Spring MVC - Dropdown 下拉示例

以下示例描述了如何使用 Spring Web MVC 框架在表单中使用 Dropdown。首先，让我们有一个可以工作的 Eclipse IDE，并按照以下步骤使用 Spring Web 框架开发基于动态表单的 Web 应用程序。

步骤	说明
1	在包 com.tutorialspoint 下创建一个名称为 HelloWeb 的项目，如 Spring MVC - Hello World 一章中所述。
2	在 com.tutorialspoint 包下创建 Java 类 User、UserController。
3	在jsp子文件夹下创建视图文件user.jsp、users.jsp。
4	最后一步是创建源文件和配置文件的内容并导出应用程序，如下所述。

User.java

实例


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;
   
   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;
   }
}

UserController.java

实例


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());     
      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;
   }
}

这里，对于第一个服务方法user()，我们在ModelAndView对象中传入了一个空白的User对象，名称为 "command"，因为spring框架需要一个名称为 "command" 的对象，如果您在 JSP 文件中使用 <form:form> 标签。因此，当调用 user() 方法时，它会返回 user.jsp 视图。

第二个服务方法 addUser() 将针对 HelloWeb/addUser URL 上的 POST 方法调用。您将根据提交的信息准备模型对象。最后，“users”视图将从服务方法返回，这将导致呈现 users.jsp。

user.jsp

实例


<%@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 colspan = "2">
                  <input type = "submit" value = "Submit"/>
               </td>
            </tr>
         </table>  
      </form:form>
   </body>
</html>

在这里，我们使用 <form:select /> , <form:option /> 和 <form:options /> 标签来呈现 HTML 选择。例如 −

实例


<form:select path = "country">
   <form:option value = "NONE" label = "Select"/>
   <form:options items = "${countryList}" />
</form:select>

它将呈现以下 HTML 内容。

实例


<select id = "country" name = "country">
   <option value = "NONE">Select</option>
   <option value = "US">United States</option>
   <option value = "CH">China</option>
   <option value = "MY">Malaysia</option>
   <option value = "SG">Singapore</option>
</select>

users.jsp

实例


<%@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>   	  
      </table>  
   </body>
</html>

完成创建源文件和配置文件后，导出您的应用程序。右键单击您的应用程序，使用 Export → WAR File 选项并将 HelloWeb.war 文件保存在 Tomcat 的 webapps 文件夹中。

现在，启动 Tomcat 服务器并确保您能够使用标准浏览器从 webapps 文件夹访问其他网页。尝试以下 URL - http://localhost:8080/HelloWeb/user，如果 Spring Web 应用程序一切正常，我们将看到以下屏幕。

提交所需信息后，单击提交按钮提交表单。如果您的 Spring Web 应用程序一切正常，您应该会看到以下屏幕。

Spring MVC 教程

Spring MVC 表单处理

Spring MVC 表单标签库

Spring MVC 处理程序映射

Spring MVC 控制器

Spring MVC 视图解析器

Spring MVC 集成

Spring MVC 其他

Spring MVC - Dropdown 下拉示例

User.java

实例

UserController.java

实例

user.jsp

实例

实例

实例

users.jsp

实例

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