jsp之session的使用

LoginServlet

package web;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
/**
 * 用session演示login()
 */
public class LoginServlet extends HttpServlet {

    @Override
    protected void service(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
        //接收账号
        String code = req.getParameter("code");
        //存入session
        //session是存储在服务器上的对象,
        //它的内部可以存储任意类型的数据.
        HttpSession session = req.getSession();
        session.setAttribute("code", code);
        //响应时服务器会自动创建cookie,将
        //session的ID通过cookie发送给浏览器.
        //Cookie c = new Cookie("JSESSIONID",seesion.getId());
        
    }
    
    
    
}

IndexServlet

package web;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class IndexServlet extends HttpServlet {

    @Override
    protected void service(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
        //由于本次请求浏览器传入了SID,
        //服务器就根据此SID找到那个旧的
        //session,可以从中读取之前存的数据.
        HttpSession session = req.getSession();
        String code = (String)session.getAttribute("code");
        //将此数据显示给浏览器
        res.setContentType("text/html;charset=utf-8");
        PrintWriter out = res.getWriter();
        out.println(code);
        out.close();
        
    }
    
    
    
}