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