
allows others.
Example 6-1. A cookie policy that blocks all .gov cookies but allows others
import
java.net.*
;
public
class
NoGovernmentCookies
implements
CookiePolicy
{
