Controlloer
@Validations(

requiredStringValidators = {
                            @RequiredStringValidator(field = "name", message = "姓名不能为空!", trim = true),
                            @RequiredStringValidator(field = "email", message = "邮箱不能为空!", trim = true),
                            @RequiredStringValidator(field = "mobile", message = "手机不能为空!", trim = true),
                            @RequiredStringValidator(field = "username", message = "用户名不能为空!", trim = true),
                            @RequiredStringValidator(field = "userType", message = "用户类型不能为空!", trim = true) },

stringLengthValidators = { @StringLengthValidator(field = "username", message = "用户名只能在6-12位之间", minLength = "5", maxLength = "12") },

emailValidators = { @EmailValidator(field = "email", message = "邮箱格式不正确!") })
@RequestMapping(value = "/admin_save")
public String save(HttpServletRequest request, ModelMap model,
                   @RequestParam(value = "rePassword") String rePassword, Admin admin) {

    if (admin.getId() == null && StringUtils.isBlank(admin.getPassword())) {
        FormUtils.addFormError(request, "password", "密码不能为空!");
    } else if (StringUtils.isNotBlank(admin.getPassword())
               && !StringUtils.equals(admin.getPassword(), rePassword)) {
        FormUtils.addFormError(request, "rePassword", "两次密码不一致!");
    }

    if (FormUtils.hasErrors(request)) {
        return "admin/user_input";
    }
    userService.save(admin);

    return "redirect:admin_list.jhtml";
}

然后通过FormUtils.getFormErrors来显示错误