ActionMapping actionMapping = null;
    ActionForm actionForm = null; //初始化ActionForm
    HttpServletRequest servletRequest = null; //Request实例
    HttpServletResponse servletResponse = null; //Response实例
    ActionForward expectedReturn = null; //异常实例    //转发返回结果测试
    ActionForward actualReturn = loginAction.execute(actionMapping, actionForm,
        servletRequest, servletResponse);actionMapping, actionForm, servletRequest, servletResponse 都是null;
在loginAction.execute会报空指针异常的.