JavaWeb-Cookie与显示商品浏览记录案例

客户端的会话技术:cookie
				
	A.Cookie API

		1.创建Cookie对象.
		    Cookie cookie=new Cookie(String name,String value);
					
		2.获取cookie名称
			cookie.getName();
						
		3.获取cookie值
			cookie.getValue();
						
		4.设置cookie为持久化cookie。
			setMaxAge	
						
		cookie默认是会话级别，它保存在浏览器的缓存中，当关闭浏览器后，缓存中的内容清空。
						
		如果cookie使用了setMaxAge进行设置，这时cookie就是持久化的cookie。当浏览器关闭，
        持久化的cookie还存在。当重新打开浏览器，在发送请求，会将持久化的cookie.
			带到服务器端.前提:cookie没有过期.
						
		如果要删除cookie持久化文件，只需要设置setMaxAge(0) 如果值为负数，那么会在浏览器
        关闭后删除cookie。
						
		5.用于设置当前的cookie在什么样的uri访问时才会被带到服务器端.
			setPath
			练习时可以简单写在  setPath("/");
													
						
	B.关于将cookie带回到浏览器端.
		response.addCookie(Cookie c);
					
	C.在服务器端得到cookie
		Cookie[] cs=request.getCookies();

商品浏览记录实例

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
	String path = request.getContextPath();
	String basePath = request.getScheme() + "://"
			+ request.getServerName() + ":" + request.getServerPort()
			+ path + "/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">

<title>显示商品</title>

<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->

</head>

<body>
	<a href="/HelloWeb/cookie/history.jsp">查看浏览记录</a>
	<hr>
	<a href="/HelloWeb/Goods?id=1">西游记</a>
	<br>
	<a href="/HelloWeb/Goods?id=2">红楼梦</a>
	<br>
	<a href="/HelloWeb/Goods?id=3">水浒传</a>
	<br>
	<a href="/HelloWeb/Goods?id=4">三国演义</a>
	<br>
</body>
</html>

<%@page import="demo.utils.CookieUtils"%>
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
	String path = request.getContextPath();
	String basePath = request.getScheme() + "://"
			+ request.getServerName() + ":" + request.getServerPort()
			+ path + "/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">

<title>显示商品浏览记录</title>

<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->

</head>

<body>
	<%
		String[] books = { "西游记", "红楼梦", "水浒传", "三国演义" };

		//得到history这个cookie
		Cookie history = CookieUtils.getCookieByName(request.getCookies(),
				"history");
		if (history != null) {
			//得到history的vlaue值
			String value = history.getValue();
			String[] ids = value.split("-");
			for (int i = 0; i < ids.length; i++) {
				int id = Integer.parseInt(ids[i]) - 1;
	%>
	<%=books[id]%><br>
	<%
		}
		} else {
			out.print("无浏览记录");
		}
	%>
</body>
</html>

package demo.cookie;

import java.io.IOException;
import java.lang.reflect.Array;
import java.util.Arrays;

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

import demo.utils.CookieUtils;

public class GoodsServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		// 得到请求的参数
		String id = request.getParameter("id");

		// 得到history名称的cookie
		Cookie[] cs = request.getCookies();
		Cookie history = CookieUtils.getCookieByName(cs, "history");
		String ids = null;
		// 如果history为null,说明第一次访问
		if (history == null) {
			ids = id;
		} else {
			// 不是第一次
			// 得到cookie中的value
			ids = history.getValue();
			// 考虑重复
			if (!Arrays.asList(ids.split("-")).contains(id)) {
				ids += "-" + id;
			}

		}
		// 存储到cookie中
		history = new Cookie("history", ids);
		// 持久化
		// history.setMaxAge(30);

		// 再返回到响应中
		response.addCookie(history);
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}

}

JavaWeb-Cookie与显示商品浏览记录案例

猜你喜欢