关于controller注解应用问题！

@Controller
@RequestMapping("/demo")
public class HelloController  {
    @RequestMapping("/hello.do")
    public ModelAndView handleRequest(HttpServletRequest arg0,
            HttpServletResponse arg1) throws Exception {
          System.out.println("Hello, Controller.");
            return new ModelAndView("jsp/hello");
    }

}

 @Controller
@RequestMapping("/demo/hello.do")
public class HelloController  {
    public ModelAndView handleRequest(HttpServletRequest arg0,
            HttpServletResponse arg1) throws Exception {
          System.out.println("Hello, Controller.");
            return new ModelAndView("jsp/hello");
    }

}

有区别吗？为什么第二种写法会报错?