@ModelAttribute Spring MVC 多选未设置 ArrayList答案

【问题标题】：@ModelAttribute Spring MVC multiple select not setting the ArrayList@ModelAttribute Spring MVC 多选未设置 ArrayList
【发布时间】：2015-12-24 16:11:28
【问题描述】：

我正在从基本教程中尝试 Spring MVC。我遇到了一个问题，我试图将数据从 HTML 表单绑定到模型对象。像

这样的字段很少

private String studentName;
private String studentHobby;
private Long studentMobile;
private Date studentDOB;
private ArrayList<String> studentSkills;

所有字段都设置正确，我可以在另一个 jsp 上正确显示它们，除了技能字段是 ArrayList。

Name: ${student.studentName}<br>
Hobby: ${student.studentHobby}<br>
Mobile: ${student.studentMobile}<br>
DOB: ${student.studentDOB}<br>
Skills: ${student.studentSkills}<br>

我的代码如下：

package com.springMVC.controller;

import java.util.ArrayList;
import java.util.List;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
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.bind.annotation.RequestParam;
import org.springframework.web.servlet.ModelAndView;

import com.springMVC.model.Student;

@Controller
public class StudentAdmissionController 
{

@ModelAttribute
public void addCommonObjects(Model model)
{
    model.addAttribute("headerMsg","welcome to spring learning!");
}

@RequestMapping(value="/admissionForm",method=RequestMethod.GET)
public ModelAndView getAdmissionForm() 
{
    System.out.println("inside getAdmission");
    ModelAndView model = new ModelAndView("AdmissionForm");
    return model;
}




@RequestMapping(value="submitAdmissionForm",method=RequestMethod.POST)
public ModelAndView submitAdmissionForm(@ModelAttribute("student") Student student,BindingResult result)
{
    System.out.println("inside submitAdmissionForm name: "+student.getStudentName()+" hobby: "+student.getStudentHobby());

    ModelAndView model = new ModelAndView("AdmissionSuccess");

    return model;
}

}

AdmissionForm.jsp：

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%@ page isELIgnored="false" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<b>${headerMsg }</b>
    <form action="/SpringMVCDemo/submitAdmissionForm" method="post">
        studentName: <input type="text" name="studentName"><br>
        studentHobby: <input type="text" name="studentHobby"><br>
        studentMobile: <input type="text" name="studentMobile"><br>
        studentDOB: <input type="text" name="studentDOB"><br>
        StudenSkills: <select name="studentSkills" multiple>
                        <option value="java">java</option>
                        <option value="Java">java2</option>
                        <option value="JAVA">java3</option>
                      </select>
        <input type="submit">
    </form>
</body>
</html>

AdmissionSuccess.jsp：

 <%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
    <%@ page isELIgnored="false" %>

     <%@ taglib uri='http://java.sun.com/jsp/jstl/core' prefix='c'%>
     <%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<h1>${headerMsg }</h1>
<h1>Congratulations!</h1>
<h2>Name: ${student.studentName}</h2><br>
<h2>Hobby: ${student.studentHobby}</h2><br>
<h2>Mobile: ${student.studentMobile}</h2><br>
<h2>${student.studentDOB}</h2><br>
<h2>Skills: ${student.studentSkills}</h2><br>
</body>
</html>

首先这些链接带来http://localhost:8080/SpringMVCDemo/admissionForm.html的形式

并在提交相同的捕获数据后显示在另一个jsp中。

【问题讨论】：

贴出Student的代码。将 studentiSkills 的类型更改为List<String>
@JBNizet 你把我带到了那里！它是 ArrayList。我不知道为什么我会这样写。非常感谢。请添加您的评论作为解决方案。非常感谢...

标签： java spring jsp spring-mvc modelattribute

【解决方案1】：

studentSkills 属性必须是 List<String> 类型，而不是 ArrayList<String>。

【讨论】：

【解决方案2】：

 <%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %> 
<%@ taglib uri='http://java.sun.com/jsp/jstl/core' prefix='c'%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<h1>${headerMsg }</h1>
<h1>Congratulations!</h1>
<h2>Name: ${student.studentName}</h2><br>
<h2>Hobby: ${student.studentHobby}</h2><br>
<h2>Mobile: ${student.studentMobile}</h2><br>
<h2>Date of Birth: ${student.studentDOB}</h2><br>
<h2>Skills: ${student.studentSkills}</h2><br>
</body>
</html>

【讨论】：