Unit07： 状态管理-Session

　　　　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();
    }
    
}

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;

public class LoginServlet extends HttpServlet {

    //相当于MainServlet.login()
    @Override
    protected void service(
        HttpServletRequest req, 
        HttpServletResponse res) throws ServletException, IOException {
        //接收参数
        String code = req.getParameter("code");
        //存入session
        //第一次访问session时服务器自动创建它,
        //当前登录就是第一次访问,就创建session
        HttpSession session = req.getSession();
        //session中可以存任意类型的数据
        session.setAttribute("code", code);
        //服务器向浏览器发送响应时,会自动创建
        //一个cookie,并将SID存入此cookie,再
        //将此cookie发送给浏览器.服务器会将
        //此cookie的有效路径设置为项目.
    }

}

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">
  <display-name>jsp4</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  
  <servlet>
      <servlet-name>login</servlet-name>
      <servlet-class>web.LoginServlet</servlet-class>
  </servlet>
  <servlet-mapping>
      <servlet-name>login</servlet-name>
      <url-pattern>/main/login</url-pattern>
  </servlet-mapping>
  
  <servlet>
      <servlet-name>findCost</servlet-name>
      <servlet-class>web.FindCostServlet</servlet-class>
  </servlet>
  <servlet-mapping>
      <servlet-name>findCost</servlet-name>
      <url-pattern>/cost/find</url-pattern>
  </servlet-mapping>
  
  <!-- 配置session的ID释放时长 -->
  <session-config>
      <session-timeout>1</session-timeout>
  </session-config>
  
</web-app>