在struts2的action中操作域对象(request、session)

在struts2的Action中，操作域对象一共有三种方式：
1.ActionContext(与servelt API无关联):

//相当于request
ActionContext.getContext().put("userName", user.getUserName());
//相当于session
ActionContext.getContext().getSession().put("userName", user.getUserName());
//相当于Application
ActionContext.getContext().getApplication().put("userName", user.getUserName());
//parameter
String name = (String) ActionContext.getContext().getParameters().get("userName");

2.实现ServletRequestAware,ServletResponseAware接口，通过注入的方式，获取request、response:

private HttpServletResponse response;

private HttpServletRequest request;

@Override
public void setServletResponse(HttpServletResponse response) {
this.response = response;
}

@Override
public void setServletRequest(HttpServletRequest request) {
this.request = request;
}

3.通过ServletActionContext提供的静态方法获得request、response:

HttpServletRequest request = ServletActionContext.getRequest();