package de.bvb.cookie;

import java.io.IOException;

import java.io.PrintWriter;

import java.util.Date;

import java.util.LinkedHashMap;

import java.util.Map;

import java.util.Map.Entry;

import javax.servlet.ServletException;

import javax.servlet.http.Cookie;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

/**

 * 显示商品列表和已经浏览过的商品

 *

 * @author joker

 *

 */

public class CookieDemo11 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        response.setCharacterEncoding("UTF-8");

        response.setContentType("text/html; charset=UTF-8");

        PrintWriter out = response.getWriter();

        // 显示商品列表

        out.write("商品列表: <br/>");

        for (Entry<String, Book> b : Db.getBooks().entrySet()) {

            out.write("<a target='_blank' href='/web/CookieDemo12?id="

                    + b.getKey() + "'>" + b.getValue().getName() + "</a><br/>");

        }

        // 显示浏览过的商品

        out.write(" <br/> <br/>浏览过的商品: <br/>");

        Cookie[] cookies = request.getCookies();

        for (int i = 0; cookies != null && i < cookies.length; i++) {

            if (cookies[i].getName().equals("history")) {

                String[] ids = cookies[i].getValue().split("\\,");

                for (String s : ids) {

                    out.write(Db.getBooks().get(s).getName() + "<br/>");

                }

            }

        }

    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        doGet(request, response);

    }

}

class Db {

    private static LinkedHashMap<String, Book> books = new LinkedHashMap<String, Book>();

    static {

        books.put("1", new Book("1", "javaWeb", "javaweb"));

        books.put("2", new Book("2", "android", "android"));

        books.put("3", new Book("3", "spring", "spring"));

        books.put("4", new Book("4", "strus", "strus"));

        books.put("5", new Book("5", "ios", "ios"));

    }

    public static Map<String, Book> getBooks() {

        return books;

    }

}

class Book {

    private String id;

    private String name;

    private String description;

    public Book(String id, String name, String description) {

        super();

        this.id = id;

        this.name = name;

        this.description = description;

    }

    public Book() {

        super();

    }

    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 getDescription() {

        return description;

    }

    public void setDescription(String description) {

        this.description = description;

    }

}

package de.bvb.cookie;

import java.io.IOException;

import java.io.PrintWriter;

import java.util.Arrays;

import java.util.Date;

import java.util.LinkedList;

import java.util.Map.Entry;

import javax.enterprise.inject.ResolutionException;

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 javax.swing.text.DateFormatter;

/**

 * 显示商品详情

 *

 * @author joker

 *

 */

public class CookieDemo12 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        response.setCharacterEncoding("UTF-8");

        response.setContentType("text/html; charset=UTF-8");

        PrintWriter out = response.getWriter();

        // 显示商品详情

        out.write("商品详情: <br/>");

        String id = request.getParameter("id");

        for (Entry<String, Book> b : Db.getBooks().entrySet()) {

            if (id.equals(b.getKey())) {

                out.write(b.getValue().getId() + "<br/>");

                out.write(b.getValue().getName() + "<br/>");

                out.write(b.getValue().getDescription() + "<br/>");

            }

        }

        // 回写cookie，保存最后浏览的商品id

        String history = buildIds(id, request);

        Cookie cookie = new Cookie("history", history);

        cookie.setMaxAge(1 * 30 * 24 * 60 * 60);

        cookie.setPath("/web");

        response.addCookie(cookie);

    }

    private String buildIds(String id, HttpServletRequest request) {

        String history = null;

        Cookie[] cookies = request.getCookies();

        for (int i = 0; cookies != null && i < cookies.length; i++) {

            if (cookies[i].getName().equals("history")) {

                history = cookies[i].getValue();

            }

        }

        if (history == null) {

            return id;

        }

        LinkedList<String> ids = new LinkedList<String>(Arrays.asList(history

                .split("\\,")));

        if (ids.contains(id)) {

            ids.remove(id);

        } else {

            if (ids.size() >= 3) { // 最多显示3条浏览历史

                ids.removeLast();

            }

        }

        ids.addFirst(id);

        StringBuffer sb = new StringBuffer();

        for (String s : ids) {

            sb.append(s).append(",");

        }

        return sb.deleteCharAt(sb.length() - 1).toString();

    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        doGet(request, response);

    }

}