struts2對HttpServletRequest、HttpSession、ServletContext進行了封裝，
構造了三個Map物件來替代這三個物件。在action中獲取這三個物件的方法有
三種。
1、通過ActionContext獲取

        ActionContext ac = ActionContext.getContext();
        Map<String,Object> application = ac.getApplication();
        Map<String, Object> session = ac.getSession
 
();

        ac.put("req", "req");
        application.put("application", "application");
        session.put("session", "session");

2、通過ServletActionContext獲取

        HttpServletRequest request = ServletActionContext.getRequest();
        request.setAttribute("req", "req");
        request.getSession
 
().setAttribute("session", "session");
        request.getServletContext().setAttribute("application", "application");

3、通過實現SessionAware，ApplicationAware，RequestAware介面，在實現方法內賦值獲取

public class testAction  implements RequestAware,SessionAware,ApplicationAware{

    private Map<String, Object> request;
    private
 
 Map<String, Object> session;
    private Map<String, Object> application;

    public String execute(){
        System.out.println("struts");

        request.put("req", "request");
        application.put("application", "application");
        session.put("session", "session");
        return "success";
    }
    @Override
    public void setApplication(Map<String, Object> application) {
                this.application = application;
    }
    @Override
    public void setSession(Map<String, Object> session) {
            this.session = session;
    }
    @Override
    public void setRequest(Map<String, Object> request) {
                this.request = request;
    }
}

在action後的跳轉頁面檢測值

request = ${requestScope.req}<br>
session = ${sessionScope.session}<br>
application = ${applicationScope.application}<br>