Spring 表单处理

Dear 丶 2021-09-19 10:30 308阅读 0赞

## 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*

*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" />
     
     	
    	<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)

==============================================================================

本文转自被遗忘的博客园博客，原文链接：http://www.cnblogs.com/rollenholt/archive/2012/12/27/2836249.html，如需转载请自行联系原作者

[SpringMVC-Form-Handling-Annotation-Example.zip]: http://www.mkyong.com/wp-content/uploads/2010/08/SpringMVC-Form-Handling-Annotation-Example.zip