利用cookie显示商品的浏览记录

需求介绍：利用cookie技术，在“你曾经看过的商品 ”列表中显示顾客最新浏览的3件商品（最后一次浏览的在最上边，以此类推）。

主页面为：IndexInf.java

package CookieDemo;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.LinkedHashMap;
import java.util.Map;

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

public class IndexInf extends HttpServlet
{
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException
	{
		//解决中文乱码问题
		response.setCharacterEncoding("UTF-8");
		response.setContentType("text/html;charset=UTF-8");
		PrintWriter out = response.getWriter();
		
		//输出所有商品
		out.write("网站商品如下 ： 
");
		Map map = Db.getAll();
		for(Map.Entry entry : map.entrySet())
		{
			Book book = entry.getValue();
			out.print(""+book.getName()+"
");
		}
		
		//显示用户看过的商品
		out.print("
你曾经看过的商品 : 
");
		Cookie[] cookies = request.getCookies();
		for(int i=0;cookies!=null && i");
				}
			}
		}
	}

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

}

//用类来简单模拟数据库
class Db
{
	private static Map map = new LinkedHashMap(); 
	static
	{
		map.put("1",new Book("1","Java开发","赵钱","好书啊。"));
		map.put("2",new Book("2","JavaWeb开发","孙李","好书啊。"));
		map.put("3",new Book("3","Jdbc开发","周武","好书啊。"));
		map.put("4",new Book("4","Spring开发","郑王","好书啊。"));
		map.put("5",new Book("5","Android开发","马六","好书啊。"));
	}
	public static Map getAll()
	{
		return map;
	}
}

//创建Book类
class Book
{
	private String id;
	private String name;
	private String author;
	private String description;
	
	public Book()
	{
		super();
	}

	public Book(String id, String name, String author, String description)
	{
		super();
		this.id = id;
		this.name = name;
		this.author = author;
		this.description = description;
	}

	public String getId()
	{
		return id;
	}
	
	public void setId(String id)
	{
		this.id = id;
	}
	
	public String getName()
	{
		return name;
	}
	
	public void setName(String name)
	{
		this.name = name;
	}
	
	public String getAuthor()
	{
		return author;
	}
	
	public void setAuthor(String author)
	{
		this.author = author;
	}
	
	public String getDescription()
	{
		return description;
	}
	
	public void setDescription(String description)
	{
		this.description = description;
	}	
}

显示商品信息页面为ShowGoodsInf.java：

package CookieDemo;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedList;
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;

public class ShowGoodsInf extends HttpServlet
{

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException
	{
		//解决中文乱码问题
		response.setCharacterEncoding("UTF-8");
		response.setContentType("text/html;charset=UTF-8");
		PrintWriter out = response.getWriter();
		
		//根据用户传送过来的id显示商品的详细信息
		String id = request.getParameter("id");
		Book book = (Book) Db.getAll().get(id);
		out.write(book.getId()+"
");
		out.write(book.getAuthor()+"
");
		out.write(book.getName()+"
");
		out.write(book.getDescription()+"
");
		
		//构建Cookie,回写给浏览器
		String cookieValue = buildCookie(id,request);
		Cookie cookie = new Cookie("bookHistory",cookieValue);
		cookie.setMaxAge(30*24*60*60);
		cookie.setPath("/CookieTest");
		response.addCookie(cookie);
	} 
	
	private String buildCookie(String id, HttpServletRequest request)
	{
		String bookHistory = null;
		Cookie[] cookies = request.getCookies();
		for(int i=0;cookies!=null && i list = new LinkedList(Arrays.asList(bookHistory.split("\\,")));
		if(list.contains(id))
		{
			list.remove(id);
		}
		else if(list.size()>=3)    //控制显示用户浏览过的商品最多为3个
		{			
			list.removeLast();
		}
		list.addFirst(id);
		
		StringBuffer sb = new StringBuffer();
		for(String bookId : list)
		{
			sb.append(bookId+",");
		}
				
		return sb.deleteCharAt(sb.length()-1).toString();
	}

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

两者在web.xml中的配置为：

  
  
    IndexInf
    CookieDemo.IndexInf
  
  
    ShowGoodsInf
    CookieDemo.ShowGoodsInf
  

  
    IndexInf
    /servlet/IndexInf
  
  
    ShowGoodsInf
    /servlet/ShowGoodsInf
  	
  
    index.jsp
  

运行结果：

当浏览主页时：

点击“Spring开发”后跳转页面至：

通过一系列浏览后，刷新主显示页面后看到：