How to Change the values of Text fields on the change of option box value

Hiii Guys, I am working on a project which is using Spring MVC and Hibernate framework. My problem is that I am working on a Form and in the form a Option Box working. I want to change a text field value on change of option box value. I already Try this :-

<script type="text/javascript" >
    $(document).ready(function(){
        $("#venderid").change(function(){
            $.getJSON("getVenderById.htm", {venderId: $(this).val()},
            function(vender){
                var data = JSON.parse(vender);
                var mail = data.mail;
                $("#mail").html(mail);
            }
);
        });
    });

</script>

Vender.java

public class Vender {
   private Integer venderid;
     private String vendername;
     private String email;
     private String contact;
    //Setters and getters
}

Controller:-

@RequestMapping(value = "/getVenderById.htm")
    @ResponseBody
    public ModelAndView getVender(@RequestParam("venderId") int vId){
        ModelAndView mav = new ModelAndView();
        mav.addObject("vender", venderDAO.findById(vId));
        System.out.println("=========Ajax Calling============");
        return mav;
    }

Every thing is working fine but how to filled the textbox of e-mail according vender id . Is there any mistake in Callback function , or how to utilize the value of vender object. And one more thing on Apache server console window ========Ajax Calling======= printing means data is coming from the database. But how do i utilize it please help . And thanks in advance.