Spring MVC - 複選框示例

以下示例解釋瞭如何使用 Spring Web MVC 框架在表單中使用多個複選框。首先，我們需要一個可用的 Eclipse IDE，並按照以下步驟使用 Spring Web 框架開發基於動態表單的 Web 應用程式。

步驟	描述
1	建立一個名為 HelloWeb 的專案，其包名為 com.tutorialspoint，如 Spring MVC - Hello World 章節中所述。
2	在 com.tutorialspoint 包下建立 Java 類 User 和 UserController。
3	在 jsp 子資料夾下建立檢視檔案 user.jsp 和 users.jsp。
4	最後一步是建立原始檔和配置檔案的內容，並匯出應用程式，如下所述。

User.java

package com.tutorialspoint;

public class User {
	
   private String username;
   private String password;
   private String address;
   private boolean receivePaper;
   private String [] favoriteFrameworks;   

   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;
   }
}

UserController.java

package com.tutorialspoint;

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

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"}));
	  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());
      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;
   }
}

這裡，對於第一個服務方法 **user()**，我們在 ModelAndView 物件中傳遞了一個空的 **User** 物件，其名稱為“command”，因為如果您在 JSP 檔案中使用 <form:form> 標籤，Spring 框架期望有一個名為“command”的物件。因此，當呼叫 **user()** 方法時，它將返回 **user.jsp** 檢視。

第二個服務方法 **addUser()** 將針對 **HelloWeb/addUser** URL 上的 POST 方法呼叫。您將根據提交的資訊準備模型物件。最後，服務方法將返回“users”檢視，這將導致渲染 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 colspan = "2">
                  <input type = "submit" value = "Submit"/>
               </td>
            </tr>
         </table>  
      </form:form>
   </body>
</html>

在這裡，我們使用 **<form:checkboxes />** 標籤來渲染 HTML 複選框。

<form:checkboxes items = "${webFrameworkList}" path = "favoriteFrameworks" />

它將渲染以下 HTML 內容。

<span>
   <input id = "favoriteFrameworks1" name = "favoriteFrameworks" type = "checkbox" value = "Spring MVC" checked = "checked"/>
   <label for = "favoriteFrameworks1">Spring MVC</label>
</span>
<span>
   <input id = "favoriteFrameworks2" name = "favoriteFrameworks" type = "checkbox" value = "Struts 1"/>
   <label for = "favoriteFrameworks2">Struts 1</label>
</span>
<span>
   <input id = "favoriteFrameworks3" name = "favoriteFrameworks" type = "checkbox" value = "Struts 2" checked = "checked"/>
   <label for = "favoriteFrameworks3">Struts 2</label>
</span>
<span>
   <input id = "favoriteFrameworks4" name = "favoriteFrameworks" type = "checkbox" value = "Apache Wicket"/>
   <label for = "favoriteFrameworks4">Apache Wicket</label>
</span>
<input type = "hidden" name = "_favoriteFrameworks" value = "on"/>

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

建立完原始檔和配置檔案後，匯出您的應用程式。右鍵單擊您的應用程式，使用 **匯出 → WAR 檔案** 選項，並將您的 **HelloWeb.war** 檔案儲存在 Tomcat 的 webapps 資料夾中。

現在，啟動 Tomcat 伺服器，並確保您可以使用標準瀏覽器訪問 webapps 資料夾中的其他網頁。嘗試使用 URL **https://:8080/HelloWeb/user**，如果 Spring Web 應用程式一切正常，我們將看到以下螢幕。

提交所需資訊後，單擊提交按鈕提交表單。如果您的 Spring Web 應用程式一切正常，我們將看到以下螢幕。

列印頁面