Jersey Restful API Validation

Jersey Restful API Validation

how can i validate user name and password using jersey restful API.
Here is the code Below:
I tried using the HttpRequest and HttpResponse
@POST
@Path("/login")
@Consumes(MediaType.APPLICATION_FORM_URLENCODED)
@Produces(MediaType.APPLICATION_JSON)
public String postLoginJson(@FormParam("userName") String userName,
@FormParam("password") String password) {
String user = null;
try {
user = userObjectJson();
} catch (JSONException e) {
e.printStackTrace();
}
System.out.println("User Name = " + userName);
System.out.println("Password = " + password);
return user;
}