基础4——会话技术

1.简介

2.Cookie

流程：

案例：返回上一次进入会话的时间

原理：

代码：

3.Session

案例：

1）输入框html

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<center>
<h1>商品列表</h1>
<a href ="/download/asd?name=杯子">杯子</a><br/>
<a href ="/download/asd?name=书包">书包</a><br/>
<a href ="/download/asd?name=笔记本">笔记本</a>
</center>

</body>
</html>

2）添加数据的servlet

package com.anli;

import java.awt.List;
import java.io.IOException;
import java.util.ArrayList;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
* Servlet implementation class AddCartServlet
*/

@WebServlet("/asd")

public class AddCartServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding("utf-8");

//1.获取到商品的信息
String name=request.getParameter("name");
//2.需要保存商品信息到session
HttpSession session=request.getSession();
ArrayList list=(ArrayList)session.getAttribute("list");
if(list==null) {
list=new ArrayList();
}
list.add(name);
session.setAttribute("list", list);

Cookie cookie=new Cookie("JSESSIONID",session.getId());
cookie.setMaxAge(60*60*24);
cookie.setPath("/download");
response.addCookie(cookie);

}

/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}

}

3）显示挑选的商品的购物车servlet

package com.anli;

import java.io.IOException;
import java.util.ArrayList;

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

/**
* Servlet implementation class GetCartServlet
*/
@WebServlet("/GetCartServlet")
public class GetCartServlet extends HttpServlet {
private static final long serialVersionUID = 1L;


/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//下面那个方法内部已经封装了获取cookie从而在服务器端获取对应的session的逻辑
HttpSession session=request.getSession();
ArrayList<String> list=(ArrayList<String>)session.getAttribute("list");
response.setContentType("text/html;charset=utf-8");
for(String s:list) {
response.getWriter().write(s+"<br/>");
}
}

/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}

}

posted @ 2017-08-27 19:11 鹏达君阅读(157) 评论(0) 收藏举报

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基础4——会话技术

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