16 域对象3 Session域

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 Session域

有效范围

单次会话内有效,可以跨多个请求

生命周期

创建 会话的产生,第一次发生请求,会话的开始

使用 本次会话之内,浏览器和服务器之间发生多次请求和响应有效

销毁 会话结束,如:浏览器失去JSESSIONID、到达最大不活动时间、手动清除

测试代码

Session域中放入数据

package com.msb.testSession;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
 * @Author: Ma HaiYang
 * @Description: MircoMessage:Mark_7001
 */
@WebServlet(urlPatterns = "/addToSession.do")
public class Servlet1 extends HttpServlet {
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // 向Session域中添加数据
        HttpSession session = req.getSession();
        List<String> x=new ArrayList<>();
        Collections.addAll(x, "a","b","c");
        session.setAttribute("list", x);
        session.setAttribute("gender","boy");
        session.setAttribute("gender","girl");
        session.setAttribute("name","晓明");
        // 重定向
        resp.sendRedirect("readFromSession.do");
    }
}

 

从Session域中读取数据

 

package com.msb.testSession;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
import java.util.List;
/**
 * @Author: Ma HaiYang
 * @Description: MircoMessage:Mark_7001
 */
@WebServlet(urlPatterns="/readFromSession.do")
public class Servlet2 extends HttpServlet {
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        HttpSession session = req.getSession();
        // 移除域中的互数据
        //session.removeAttribute("gender");
        // 从request域中读取数据
        List<String> list =(List<String>) session.getAttribute("list");
        System.out.println(list);
        System.out.println(session.getAttribute("gender"));
        System.out.println(session.getAttribute("name"));
        //获取Request中的请求参数
        System.out.println(req.getParameter("username"));
        System.out.println(req.getParameter("password"));
    }
}

 

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