Spring MVC教程

Spring MVC列表多选框

以下示例显示如何在使用Spring Web MVC框架的表单中使用列表框(Listbox)。首先使用Eclipse IDE来创建一个WEB工程，实现一个让用户可选择自己所善长的技术(多选)的功能。并按照以下步骤使用Spring Web Framework开发基于动态表单的Web应用程序：

创建一个名称为 Listbox 的动态WEB项目。
在 com.zyiz.springmvc 包下创建两个Java类User，UserController。
在jsp子文件夹下创建两个视图文件：user.jsp，userlist.jsp。
最后一步是创建所有源和配置文件的内容并运行应用程序，详细如下所述。

完整的项目文件目录结构如下所示 -

User.java 的代码如下所示 -

package com.zyiz.springmvc;
public class User {

       private String username;
       private String password;
       private String address;
       private boolean receivePaper;
       private String [] favoriteFrameworks;   
       private String gender;
       private String favoriteNumber;
       private String country;
       private String [] skills;

       public String getUsername() {
          return username;
       }
       public void setUsername(String username) {
          this.username = username;
       }

       public String getPassword() {
          return password;
       }
       public void setPassword(String password) {
          this.password = password;
       }
       public String getAddress() {
          return address;
       }
       public void setAddress(String address) {
          this.address = address;
       }
       public boolean isReceivePaper() {
          return receivePaper;
       }
       public void setReceivePaper(boolean receivePaper) {
          this.receivePaper = receivePaper;
       }
       public String[] getFavoriteFrameworks() {
          return favoriteFrameworks;
       }
       public void setFavoriteFrameworks(String[] favoriteFrameworks) {
          this.favoriteFrameworks = favoriteFrameworks;
       }
       public String getGender() {
          return gender;
       }
       public void setGender(String gender) {
          this.gender = gender;
       }
       public String getFavoriteNumber() {
          return favoriteNumber;
       }
       public void setFavoriteNumber(String favoriteNumber) {
          this.favoriteNumber = favoriteNumber;
       }
       public String getCountry() {
          return country;
       }
       public void setCountry(String country) {
          this.country = country;
       }
       public String[] getSkills() {
          return skills;
       }
       public void setSkills(String[] skills) {
          this.skills = skills;
       }
    }

UserController.java 的代码如下所示 -

package com.zyiz.springmvc;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.springframework.stereotype.Controller;
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 org.springframework.ui.ModelMap;

@Controller
public class UserController {

   @RequestMapping(value = "/user", method = RequestMethod.GET)
   public ModelAndView user() {
      User user = new User();      
      user.setFavoriteFrameworks((new String []{"Spring MVC","Struts 2"}));
      user.setGender("M");
      ModelAndView modelAndView = new ModelAndView("user", "command", user);
      return modelAndView;
   }

   @RequestMapping(value = "/addUser", method = RequestMethod.POST)
   public String addUser(@ModelAttribute("SpringWeb")User user, 
      ModelMap model) {
      model.addAttribute("username", user.getUsername());
      model.addAttribute("password", user.getPassword());
      model.addAttribute("address", user.getAddress());
      model.addAttribute("receivePaper", user.isReceivePaper());
      model.addAttribute("favoriteFrameworks", user.getFavoriteFrameworks());
      model.addAttribute("gender", user.getGender());
      model.addAttribute("favoriteNumber", user.getFavoriteNumber());
      model.addAttribute("country", user.getCountry());
      model.addAttribute("skills", user.getSkills());
      return "userlist";
   }

   @ModelAttribute("webFrameworkList")
   public List<String> getWebFrameworkList()
   {
      List<String> webFrameworkList = new ArrayList<String>();
      webFrameworkList.add("Spring MVC");
      webFrameworkList.add("Struts 1");
      webFrameworkList.add("Struts 2");
      webFrameworkList.add("Apache Hadoop");
      return webFrameworkList;
   }

   @ModelAttribute("numbersList")
   public List<String> getNumbersList()
   {
      List<String> numbersList = new ArrayList<String>();
      numbersList.add("1");
      numbersList.add("2");
      numbersList.add("3");
      numbersList.add("4");
      return numbersList;
   }

   @ModelAttribute("countryList")
   public Map<String, String> getCountryList()
   {
      Map<String, String> countryList = new HashMap<String, String>();
      countryList.put("US", "United States");
      countryList.put("CH", "China");
      countryList.put("SG", "Singapore");
      countryList.put("MY", "Malaysia");
      return countryList;
   }

   @ModelAttribute("skillsList")
   public Map<String, String> getSkillsList()
   {
      Map<String, String> skillList = new HashMap<String, String>();
      skillList.put("Hibernate", "Hibernate");
      skillList.put("Spring", "Spring");
      skillList.put("Apache Hadoop", "Apache Hadoop");
      skillList.put("Struts", "Struts");
      return skillList;
   }
}

这里的第一个服务方法user()，我们已经在ModelAndView对象中传递了一个名称为“command”的空User对象，因为如果在JSP文件中使用<form:form>标签，spring框架需要一个名称为“command”的对象。所以当调用user()方法时，它返回user.jsp视图。

