Question on @RequestParam conversions

[MarkyBoy]

I have some questions regarding RequestParam conversions.

For the most part I have simple conversions working however when it comes to more complex objects things arent working the way they would seem.

For example. How are lists/arrays handled when the type is any other type of object other than string?

@ResponseBody
RequestMapping(value = "/foo")
public String foo(@RequestParam(value ="bar", required=true) List<Integer> fooIds) {
...
}

http://localhost:8080/spring/foo?bar=1,2,3
or
http://localhost:8080/spring/foo?bar=1&bar=2&bar=3

Whenever I try to access the list of fooIds as Integers I get a Cannot cast from String to Integer exceptions. I would have thought this simple conversion would be accomplished. If i change the type to List<String> everything is works as expected.

Now for more complex objects:

public Foo {
  public Foo(List<String> bars) {
    .....
  }
}

@ResponseBody
RequestMapping(value = "/foo")
public String foo(@RequestParam(value ="bar", required=true) Foo myFoo) {
...
}

Now in this example I would think that the Foo class would receive a List<String> as a constructor argument but it doesn't'. If i change or add a constructor that expects a single string then it will work. How would I handle this situation?

Obviously I am missing something so can someone please clarify these issues for me?

Thanks for any help!

[MarkyBoy]

Forgot to mention. I am using Spring 3.0.5