Come acquisire un oggetto JSON in Action Struts 2

[AspGuru]

Ciao a tutti,
vorrei inviare un oggetto JSON da Jquery a un Action in struts 2 tramite Jquery.
Ecco il mio codice, qualche soluzione?

Grazie anticipatamente

Client Code:

$(document).ready(function () {	  
	$('a.submit_json_form').live('click',function(){
		var jsonUser = {
				username: $('#username').val(),
				password: $('#password').val(),
				idRole: $('#idRole').val()
		};											
		$.ajax({
			type: "POST",
			url: "/MyProject/UserNew.action?method=newUser",
			data: JSON.stringify (jsonUser),
			contentType: 'application/json; charset=utf-8',
			dataType: 'json',
			success: function(msg){	        	
				$('#result').html($.trim(msg));
			},
			error: function(e){
				//error
			}
		});
	});
});

Server Code:

 public class UserAction extends ActionSupport implements  ServletResponseAware, ServletRequestAware{    
	private String username = null;
	private String password = null;
	private String idRole = null;
	public String getidRole() {
		return idRole;
	}
	public void setIdRuolo(String idRole) {
		this.idRole = idRole;
	}
	public String getUsername() {
		return username;
	}
	public void setUsername(String username) {
		this.username = username;
	}
	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}

	public String newUser() throws Exception{
		logger.info("UserAction, method=newUser");
		//HOW TO GET JSON DATA FROM JQUERY AJAX POST???

		return "succesUser";
	}
}