JAVA---session

package servlet;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;

/**
 * 
 * 
 * @create 2022-05-01 16:28
 */
public class SessionServlet extends BaseServlet {

    protected void createOrGetSession(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //创建和获取session会话对象
        HttpSession session = req.getSession();
        //判断当前Session会话，是否是新创建出来的
        boolean isNew = session.isNew();
        //获取Session会话的唯一标识id
        String id = session.getId();

        resp.getWriter().write("得到的session，它的id是：" + id + "<br/>");
        resp.getWriter().write("这个Session是否是新创建的" + isNew + "<br/>");

    }

    protected void setAttribute(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.getSession().setAttribute("key1", "value1");
        resp.getWriter().write("向session中保存了数据");
    }
    protected void getAttribute(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        Object key1 = req.getSession().getAttribute("key1");
        resp.getWriter().write("从session中获取出key1的数据是:"+key1);
    }
    protected void defaultLife(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //获取session的默认超时时长
        int maxInactiveInterval = req.getSession().getMaxInactiveInterval();
        
        resp.getWriter().write("Session的默认超时时长为："+maxInactiveInterval+"秒");
    }
    protected void life3(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //获取session对象
        HttpSession session = req.getSession();
        //设置当前Session3秒后超时
        session.setMaxInactiveInterval(3);
        resp.getWriter().write("当前sessin已经设置为3秒后超时");
    }
    protected void deleteNow(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //先获取session对象
        HttpSession session = req.getSession();
        
        //让session会话马上超时
        session.invalidate();
        
        resp.getWriter().write("session已经设置为超时（无效）");
    }
    
    


}