springmv 后台传给前台页面数据的4种方法

<p style="color:red;font-size:20px;">
<c:if test="${not empty errorStr}">
${errorStr}
</c:if>
</p>

@RequestMapping(value="/login",method = RequestMethod.POST)
public String login(User user,Model model) {
String info = loginUser(user);
if(!"SUCC".equals(info)){
model.addAttribute("errorStr", "用户名或密码错误");
return "login";
}else
return "index";
}

@RequestMapping(value="/login",method = RequestMethod.POST)
public String login(User user,HttpServletRequest request) {
String info = loginUser(user);
if(!"SUCC".equals(info)){
request.setAttribute("errorStr", "用户名或密码错误");
return "login";
}else
return "index";
}

@RequestMapping(value="/login",method = RequestMethod.POST)
public String login(User user,Map map) {
String info = loginUser(user);
if(!"SUCC".equals(info)){
List<String> list = new ArrayList<String>();
list.add("用户名或密码错误");
map.put("errorStr", list);
return "login";
}else
return "index";
}

@RequestMapping(value="/login",method= RequestMethod.POST)
public ModelAndView login(User user){
ModelAndView mav= new ModelAndView();
String info = loginUser(user);
if(!"SUCC".equals(info){
mav.setViewName("login");
mav.addObject("errorStr","用户名或密码错误");
}else
mav.setViewName("index");
return mav;
}