JavaWeb HttpSession

/**
 * 使用session共享数据
 */
public class SessionDemo1 extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //使用session共享数据
        //1.获取session
        HttpSession session = req.getSession();
        //2.存储数据
        session.setAttribute("msg0","HelloSession");
    }
}

/**
 * 获取session共享的数据
 */
public class SessionDemo2 extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //使用session获取数据
        //1.获取session
        HttpSession session = req.getSession();
        //2.获取数据
        Object msg = session.getAttribute("msg0");
        System.out.println(msg);
    }
}

/**
 * 使用Cookie将Session保存到浏览器，且关闭浏览器再打开后不会消失
 */
public class SessionDemo3 extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1.获取Session
        HttpSession session = req.getSession();
        System.out.println(session);

        //期望客户端关闭后，session也能相同
        Cookie c = new Cookie("JSESSIONID",session.getId());
        resp.addCookie(c);
    }

}