《JavaWeb---利用cookie记录用户的历史浏览》

代码虽少，却遇到了很多问题。感觉也学到了很多东西。

//展示商品，“首页”Servlet
package com.fenghuo.cookie;

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 BuyServlet extends HttpServlet {

	/**
	 *  Title：利用cookie技术记录客户的历史浏览
	 *  Copyright: Copyright (c) 2012
	 *  @author: 烽火
	 *  @version 1.0 2012-09-14
	 */
	private static final long serialVersionUID = 4408943836189873374L;

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		
		//解决乱码问题
		response.setCharacterEncoding("UTF-8");
		response.setContentType("text/html;charset=UTF-8");
		PrintWriter out = response.getWriter();
	
		out.print("我们店有如下商品：(点击查看详情)
");
		
		//得到”数据库“数据
		Map map = DB.getAll();
		
		//展示商品，将商品id通过链接带给ShowObject
		out.print("=========================
");
		for (int i = 1; i < map.size()+1; i++){
			out.print(""+map.get(i+"").getName()+"
");
		}
		
		//显示曾经浏览的商品
		out.print("您曾经浏览过的商品：
");
		
		//得到用户带来的cookie值，返回值是cookie数组
		Cookie[] cookies = request.getCookies();
		for (int i = 0; cookies != null && i < cookies.length; i++){
			
			//找到我们想要的cookie
			if (cookies[i].getName().equals("historyCookie")){
				String[] ids = cookies[i].getValue().split("\\,");
				
				//得到cookie中存在的id，展现浏览过的商品
				for (String id : ids){
					out.print(""+map.get(id).getName()+"
");
				}
			}
		}
	}

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

		doGet(request, response);
	}
}

//自定义数据
class DB{
	private static LinkedHashMap map = new LinkedHashMap();
	static{
		map.put("1", new MyObject("1", "杯子", "12.0", "烽火牌杯子就是好！"));
		map.put("2", new MyObject("2", "毛巾", "5.0", "吸水性刚刚的！"));
		map.put("3", new MyObject("3", "脸盆", "8.0", "容积大，可放衣物多！"));
		map.put("4", new MyObject("4", "肥皂", "6.0", "强劲去污能力强！"));
		map.put("5", new MyObject("5", "暖瓶", "18.0", "不保温退货！"));
	}
	
	public static Map getAll(){
		return map;
	}
}
class MyObject{
	
	private String id;
	private String name;
	private String price;
	private String describe;
	
	public MyObject(String id, String name, String price, String describe) {
		super();
		this.id = id;
		this.name = name;
		this.price = price;
		this.describe = describe;
	}
	
	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 getPrice() {
		return price;
	}
	public void setPrice(String price) {
		this.price = price;
	}
	public String getDescribe() {
		return describe;
	}
	public void setDescribe(String describe) {
		this.describe = describe;
	}
}

//显示用户的详细信息的Servlet
package com.fenghuo.cookie;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.LinkedList;
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 ShowObject extends HttpServlet {

	/**
	 *  Title：输出客户要看的商品，同时回写cookie
	 *  Copyright: Copyright (c) 2012
	 *  @author: 烽火
	 *  @version 1.0 2012-09-14
	 */
	private static final long serialVersionUID = 2894544204585860934L;

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		
		//解决乱码问题
		response.setCharacterEncoding("UTF-8");
		response.setContentType("text/html;charset=UTF-8");
		PrintWriter out = response.getWriter();
		
		//得到Url中的id
		String id = request.getParameter("id");
		
		//获取”数据库“中数据
		Map map = DB.getAll();
		//根据id得到浏览的商品
		MyObject myobj = (MyObject) map.get(id);
		
		out.write("你要看的商品是："+myobj.getName()+"
");
		out.write("价格："+myobj.getPrice()+"
");
		out.write("对该商品的描述是：
");
		out.write(myobj.getDescribe());
		
		//给浏览器回写cookie
		String cookieValue = buildCookie(id, request);//产生想要的cookie中的值
		Cookie cookie = new Cookie("historyCookie", cookieValue);
		cookie.setMaxAge(1*24*3600);
		cookie.setPath("/myweb");
		response.addCookie(cookie);
	}

	private String buildCookie(String id, HttpServletRequest request) {
		
		String historyCookie = null;
		
		//得到请求中带来的cookie值
		Cookie[] cookies = request.getCookies();
		for (int i = 0; cookies != null && i < cookies.length; i++){
			if (cookies[i].getName().equals("historyCookie") ){
				historyCookie = cookies[i].getValue();
			}
		}
		
		//如果为空返回当前商品的id
		if (historyCookie == null){
			return id;
		}
		
		LinkedList list = new LinkedList( Arrays.asList((historyCookie.split("\\,"))));
		
		//对不同的情况进行分析返回id的值
		if (list.contains(id)){
			list.remove(id);
		}else{
			if (list.size() >= 5){
				list.removeLast();
			}
		}
		list.addFirst(id);
		
		StringBuffer sb = new StringBuffer();
		for (String sid : list){
			sb.append(sid + ",");
		}
		sb.deleteCharAt(sb.length()-1);
		
		return sb.toString();
	}

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

		doGet(request, response);
	}
}

第一次浏览商品产生cookie

刷新显示历史浏览

浏览下一商品

刷新显示

再浏览第一次浏览的商品刷新移到前面

浏览多个商品