第二个服务方法addUser()将根据URL => Listbox/addUser 上的POST方法请求时调用。根据提交的信息准备模型对象。最后从服务方法返回“userlist”视图，这将呈现userlist.jsp视图。

user.jsp 的代码如下所示 -

<%@ page contentType="text/html; charset=UTF-8"%>

<%@taglib uri="http://www.springframework.org/tags/form" prefix="form"%>
<html>
<head>
<title>Spring MVC表单处理(列表框)</title>
</head>
<body>

    <h2>用户信息</h2>
    <form:form method="POST" action="/Listbox/addUser">
        <table>
            <tr>
                <td><form:label path="username">用户名：</form:label></td>
                <td><form:input path="username" /></td>
            </tr>
            <tr>
                <td><form:label path="password">密码：</form:label></td>
                <td><form:password path="password" /></td>
            </tr>
            <tr>
                <td><form:label path="address">地址：</form:label></td>
                <td><form:textarea path="address" rows="5" cols="30" /></td>
            </tr>
            <tr>
                <td><form:label path="receivePaper">是否订阅：</form:label></td>
                <td><form:checkbox path="receivePaper" /></td>
            </tr>
            <tr>
                <td><form:label path="favoriteFrameworks">喜欢的框架/技术：</form:label></td>
                <td><form:checkboxes items="${webFrameworkList}"
                        path="favoriteFrameworks" /></td>
            </tr>
            <tr>
                <td><form:label path="gender">性别：</form:label></td>
                <td><form:radiobutton path="gender" value="M" label="男" /> <form:radiobutton
                        path="gender" value="F" label="女" /></td>
            </tr>
            <tr>
                <td><form:label path="favoriteNumber">喜欢的数字：</form:label></td>
                <td><form:radiobuttons path="favoriteNumber"
                        items="${numbersList}" /></td>
            </tr>
            <tr>
                <td><form:label path="country">所在国家：</form:label></td>
                <td><form:select path="country">
                        <form:option value="NONE" label="请选择..." />
                        <form:options items="${countryList}" />
                    </form:select></td>
            </tr>
            <tr>
            <td><form:label path="skills">技术：</form:label></td>
            <td><form:select path="skills" items="${skillsList}"
                    multiple="true" /></td>
        </tr>
            <tr>
                <td colspan="2"><input type="submit" value="提交" /></td>
            </tr>
        </table>
    </form:form>
</body>
</html>

这里使用<form:select /> 及其属性 multiple=true标签来呈现HTML列表多选框。例如 -

<form:select path="skills" items="${skillsList}" multiple="true" />

它将呈现以下HTML内容。

<select id="skills" name="skills" multiple="multiple">
   <option value="Struts">Struts</option>
   <option value="Hibernate">Hibernate</option>
   <option value="Apache Wicket">Apache Hadoop</option>
   <option value="Spring">Spring</option>
</select>
<input type="hidden" name="_skills" value="1"/>

userlist.jsp 的代码如下所示 -

<%@ page contentType="text/html; charset=UTF-8"%>
<%@taglib uri="http://www.springframework.org/tags/form" prefix="form"%>
<html>
<head>
<title>Spring MVC表单处理(列表框)</title>
</head>
<body>

    <h2>提交用户信息 -</h2>
    <table>
        <tr>
            <td>用户名：</td>
            <td>${username}</td>
        </tr>
        <tr>
            <td>密码：</td>
            <td>${password}</td>
        </tr>
        <tr>
            <td>地址：</td>
            <td>${address}</td>
        </tr>
        <tr>
            <td>是否订阅：</td>
            <td>${receivePaper}</td>
        </tr>
        <tr>
            <td>喜欢的技术/框架：</td>
            <td>
                <%
                    String[] favoriteFrameworks = (String[]) request.getAttribute("favoriteFrameworks");
                    for (String framework : favoriteFrameworks) {
                        out.println(framework);
                    }
                %>
            </td>
        </tr>
        <tr>
            <td>性别：</td>
            <td>${(gender=="M"? "男" : "女")}</td>
        </tr>
        <tr>
            <td>喜欢的数字：</td>
            <td>${favoriteNumber}</td>
        </tr>
        <tr>
            <td>国家：</td>
            <td>${country}</td>
        </tr>
        <tr>
                <td>技术：</td>
                <td>
                    <%
                        String[] skills = (String[]) request.getAttribute("skills");
                            for (String skill : skills) {
                                out.println(skill);
                            }
                    %>
                </td>
            </tr>

    </table>
</body>
</html>

完成创建源和配置文件后，发布应用程序到Tomcat服务器。

现在启动Tomcat服务器，现在尝试访问URL => http://localhost:8080/Listbox/user ，如果Spring Web应用程序没有问题，应该看到以下结果：

提交所需信息后，点击提交按钮提交表单。如果Spring Web应用程序没有问题，应该看到以下结果：

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