Struts2 获取参数的操作方式

以下方式能拿到上下文中的值:

import javax.servlet.http.HttpServletRequest;
import org.apache.struts2.ServletActionContext;
HttpServletRequest request=(HttpServletRequest)ServletActionContext.getRequest();
request.getSession().getAttribute("userId").toString()
 

以下两种方式能拿到struts2前台传递到后台的参数值:
String id = this.getRequest().getParameter("id");
String ids = this.httpServletRequest.getParameter("id");