Springmvc 简明教程

Spring MVC - Listbox Example

以下示例展示了如何在表单中使用Spring Web MVC框架中的列表框。首先，让我们使用Eclipse IDE并按照后续步骤使用Spring Web框架开发一个基于动态表单的Web应用程序。

The following example shows how to use Listbox in forms using the Spring Web MVC framework. To begin with, let us have a working Eclipse IDE in place and follow the subsequent steps to develop a Dynamic Form based Web Application using the Spring Web Framework.

Step

Description

1

Create a project with a name HelloWeb under a package com.tutorialspoint as explained in the Spring MVC - Hello World chapter.

2

Create Java classes User, UserController under the com.tutorialspointpackage.

3

Create view files user.jsp, users.jsp under the jsp sub-folder.

4

The final step is to create the content of the source and configuration files and export the application as explained below.

User.java

package com.tutorialspoint;

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

package com.tutorialspoint;

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 "users";
   }

   @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 Wicket");
      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 Wicket", "Apache Wicket");
      skillList.put("Struts", "Struts");
      return skillList;
   }
}

在这里，对于第一个服务方法 user() ，我们在 ModelAndView 对象中传递了一个空白 User 对象，名称为“command”，这是因为如果你在 JSP 文件中使用 <form:form> 标记，则 Spring 框架需要一个名为“command”的对象。因此，当调用 user() 方法时，它将返回 user.jsp 视图。

Here, for the first service method user(), we have passed a blank User object in the ModelAndView object with name "command", because the spring framework expects an object with name "command", if you are using <form:form> tags in your JSP file. So, when the user() method is called, it returns the user.jsp view.

第二个服务方法 addUser() 将针对 HelloWeb/addUser URL 上的 POST 方法进行调用。你将根据提交的信息准备你的模型对象。最后，将在服务方法中返回“users”视图，这会导致呈现 users.jsp。

The second service method addUser() will be called against a POST method on the HelloWeb/addUser URL. You will prepare your model object based on the submitted information. Finally, the "users" view will be returned from the service method, which will result in rendering the users.jsp.

user.jsp

<%@taglib uri = "http://www.springframework.org/tags/form" prefix = "form"%>
<html>
   <head>
      <title>Spring MVC Form Handling</title>
   </head>
   <body>

      <h2>User Information</h2>
      <form:form method = "POST" action = "/HelloWeb/addUser">
         <table>
            <tr>
               <td><form:label path = "username">User Name</form:label></td>
               <td><form:input path = "username" /></td>
            </tr>
            <tr>
               <td><form:label path = "password">Age</form:label></td>
               <td><form:password path = "password" /></td>
            </tr>
            <tr>
               <td><form:label path = "address">Address</form:label></td>
               <td><form:textarea path = "address" rows = "5" cols = "30" /></td>
            </tr>
            <tr>
               <td><form:label path = "receivePaper">Subscribe Newsletter</form:label></td>
               <td><form:checkbox path = "receivePaper" /></td>
            </tr>
            <tr>
               <td><form:label path = "favoriteFrameworks">Favorite Web Frameworks</form:label></td>
               <td><form:checkboxes items = "${webFrameworkList}" path = "favoriteFrameworks" /></td>
            </tr>
            <tr>
               <td><form:label path = "gender">Gender</form:label></td>
               <td>
                  <form:radiobutton path = "gender" value = "M" label = "Male" />
                  <form:radiobutton path = "gender" value = "F" label = "Female" />
               </td>
            </tr>
            <tr>
               <td><form:label path = "favoriteNumber">Favorite Number</form:label></td>
               <td>
                  <form:radiobuttons path = "favoriteNumber" items = "${numbersList}" />
               </td>
            </tr>
            <tr>
               <td><form:label path = "country">Country</form:label></td>
               <td>
                  <form:select path = "country">
                     <form:option value = "NONE" label = "Select"/>
                     <form:options items = "${countryList}" />
                  </form:select>
               </td>
            </tr>
            <tr>
               <td><form:label path = "skills">Skills</form:label></td>
               <td>
                  <form:select path = "skills" items = "${skillsList}"
                     multiple = "true" />
               </td>
            </tr>
            <tr>
               <td colspan = "2">
                  <input type = "submit" value = "Submit"/>
               </td>
            </tr>
         </table>
      </form:form>
   </body>
</html>

在这里，我们使用 <form:select /> 标记，其中具有属性 multiple=true 来绘制一个HTML列表框。例如 −

Here, we are using a <form:select /> tag , with the attribute multiple=true to render an HTML listbox. For example −

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

它会呈现以下 HTML 内容。

It will render following HTML content.

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

users.jsp

<%@taglib uri = "http://www.springframework.org/tags/form" prefix = "form"%>
<html>
   <head>
      <title>Spring MVC Form Handling</title>
   </head>
   <body>

      <h2>Submitted User Information</h2>
      <table>
         <tr>
            <td>Username</td>
            <td>${username}</td>
         </tr>
         <tr>
            <td>Password</td>
            <td>${password}</td>
         </tr>
         <tr>
            <td>Address</td>
            <td>${address}</td>
         </tr>
         <tr>
            <td>Subscribed to Newsletter</td>
            <td>${receivePaper}</td>
         </tr>
         <tr>
            <td>Favorite Web Frameworks</td>
            <td> <% String[] favoriteFrameworks = (String[])request.getAttribute("favoriteFrameworks");
               for(String framework: favoriteFrameworks) {
                  out.println(framework);
               }
            %></td>
         </tr>
         <tr>
            <td>Gender</td>
            <td>${(gender=="M"? "Male" : "Female")}</td>
         </tr>
         <tr>
            <td>Favourite Number</td>
            <td>${favoriteNumber}</td>
         </tr>
         <tr>
            <td>Country</td>
            <td>${country}</td>
         </tr>
         <tr>
            <td>Skills</td>
            <td> <% String[] skills = (String[])request.getAttribute("skills");
            for(String skill: skills) {
               out.println(skill);
            }
            %></td>
         </tr>
      </table>
   </body>
</html>

创建源文件和配置文件后，导出应用程序。右键单击应用程序，然后单击 Export → WAR File 选项，并通过 Tomcat 的 webapps 文件夹保存 HelloWeb.war 文件。

Once you are done with creating source and configuration files, export your application. Right click on your application, use Export → WAR File option and save the HelloWeb.war file in Tomcat’s webapps folder.

现在，启动Tomcat服务器，并确保您能通过标准浏览器访问webapps文件夹中的其它网页。尝试一个URL − http://localhost:8080/HelloWeb/user ，如果Spring Web应用程序正常，我们将看到以下屏幕。

Now, start the Tomcat server and make sure you are able to access other webpages from the webapps folder using a standard browser. Try a URL − http://localhost:8080/HelloWeb/user and we will see the following screen, if everything is fine with the Spring Web Application.

spring listbox

在提交所需的信息后，单击提交按钮以提交表单。如果 Spring Web 应用程序一切正常，你应该会看到以下屏幕。

After submitting the required information, click on the submit button to submit the form. You should see the following screen, if everything is fine with your Spring Web Application.

spring listbox result