示例：显示上次访问商品记录（四）

一、显示上次浏览商品的实现过程图

二、要实现的功能如下：

三、实现代码

book.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>书籍列表</title>
</head>
<body>
<table border="1px">
	<caption>四大名著</caption>
	<tr>
		<td>水浒传</td>
		<td><a href="<%=request.getContextPath() %>/bookServlet?id=1">浏览</a></td>
	</tr>
	<tr>
		<td>红楼梦</td>
		<td><a href="<%=request.getContextPath() %>/bookServlet?id=2">浏览</a></td>
	</tr>
	<tr>
		<td>三国演义</td>
		<td><a href="<%=request.getContextPath() %>/bookServlet?id=3">浏览</a></td>
	</tr>
	<tr>
		<td>西游记</td>
		<td><a href="<%=request.getContextPath() %>/bookServlet?id=4">浏览</a></td>
	</tr>
</table>
<hr>
<a href="show.jsp">浏览记录</a>
</body>
</html>

show.jsp

<%@page import="com.it.utils.CookieUtil"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<%
	String[] books = {"水浒传", "红楼梦", "三国演义", "西游记"};
	
	Cookie cookie = CookieUtil.getCookie("bookHistory", request.getCookies());
	
	if(cookie == null){
	%> 记录为空 <%
	} else {
		String[] ids = cookie.getValue().split("-");
		for(String id : ids){
			%> 浏览的图书为：<%=books[Integer.parseInt(id)-1]%><br><%
			
		}
	}



%>
	
</body>
</html>

com.it.utils.CookieUtil

package com.it.utils;

import javax.servlet.http.Cookie;

public class CookieUtil {
	public static Cookie getCookie(String name, Cookie[] cookies) {
		if(null == cookies || cookies.length == 0) {
			return null;
		} else {
			for(Cookie cookie : cookies) {
				if(name.equals(cookie.getName())) {
					return cookie;
				}
			}
		}
		return null;
	}
}

com.it.servlet.cookie.BookServlet

package com.it.servlet.cookie;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.List;

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 com.it.utils.CookieUtil;

public class BookServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//得到浏览书籍的id
		String id = request.getParameter("id").trim();
		//得到Cookie
		Cookie cookie = CookieUtil.getCookie("bookHistory", request.getCookies());
		
		if(cookie == null) {
			cookie = new Cookie("bookHistory", id);
		}else {
			String value = cookie.getValue();//1-3-4
			List<String> ids = Arrays.asList(value.split("-"));
			if(!ids.contains(id)) {
				value += "-" + id;
			}
			cookie = new Cookie("bookHistory", value);
		}
		
		response.addCookie(cookie);
		response.sendRedirect(request.getContextPath() + "/book.jsp");
	}

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

		doGet(request, response);
	}

}

示例：显示上次访问商品记录（四）

一、显示上次浏览商品的实现过程图

三、实现代码

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