Unit07： 状态管理-Session

 web

 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 FindCostServlet extends HttpServlet {

    //相当于MainServlet.findCost()
    @Override
    protected void service(
        HttpServletRequest req, 
        HttpServletResponse res) throws ServletException, IOException {
        //获取旧的session,此session是在
        //登录请求中服务器自动创建的.
        HttpSession session = req.getSession();
        String code = (String) 
            session.getAttribute("code");
        //输出数据
        res.setContentType(
            "text/html;charset=utf-8");
        PrintWriter out = res.getWriter();
        out.println(code);
        out.close();
    }
    
}

FindCostServlet.java