jsp从servlet中获取的值为空

		System.out.println("进入servlet");
		UserServiceImpl us=new UserServiceImpl();
		List<User> user_list=us.getAllUser();
		request.setAttribute("userlists",user_list);
		response.sendRedirect("user/user_list.jsp");

		System.out.println("进入servlet");
		UserServiceImpl us=new UserServiceImpl();
		List<User> user_list=us.getAllUser();
		request.setAttribute("userlists",user_list);
		request.getRequestDispatcher("user/user_list.jsp").forward(request, response);