How does Spring MVC turn form values into objects?

Question

I'm using Spring 3.0.

I know that when my controller gets invoked, my form bean gets populated by the Spring by evaluating the request parameters and do the necessary conversions.

Let's say I have the following markup

<form action="test">
  <input type="text" name="user.username"/>
  <input type="submit" value="save"/>
</form>

And I have the following controller and classes:

public class MyController
{
  @RequestMapping(...)
  public void myHandler( @ModelAttribute MyForm myForm, ResultBinding result )
  {
    // do something here
  }
}

---

public class MyForm
{
  private User user;

  // Getters and setters included
}

---

public class User
{
  private username;

  // Getters and setters included
}

My problem is that Spring MVC is not using any of my setters to set the properties of my objects. Is there something that I could do to force Spring MVC to use the setters to set the properties of my objects? Where in the Spring documentation that says how Spring does this?

Answer 1

Have you tried using spring form tag library?
http://docs.spring.io/spring/docs/2.0.x/reference/spring-form.tld.html#spring-form.tld.form

Answer 2

Spring MVC为此使用PropertyEditorSupport的实现。

Answer 3

You need to annotate your method parameter with @ModelAttribute :

public void myHandler( @ModelAttribute("myForm") MyForm myForm, ResultBinding result )

And have a method to provide an instance of your model object:

@ModelAttribute("myForm")
public MyForm getMyForm() {
  return new MyForm();
}

See this: http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/mvc.html#mvc-ann-modelattrib