Spring 3 MVC:显示带有自定义验证程序的验证消息 [英] Spring 3 MVC: Show validation message with custom validator

问题描述

我需要帮助.我是jsp，MVC的初学者.我想在Spring 3 MVC中使用自定义验证器来验证表单输入.

I need help. I am beginner in jsp, MVC. I want to validate form input with custom validator in Spring 3 MVC.

我的验证器类

   package validators;

import models.UserModel;

import org.springframework.stereotype.Component;
import org.springframework.validation.Errors;
import org.springframework.validation.ValidationUtils;
import org.springframework.validation.Validator;
@Component
public class UserValidator implements Validator {

   @Override
   public boolean supports(Class clazz) {
      return UserModel.class.isAssignableFrom(clazz);
   }

   @Override
   public void validate(Object target, Errors errors) {
      ValidationUtils.rejectIfEmptyOrWhitespace(errors, "firstname", "Enter firstname.");
      ValidationUtils.rejectIfEmptyOrWhitespace(errors, "surname", "Enter surname.");
      ValidationUtils.rejectIfEmptyOrWhitespace(errors, "login", "Enter login.");

   }

}

控制器类

package controllers;

import java.util.ArrayList;
import models.UserModel;
import org.springframework.stereotype.Controller;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.servlet.ModelAndView;
import validators.UserValidator;
import database.UserDB;


@Controller
public class UserController {

@RequestMapping(value="pouzivatel/new", method=RequestMethod.POST)
   public ModelAndView newUser(@ModelAttribute UserModel user, BindingResult result){
      UserValidator validator = new UserValidator();
      validator.validate(user, result);
      if(result.hasErrors()){
         return new ModelAndView("/user/new","command",user);

      }
      ...
}

用户模型

package models;

public class UserModel  {
   private String firstname="";
   private String surname="";

   public String getFirstname() {
      return firstname;
   }
   public String getSurname() {
      return surname;
   }

   public void setFirstname(String firstname) {
      this.firstname = firstname;
   }
   public void setSurname(String surname) {
      this.surname = surname;
   }

}

位于/web-inf/user目录中的JSP veiw new.jsp(仅用于表单)

JSP veiw new.jsp which is in directory /web-inf/user (it just only form)

<form:form method="post" action="new.html">
            <fieldset>
               <table>
                  <tr>
                     <td>
                        <form:label path="firstname">FirstName</form:label>
                     </td>
                     <td>
                        <form:input path="firstname" />
                        <form:errors path="firstname" />
                     </td>
                  </tr>
                  <tr>
                     <td>
                        <form:label path="surname">Surname</form:label>
                     </td>
                     <td>
                        <form:input path="surname" />
                        <form:errors path="surname" />
                     </td>
                  </tr>
               </table>
            </fieldset>
            <div>
               <button type="submit" id="btOk">Ok</button>
            </div>
</form:form>

调度程序servlet.xml

dispatcher servlet.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xmlns:p="http://www.springframework.org/schema/p"
   xmlns:context="http://www.springframework.org/schema/context"
   xsi:schemaLocation="http://www.springframework.org/schema/beans
      http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
      http://www.springframework.org/schema/context
      http://www.springframework.org/schema/context/spring-context-3.0.xsd">

   <context:component-scan base-package="controllers" />
    <context:component-scan base-package="validators" />

   <bean id="viewResolver" class="org.springframework.web.servlet.view.UrlBasedViewResolver">
      <property name="viewClass" value="org.springframework.web.servlet.view.JstlView" />
      <property name="prefix" value="/WEB-INF/jsp/" />
      <property name="suffix" value=".jsp" />
   </bean>

</beans>

问题是视图中的显示验证消息.验证成功，并且变量resut(BindingResult)中存在错误.控制器返回遵循部分代码

Problem is a display validation message in view. Validation is successful and in variable resut (BindingResult) are errors. Controller return follow part of code

if(result.hasErrors()){
         return new ModelAndView("/user/new","command",user);

另一种方法是使用注释验证(我提供自定义验证器)，但是为什么当输入字段为空时，我在视图上看不到验证消息.

Another way is use Annotation validation (I preffer custom validator), but why i can not see validation messages on view, when input fields are empty.

您能举个例子吗?

感谢您的答复.

推荐答案

之所以发生这种情况，是因为视图和控制器中的默认模型属性名称不匹配:

This happens because of mismatch between default model attribute names in view and controller:

• 编写不带modelAttribute(或commandName)属性的<form:form>时，它将使用默认的模型属性名称command.
• 当您在控制器中编写@ModelAttribute UserModel user时，它假定此属性的名称为大写的类名称，即userModel.

• When you write <form:form> without modelAttribute (or commandName) attribute, it uses default model attribute name command.
• When you write @ModelAttribute UserModel user in your controller, it assumes that the name of this attribute is a decapitalized class name, i.e. userModel.

也就是说，验证器产生的错误消息绑定到名为userModel的模型属性，而视图试图显示模型属性command的错误.

That is, error messages produced by validator are bound to model attribute named userModel, while your view tries to show errors for model attribute command.

您需要在视图(<form:form modelAttribute = "userModel" ...>)或控制器(@ModelAttribute("command"))中显式设置模型属性名称.

You need to set a model attribute name explicitly, either in the view (<form:form modelAttribute = "userModel" ...>) or in the controller (@ModelAttribute("command")).

这篇关于Spring 3 MVC:显示带有自定义验证程序的验证消息的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！