ActionForm 与 Action 中的验证

ActionForm:

public ActionErrors validate(
    ActionMapping mapping,
    HttpServletRequest request) ...{

    ActionErrors errors=new ActionErrors();
    errors.add("userId",new ActionMessage("error.userid.exists"));
    return errors;
}

 

Action:

public ActionForward execute(
        ActionMapping mapping,
        ActionForm form,
        HttpServletRequest request,
        HttpServletResponse response)
        ...{
        ActionMessages errors=new ActionMessages();
        errors.add(    ActionMessages.GLOBAL_MESSAGE,
            new ActionMessage("error.sort.havetopic"));

            this.saveErrors(request,errors);
            return mapping.findForward("fail");
        }
        return mapping.findForward("other");
    }