Spring 表单处理

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>

Download Source Code

Download it – SpringMVC-Form-Handling-Annotation-Example.zip (12KB)