Spring MVC form handling annotation example

REf:- http://www.mkyong.com/spring-mvc/spring-mvc-form-handling-annotation-example/

1. SimpleFormController vs @Controller

In XML-based Spring MVC web application, you create a form controller by extending the SimpleFormController class.

In annotation-based, you can use @Controller instead.

SimpleFormController

public class CustomerController extends SimpleFormController{
      //...
}

Annotation

@Controller
@RequestMapping("/customer.htm")
public class CustomerController{
      //...
}

2. formBackingObject() vs RequestMethod.GET
In SimpleFormController, you can initialize the command object for binding in the formBackingObject() method. In annotation-based, you can do the same by annotated the method name with @RequestMapping(method = RequestMethod.GET).



SimpleFormController

        @Override
 protected Object formBackingObject(HttpServletRequest request)
  throws Exception {
 
  Customer cust = new Customer();
  //Make "Spring MVC" as default checked value
  cust.setFavFramework(new String []{"Spring MVC"});
 
  return cust;
 }



Annotation

        @RequestMapping(method = RequestMethod.GET)
 public String initForm(ModelMap model){
  
  Customer cust = new Customer();
  //Make "Spring MVC" as default checked value
  cust.setFavFramework(new String []{"Spring MVC"});
 
  //command object
  model.addAttribute("customer", cust);
  
  //return form view
  return "CustomerForm";
 }








3. onSubmit() vs RequestMethod.POST
In SimpleFormController, the form submission is handle by the onSubmit() method. In annotation-based, you can do the same by annotated the method name with @RequestMapping(method = RequestMethod.POST).

SimpleFormController

       @Override
 protected ModelAndView onSubmit(HttpServletRequest request,
  HttpServletResponse response, Object command, BindException errors)
  throws Exception {
 
  Customer customer = (Customer)command;
  return new ModelAndView("CustomerSuccess");
 
 }

Annotation

 
 @RequestMapping(method = RequestMethod.POST)
 public String processSubmit(
  @ModelAttribute("customer") Customer customer,
  BindingResult result, SessionStatus status) {
  
  //clear the command object from the session
  status.setComplete(); 
  
  //return form success view
  return "CustomerSuccess";
  
 }


4. referenceData() vs @ModelAttribute
In SimpleFormController, usually you put the reference data in model via referenceData() method, so that the form view can access it. In annotation-based, you can do the same by annotated the method name with @ModelAttribute.

SimpleFormController

 @Override
 protected Map referenceData(HttpServletRequest request) throws Exception {
 
  Map referenceData = new HashMap();
 
  //Data referencing for web framework checkboxes
  List<String> webFrameworkList = new ArrayList<String>();
  webFrameworkList.add("Spring MVC");
  webFrameworkList.add("Struts 1");
  webFrameworkList.add("Struts 2");
  webFrameworkList.add("JSF");
  webFrameworkList.add("Apache Wicket");
  referenceData.put("webFrameworkList", webFrameworkList);
 
  return referenceData;
 }

Spring’s form

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

Annotation

 @ModelAttribute("webFrameworkList")
 public List<String> populateWebFrameworkList() {
  
  //Data referencing for web framework checkboxes
  List<String> webFrameworkList = new ArrayList<String>();
  webFrameworkList.add("Spring MVC");
  webFrameworkList.add("Struts 1");
  webFrameworkList.add("Struts 2");
  webFrameworkList.add("JSF");
  webFrameworkList.add("Apache Wicket");
  
  return webFrameworkList;
 }

Spring’s form

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


5. initBinder() vs @InitBinder
In SimpleFormController, you define the binding or register the custom property editor via initBinder() method. In annotation-based, you can do the same by annotated the method name with @InitBinder.

SimpleFormController

    protected void initBinder(HttpServletRequest request,
  ServletRequestDataBinder binder) throws Exception {
   
  SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
  binder.registerCustomEditor(Date.class, new CustomDateEditor(dateFormat, true));
    }

Annotation

 @InitBinder
 public void initBinder(WebDataBinder binder) {
  SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
  
  binder.registerCustomEditor(Date.class, new CustomDateEditor(dateFormat, true));
 }


From Validation
In SimpleFormController, you 
have to register and map the validator class to the controller class via
 XML bean configuration file, and the validation checking and work flows
 will be executed automatically.

