Spring MVC dropdown box example

In Spring MVC, form tags – <form:select />, <form:option /> or <form:options />, are used to render HTML dropdown box. See following examples :

//SimpleFormController
protected Map referenceData(HttpServletRequest request) throws Exception {
    Map referenceData = new HashMap();
    Map<String,String> country = new LinkedHashMap<String,String>();
    country.put("US", "United Stated");
    country.put("CHINA", "China");
    country.put("SG", "Singapore");
    country.put("MY", "Malaysia");
    referenceData.put("countryList", country);
}

1. <form:select />

Generate a dropbox box with ${countryList}.

<form:select path="country" items="${countryList}" />

HTML code

<select id="country" name="country">
   <option value="US">United Stated</option>
   <option value="CHINA">China</option>
   <option value="SG">Singapore</option>
   <option value="MY">Malaysia</option>
</select> 

2. <form:options />

The <form:options /> have to enclosed with the select tag.

<form:select path="country">
    <form:options items="${countryList}" />
</form:select>

HTML code

<select id="country" name="country">
   <option value="US">United Stated</option>
   <option value="CHINA">China</option>
   <option value="SG">Singapore</option>
   <option value="MY">Malaysia</option>
</select> 

3. <form:option />

The <form:option /> have to enclosed with the select tag as well, and render a single select option, see the following combination.

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

HTML code

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

4. List box

To render a list box, just add the “multiple=true” attribute in the select tag.

<form:select path="country" items="${countryList}" multiple="true" />

HTML code, with a hidden value to handle the country selections.

<select id="country" name="country" multiple="multiple"> 
    <option value="US">United Stated</option>
    <option value="CHINA">China</option>
    <option value="SG">Singapore</option>
    <option value="MY">Malaysia</option> 
</select>
<input type="hidden" name="_country" value="1"/> 

Select a dropdown box value
For dropdown box, list box or “select” options, as long as the “path” or “property” is equal to the “select option key value“, the options will be selected automatically.

Full dropdown box example

Let’s go thought a complete Spring MVC dropdown box example :

1. Model

A customer model class to store the dropdown box value.

File : Customer.java

package com.mkyong.customer.model;

public class Customer{

    String country;
    String javaSkills;

    public String getCountry() {
        return country;
    }
    public void setCountry(String country) {
        this.country = country;
    }
    public String getJavaSkills() {
        return javaSkills;
    }
    public void setJavaSkills(String javaSkills) {
        this.javaSkills = javaSkills;
    }   
}

2. Controller

A SimpleFormController to handle the form dropdown box value. Make the java skills’s “Spring” as the default dropdown box selected value.

File : DropDownBoxController.java

package com.mkyong.customer.controller;

import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.validation.BindException;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.SimpleFormController;
import com.mkyong.customer.model.Customer;

public class DropDownBoxController extends SimpleFormController{

    public DropDownBoxController(){
        setCommandClass(Customer.class);
        setCommandName("customerForm");
    }

    @Override
    protected Object formBackingObject(HttpServletRequest request)
        throws Exception {

        Customer cust = new Customer();

        //make "Spring" as the default java skills selection
        cust.setJavaSkills("Spring");

        return cust;

    }

    @Override
    protected ModelAndView onSubmit(HttpServletRequest request,
        HttpServletResponse response, Object command, BindException errors)
        throws Exception {

        Customer customer = (Customer)command;
        return new ModelAndView("CustomerSuccess","customer",customer);

    }

    protected Map referenceData(HttpServletRequest request) throws Exception {

        Map referenceData = new HashMap();

        Map<String,String> country = new LinkedHashMap<String,String>();
        country.put("US", "United Stated");
        country.put("CHINA", "China");
        country.put("SG", "Singapore");
        country.put("MY", "Malaysia");
        referenceData.put("countryList", country);

        Map<String,String> javaSkill = new LinkedHashMap<String,String>();
        javaSkill.put("Hibernate", "Hibernate");
        javaSkill.put("Spring", "Spring");
        javaSkill.put("Apache Wicket", "Apache Wicket");
        javaSkill.put("Struts", "Struts");
        referenceData.put("javaSkillsList", javaSkill);

        return referenceData;
    }
}

3. Validator

A simple form validator to make sure the “country” and “javaSkills” dropdown box is selected.

