Redirecting to home page if user is already logged in [duplicate]

Answer 1

For your help i have written an example and executed the code in my machine.

In servlet page, in doPost:

String username = request.getParameter("username");
String password = request.getParameter("password");
boolean isCredentialValid = validateCredentials(username, password);
String nextPage ="";
HttpSession session = request.getSession(true);
if(isCredentialValid){
    nextPage = "home.jsp";
    session.setAttribute("isLoggedIn", "true");
}else{
    request.setAttribute("error", "Either username or password is invalid.");
    nextPage ="login.jsp";
}
RequestDispatcher rd = request.getRequestDispatcher(nextPage);
rd.forward(request, response);

in login.jsp

   

    ${error}
    

     UserName : 
    

     Password :