How to manage login and logout sessions.please give me the code in java if any...

...one knows? i have index.jsp which containd a login form with UID and password.when the user click on submit it goes to verify.jsp check for valid user and if so he will be redirected to welcome.jspwhen the user click on signout he should be redirected to index.jsp if the user click on back button he should not get the welcome.jsp


Please give me the answer.