How to avoid form resubmission -servlet,jsp-

Question

when i logged in using the post method, the form data will be sent to owner-controller servlet and finally redirect to viewStaff.jsp page.

the problem is, if i'm using request dispatcher, whenever i reload the viewStaff.jsp page, the browser will ask me to confirm form resubmission. where am I doing wrong? however if i use response.sendRedirect method, i can't pass some necessary data to viewStaff.jsp page, unless if i'm using session.

therefore, how do i prevent confirm form resubmission if i'm using request dispatcher?

//this is the method that will handle the request and response object, and forward it to viewStaff.jsp

public void viewStaff(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
        RequestDispatcher rd = request.getRequestDispatcher("/owners/viewStaff.jsp");
        rd.forward(request, response);
    }

//this is the method that will handle login error. if there are no error, then it will call the viewStaff method

public void login(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
        String username = "";
        String password = "";
        
        String username_err = "";
        String password_err = "";
        
        username = request.getParameter("username");
        password = request.getParameter("password");
        
        if(username.isEmpty()) {
            username_err = "please enter username";
        }
        
        if(password.isEmpty()) {
            password_err = "please enter password";
        }
        
        if(!username.isEmpty()&&!password.isEmpty()) {
            viewStaff(request, response);
        } else {
            request.setAttribute("username_err", username_err);
            request.setAttribute("password_err", password_err);
            RequestDispatcher rd = request.getRequestDispatcher("/owners/login.jsp");
            rd.forward(request, response);
        }
    }

//this is the actual post method

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        PrintWriter out = response.getWriter();
        String action = "";
        action = request.getParameter("action");
        
        if(action.equals("login")) {
            login(request,response);
        }
    
    }

//this is my login.jsp

<c:set var="username_err" value="${requestScope.username_err}" />
<c:set var="password_err" value="${requestScope.password_err}" />
<c:set var="username" value="${param.username}" />
<c:set var="password" value="${param.password}" />
<main class="form-signin">
    <form action="owner-controller?action=login" method="POST">
        <h1 class="h3 mb-3 fw-normal">
            Please sign in |
            <p class="fw-lighter">owner</p>
        </h1>

        <div class="form-floating">
            <input type="text" name="username"
                class="form-control <c:if test="${not empty username_err}">is-invalid</c:if> "
                value="${param.username}" id="floatingInput"
                placeholder="Username"> <label for="floatingInput">Username</label>
        </div>
        <span style="color: red;">
            <!-- username error here -->
        </span>

        <div class="form-floating">
            <input type="password" name="password" class="form-control <c:if test="${not empty password_err}">is-invalid</c:if>"
                id="floatingPassword" placeholder="Password"> <label
                for="floatingPassword">Password</label>
        </div>

        <span style="color: red;">
            <!-- password error here -->
        </span>

        <div class="checkbox mb-3">
            <label> <input type="checkbox" value="remember-me">
                Remember me
            </label>
        </div>
        <button class="w-100 btn btn-lg btn-primary" type="submit">Sign
            in</button>
    </form>
    <a href="owner-controller?action=login">click here to invoke GET method</a>
</main>

enter image description here

i did try using session attribute and it works, i don't have to confirm form resubmission. but somehow i want to know why request dispatcher does not work?