求问，我在servlet中首先转发到一个jsp页面进行输出，然后怎么才能重定向跳转到另一个jsp呢？

Question

User user = (User) request.getSession().getAttribute("user");
if(user==null){
request.setAttribute("message", "请先登陆！！，3秒后自动跳转！");
request.getRequestDispatcher("/message.jsp").forward(request, response);
try {
Thread.sleep(3000);

            response.sendRedirect("/client/register.jsp");
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }

        之后就抛出异常了，如下：
        java.lang.IllegalStateException: Cannot call sendRedirect() after the response has been committed

Answer 1