Add Validator to Annotation defined controller

[kulkarni_ash]

I am trying to use annotation and have a question about validating my form,
I have defined

<annotation-driven />

in my xml file
and my controller is as below, if i want to validate my form so that name cannot be blank

My Jsp page

<f:form method="post" action="displayusermessage" commandName="usermessage">
</f:form>

UserMessage bean

public class UserMessage {
	    
	    private String name;
	    private String message;
	 
	    public String getName() {
	        return name;
	    }
	    public void setName(String name) {
	        this.name = name;
	    }
	    public String getMessage() {
	        return message;
	    }
	    public void setMessage(String message) {
	        this.message = message;
	    }
	}

@Controller
public class HomeController {
@RequestMapping(value = "/displayusermessage", method = RequestMethod.POST)
    public String display(@ModelAttribute("usermessage") UserMessage usermessage, Model model) {
       //validate usermessage, if name is blank then send back to same page, or else send to success page
//how do i add validation here
       
        model.addAttribute("usermessage", usermessage);
        return "success"
    }
}

[ChrisInSeattle]

Ash,

I haven't tried this recommended solution so it may be incorrect... However, this is where I'd start if I were in your shoes. This recommended solution started HERE

You UserMessage Beans:

  
import org.springmodules.validation.bean.conf.loader.annotation.handler.Length;  
import org.springmodules.validation.bean.conf.loader.annotation.handler.NotBlank;

public final class UserMessage {  
      
    @NotBlank  
    @Length(max = 80)  
    private String name; 

    public String getName() {  
        return name;  
    }  

    public void setName(String name) {  
        this.name = name;  
    }
}

Your Controller:

@Controller  
public final class HomeController {
    @Autowired  
    private Validator validator;  

    @RequestMapping(value = "/displayusermessage", method = RequestMethod.POST)      
    public String post(@ModelAttribute("userMessage") UserMessage userMsg, BindingResult result) {  
        validator.validate(userMsg, result);

        if (result.hasErrors()) { return "form"; }

        // Use the redirect-after-post pattern to reduce double-submits.  
        return "redirect:thanks";
    }
}

Good luck!