Spring jsp 验证 form:errors标签

1 在model层添加验证规则

    @NotNull
    @Size(min=2,max =30,message="姓名在2-30个字符之间")
    private String username;

2. 在model层添加验证规则

    @PostMapping("/save")
   public String save(@Valid User user, BindingResult result, RedirectAttributes redirectAttributes,Model model) {

       if(result.hasErrors()){
           user.setXb("女");
           model.addAttribute("user",user);
           model.addAttribute("jinengItme",jineng());
           model.addAttribute("guxiang",getGuxiang());
           return "hello";
       }

@Valid导入验证规则,BindingResult导入验证信息

result.hasErrors()遍历错误信息并输出
3.在视图层使用form:errors标签显示错误

<form:errors path="username" />