File : DropDownBoxValidator.java

package com.mkyong.customer.validator;

import org.springframework.validation.Errors;
import org.springframework.validation.ValidationUtils;
import org.springframework.validation.Validator;

import com.mkyong.customer.model.Customer;

public class DropDownBoxValidator implements Validator{

    @Override
    public boolean supports(Class clazz) {
       //just validate the Customer instances
       return Customer.class.isAssignableFrom(clazz);
    }

    @Override
    public void validate(Object target, Errors errors) {

       Customer cust = (Customer)target;

       ValidationUtils.rejectIfEmptyOrWhitespace(errors, "javaSkills", "required.javaSkills");

       if("NONE".equals(cust.getCountry())){
        errors.rejectValue("country", "required.country");
       }
    }
}

File : message.properties

required.country = Please select a country!
required.javaSkills = Please select a java Skill!   

4. View

A JSP page to show the use of Spring’s form tag <form:select />, <form:option /> and <form:options />.

File : CustomerForm.jsp

<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>
<html>
<head>
<style>
.error {
    color: #ff0000;
}

.errorblock {
    color: #000;
    background-color: #ffEEEE;
    border: 3px solid #ff0000;
    padding: 8px;
    margin: 16px;
}
</style>
</head>

<body>
    <h2>Spring's form select, option, options example</h2>

    <form:form method="POST" commandName="customerForm">
        <form:errors path="*" cssClass="errorblock" element="div" />
        <table>

            <tr>
                <td>Country :</td>
                <td><form:select path="country">
                      <form:option value="NONE" label="--- Select ---" />
                      <form:options items="${countryList}" />
                       </form:select>
                                </td>
                <td><form:errors path="country" cssClass="error" /></td>
            </tr>
            <tr>
                <td>Java Skills :</td>
                <td><form:select path="javaSkills" items="${javaSkillsList}"
                    multiple="true" /></td>
                <td><form:errors path="javaSkills" cssClass="error" /></td>
            </tr>

            <tr>
                <td colspan="3"><input type="submit" /></td>
            </tr>
        </table>
    </form:form>

</body>
</html>

Use JSTL to display submitted value.

File : CustomerSuccess.jsp

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>

<html>
<body>
    <h2>Spring's form select, option, options example</h2>

    Country : ${customer.country}
    <br /> Java Skills : ${customer.javaSkills}
    <br />

</body>
</html>

5. Spring Bean Configuration

Link it all ~

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans 
    http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">

  <bean
  class="org.springframework.web.servlet.mvc.support.ControllerClassNameHandlerMapping" />

    <bean class="com.mkyong.customer.controller.DropDownBoxController">
        <property name="formView" value="CustomerForm" />
        <property name="successView" value="CustomerSuccess" />

        <!-- Map a validator -->
        <property name="validator">
            <bean class="com.mkyong.customer.validator.DropDownBoxValidator" />
        </property>
    </bean>

    <!-- Register the Customer.properties -->
    <bean id="messageSource"
        class="org.springframework.context.support.ResourceBundleMessageSource">
        <property name="basename" value="message" />
    </bean>

    <bean id="viewResolver"
        class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix">
            <value>/WEB-INF/pages/</value>
        </property>
        <property name="suffix">
            <value>.jsp</value>
        </property>
    </bean>
</beans>

6. Demo

Access the page – http://localhost:8080/SpringMVCForm/dropdownbox.htm

If the user did not select any dropdown box value while submitting the form, display and highlight the error message.

If the form is submitted successfully, just display the submitted dropdown box values.