16 域对象3 Session域

短命女 2023-09-30 20:22 1阅读 0赞

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");
        }
    }

![c4bb6186c48e9b397b8461d2de74c070.gif][]

![48530c8cb5065b413fab911064ceee91.gif][]

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"));
        }
    }

![a4f44bbe6c6cec75fb6bc04e20a15409.gif][]

![f4e364d5dbed849f4aff7507fb24d130.gif][]

[c4bb6186c48e9b397b8461d2de74c070.gif]: https://img-blog.csdnimg.cn/img_convert/c4bb6186c48e9b397b8461d2de74c070.gif
[48530c8cb5065b413fab911064ceee91.gif]: https://img-blog.csdnimg.cn/img_convert/48530c8cb5065b413fab911064ceee91.gif
[a4f44bbe6c6cec75fb6bc04e20a15409.gif]: https://img-blog.csdnimg.cn/img_convert/a4f44bbe6c6cec75fb6bc04e20a15409.gif
[f4e364d5dbed849f4aff7507fb24d130.gif]: https://img-blog.csdnimg.cn/img_convert/f4e364d5dbed849f4aff7507fb24d130.gif