In annotation-based, you have to explicitly execute the validator and define the validation flow in the @Controller class manually. See the different :

SimpleFormController

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

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

Annotation

@Controller
@RequestMapping("/customer.htm")
public class CustomerController{
 
 CustomerValidator customerValidator;
 
 @Autowired
 public CustomerController(CustomerValidator customerValidator){
  this.customerValidator = customerValidator;
 }
 
 @RequestMapping(method = RequestMethod.POST)
 public String processSubmit(
  @ModelAttribute("customer") Customer customer,
  BindingResult result, SessionStatus status) {
  
  customerValidator.validate(customer, result);
  
  if (result.hasErrors()) {
   //if validator failed
   return "CustomerForm";
  } else {
   status.setComplete();
   //form success
   return "CustomerSuccess";
  }
 }
 //...


Full Example
See a complete @Controller example.

package com.mkyong.customer.controller;

import java.sql.Date;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.propertyeditors.CustomDateEditor;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.WebDataBinder;
import org.springframework.web.bind.annotation.InitBinder;
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.bind.support.SessionStatus;

import com.mkyong.customer.model.Customer;
import com.mkyong.customer.validator.CustomerValidator;

@Controller
@RequestMapping("/customer.htm")
public class CustomerController{
 
 CustomerValidator customerValidator;
 
 @Autowired
 public CustomerController(CustomerValidator customerValidator){
  this.customerValidator = customerValidator;
 }
 
 @RequestMapping(method = RequestMethod.POST)
 public String processSubmit(
  @ModelAttribute("customer") Customer customer,
  BindingResult result, SessionStatus status) {
  
  customerValidator.validate(customer, result);
  
  if (result.hasErrors()) {
   //if validator failed
   return "CustomerForm";
  } else {
   status.setComplete();
   //form success
   return "CustomerSuccess";
  }
 }
 
 @RequestMapping(method = RequestMethod.GET)
 public String initForm(ModelMap model){
  
  Customer cust = new Customer();
  //Make "Spring MVC" as default checked value
  cust.setFavFramework(new String []{"Spring MVC"});
  
  //Make "Make" as default radio button selected value
  cust.setSex("M");
  
  //make "Hibernate" as the default java skills selection
  cust.setJavaSkills("Hibernate");
  
  //initilize a hidden value
  cust.setSecretValue("I'm hidden value");
  
  //command object
  model.addAttribute("customer", cust);
  
  //return form view
  return "CustomerForm";
 }
 
 
 @ModelAttribute("webFrameworkList")
 public List<String> populateWebFrameworkList() {
  
  //Data referencing for web framework checkboxes
  List<String> webFrameworkList = new ArrayList<String>();
  webFrameworkList.add("Spring MVC");
  webFrameworkList.add("Struts 1");
  webFrameworkList.add("Struts 2");
  webFrameworkList.add("JSF");
  webFrameworkList.add("Apache Wicket");
  
  return webFrameworkList;
 }
 
 @InitBinder
 public void initBinder(WebDataBinder binder) {
  SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
  
  binder.registerCustomEditor(Date.class, new CustomDateEditor(dateFormat, true));
  
 }
 
 @ModelAttribute("numberList")
 public List<String> populateNumberList() {
  
  //Data referencing for number radiobuttons
  List<String> numberList = new ArrayList<String>();
  numberList.add("Number 1");
  numberList.add("Number 2");
  numberList.add("Number 3");
  numberList.add("Number 4");
  numberList.add("Number 5");
  
  return numberList;
 }
 
 @ModelAttribute("javaSkillsList")
 public Map<String,String> populateJavaSkillList() {
  
  //Data referencing for java skills list box
  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");
  
  return javaSkill;
 }

 @ModelAttribute("countryList")
 public Map<String,String> populateCountryList() {
  
  //Data referencing for java skills list box
  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");
  
  return country;
 }
}

To make annotation work, you have to enable the component auto scanning feature in Spring.

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

 <context:component-scan base-package="com.mkyong.customer.controller" />
 
 <bean class="com.mkyong.customer.validator.CustomerValidator" />
 
  <!-- Register the Customer.properties -->
 <bean id="messageSource"
  class="org.springframework.context.support.ResourceBundleMessageSource">
  <property name="basename" value="com/mkyong/customer/properties/Customer" />
 </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>