Re: Web browser in java

From:
=?ISO-8859-1?Q?Arne_Vajh=F8j?= <arne@vajhoej.dk>
Newsgroups:
comp.lang.java.programmer
Date:
Wed, 09 Jan 2013 21:31:45 -0500
Message-ID:
<50ee2819$0$294$14726298@news.sunsite.dk>
On 1/8/2013 8:10 AM, lipska the kat wrote:

On 08/01/13 12:19, Roma Asnani wrote:

Want to create a web browser but unable to handle cookies can any one
help?
I get some source from this link
http://www.apl.jhu.edu/~hall/java/Swing-Tutorial/Swing-Tutorial-JEditorPane.html

but it display a simple browser but has no cookies or session handling.


Firstly it is not the browser that maintains a session it is the server.


It needs info from the client to do so.

When you make a request for a web page your browser looks in the place
where it stores cookies (if you are writing a web browser this can be
anywhere you like, a browser usually writes cookies to disk) and adds
any cookies it finds that match the URL you are requesting to the
request. Only then will it send the request

So, you need a way of searching your cookie store, finding any cookies
that 'belong' to the URL you are requesting and adding the resulting
cookies to the request before you send it.


Cookies with session id should never be stored on disk.

When your request hits the server, you access the cookies by extracting
them from the request, actually if you are using a Java servlet
container like Tomcat you don't need to bother with explicitly managing
session cookies, If a session exists (in other words if a valid session
cookie was sent by the browser) Tomcat will retrieve the session using
the contents of the cookie to 'lookup' the session in it's session
store. If a session doesn't exist or if it has timed out, Tomcat will
make a new one, create a cookie with a lookup key in it (amongst other
things) and add the cookie to the response.


Depends. JSP pages do so. Servlets do not.

If you are making a request to a server that understands how to use
cookies to maintain state then all you have to do is extract cookies
from a response to your original request, store them somewhere safe, and
add them to your next request, the server will take care of the rest.

The simplified sequence of events goes something like this

1. Make a request to foo.bar.com

Before you actually send the request but after you know the target

2. Search your browser cookie store for any cookies that belong to
foo.bar.com, if you find them, add them to the request.

3. send the request

4. When the server replies, parse the response and extract any cookies
written by the server, one of these is probably your session key. Save
them to your cookie store.

5. make a new request to foo.bar.com adding the session cookie to the
request.

bingo! you have a session


You can skip #2 (unless you need other info than
session that are stored in cookies).

But I would let #5 add all cookies retrieved in #4,
because they are most likely all needed (if not then
there were no reason to set them).

Arne

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