In my previous post, I showed how to convert a Spring web controller class to use the @Controller annotation. In this post, I aim to show how forms in a Spring MVC application can also be converted to using annotations.

Forms in Spring are typically modelled by extending the org.springframework.web.servlet.mvc.SimpleFormController class, but using Spring annotations, they can also be simplified and defined by the @Controller annotation.Without annotations, a SimpleFormController would be defined as below as in both a Java class and as a bean in XML.

import org.springframework.web.servlet.mvc.SimpleFormController 
   
public class PriceIncreaseFormController extends SimpleFormController { 
   
    public ModelAndView onSubmit(Object command) { 
        // Submit the form 
    } 
       
    protected Object formBackingObject(HttpServletRequest request) 
        throws ServletException { 
        // Initialize the form 
    } 
}

<bean name="/priceincrease.htm" class="springapp.web.PriceIncreaseFormController"> 
    <property name="commandName" value="priceIncrease"/> 
    <property name="commandClass" value="springapp.service.PriceIncrease"/> 
    <property name="validator"> 
        <bean class="springapp.service.PriceIncreaseValidator"/> 
    </property> 
    <property name="formView" value="priceincrease"/> 
    <property name="successView" value="home.htm"/> 
</bean>

 To convert the class to use annotations, we need to add an @Controller and @RequestMapping annotation.  We can then define a simple POJO controller that does not need to extend Spring's classes.

@Controller 
@RequestMapping("/priceincrease.htm") 
public class PriceIncreaseFormController { 
  
    @Autowired
    private PriceIncreaseValidator priceIncreaseValidator; 
   
    @RequestMapping(method=RequestMethod.POST) 
    public String onSubmit(@ModelAttribute("priceIncrease")PriceIncrease priceIncrease, 
        BindingResult result) { 
           
        int increase = priceIncrease.getPercentage(); 
        priceIncreaseValidator.validate(increase, result); 
        if (result.hasErrors()) 
            return "priceIncrease"; 
           
        // Validator has succeeded. 
        // Perform necessary actions and return to success page. 
        return "redirect:home.htm"; 
    } 
       
    @RequestMapping(method=RequestMethod.GET) 
    public String initializeForm(ModelMap model) { 
        // Perform and Model / Form initialization
        Map<Integer, String> priority = new LinkedHashMap<Integer, String>();
        priority.put(1, "Low");
        priority.put(2, "Normal");
        priority.put(3, "High");
  
        model.addAttribute("priorityList", priority);
   
        return "priceincrease"; 
    } 
   
    // Other getters and setters an needed. 
}

From http://www.davidsalter.co.uk/1/post/2011/04/converting-a-spring-simpleformcontroller-into-an-controller.html