JavaWeb--会话Session

Session：服务端的会话跟踪技术，将数据保存到服务端
JavaEE提供HttpSession接口，来实现一次会话的多次请求间数据共享功能
使用：
①获取Session对象
HttpSession session = request.getSession();
②Session对象功能
void setAttribute(String name,Object o);//存储数据到session域中
Object getAttribute(String name)：根据key获取值
void removeAttribute(String name)：根据key,删除该键值对

package test.SessionTest;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;

@WebServlet("/ServletSession")
public class ServletSession extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获取Session对象
        HttpSession session = request.getSession();
        //存储数据
        session.setAttribute("username","zs");
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}

package test.SessionTest;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;

@WebServlet("/ServletSession1")
public class ServletSession1 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获取数据
        HttpSession session = request.getSession();

        //获取值
        Object username = session.getAttribute("username");
        System.out.println(username);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}