Session的使用

Posted 2021-05-12 晓龙爱Java

package com.wang.servlet;

import com.wang.pojo.Person;

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

public class SessionDemo01 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //解决乱码问题
        resp.setCharacterEncoding("utf-8");
        req.setCharacterEncoding("utf-8");
        resp.setContentType("text/html;charset=utf-8");
        //得到Session
        HttpSession session = req.getSession();
        //给Session中存东西
        session.setAttribute("name","晓晓"));
        //获取Session的ID
        String sessionId = session.getId();

        //判断Session是不是新创建
        if (session.isNew()){
            resp.getWriter().write("session创建成功,ID:"+sessionId);
        }else {
            resp.getWriter().write("session已经在服务器中存在了,ID"+sessionId);
        }



    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        super.doPost(req, resp);
    }
}

得到Session

package com.wang.servlet;

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

public class SessionDemo02 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //解决乱码问题
        resp.setCharacterEncoding("utf-8");
        req.setCharacterEncoding("utf-8");
        resp.setContentType("text/html;charset=utf-8");
        //得到Session
        HttpSession session = req.getSession();

        String name = (String) session.getAttribute("name");

        System.out.println(name);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        super.doPost(req, resp);
    }
}

手动删除Session

package com.wang.servlet;

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

public class SessionDemo03 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        HttpSession session = req.getSession();
        session.removeAttribute("name");
        session.invalidate();//手动删除session
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        super.doPost(req, resp);
    }
}

设置Session默认的失效时间 在web.xml添加

<!--  设置Session默认的失效时间  -->
    <session-config>
<!--    5分钟后Session自动失效,以分钟为单位    -->
        <session-timeout>5</session-timeout>
    </session-config>