非IOC方式獲取web對象

package com.hd.action;
import java.util.Map;
import javax.servlet.ServletContext;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import org.apache.struts2.ServletActionContext;
import com.opensymphony.xwork2.ActionContext;

/**
 * 獲取web對象
 *     1.通過非IOC方式獲取
 *         1）直接方式獲取web對象
 *         2）間接方式獲取web對象
 * @author think
 *
 */
public class UserAction {

    public String add(){
        /*
         * 1).直接方式獲取
         *     通過類ServletActionContext調用提供的方法獲取
         */
        //獲取request對象
        HttpServletRequest req = ServletActionContext.getRequest();
        //獲取session對象
        HttpSession session = req.getSession();
        //獲取response
        HttpServletResponse res = ServletActionContext.getResponse();
        //獲取applicationContext
        ServletContext appc = ServletActionContext.getServletContext();
        
        //獲取jsp頁面傳過來的參數
        String username = req.getParameter("username");
        String pwd = req.getParameter("pwd");
        
        System.out.println("賬號：" + username);
        System.out.println("密碼：" + pwd);
        
        //往jsp頁面傳值
        req.setAttribute("msg", "來自req中的數據");
        session.setAttribute("msg", "來自session中的數據");
        appc.setAttribute("msg", "來自applicationContext中的數據");
        
        return "success";
    }
    
    
    public String update(){
        /*
         * 2）間接方式獲取
         *         一般用來存儲數據
         */
        //獲取request對象
        ActionContext req = ActionContext.getContext();
        //獲取session對象
        Map<String, Object> session = req.getSession();
        //獲取applicationContext
        Map<String, Object> appc = req.getApplication();
        
        req.put("msg", "間接方式獲取req");
        session.put("msg", "間接方式獲取session");
        appc.put("msg", "間接方式獲取ApplicationContext");
        
        return "success";
    }
    
}