import java.io.Serializable; public class Book implements Serializable { private String id; private String name; private String price; private String auth; private String publish; private String description; public Book() { } public Book(String id, String name, String price, String auth, String publish, String description) { super(); this.id = id; this.name = name; this.price = price; this.auth = auth; this.publish = publish; this.description = description; } public String getDescription() { return description; } public void setDescription(String description) { 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 getPrice() { return price; } public void setPrice(String price) { this.price = price; } public String getAuth() { return auth; } public void setAuth(String auth) { this.auth = auth; } public String getPublish() { return publish; } public void setPublish(String publish) { this.publish = publish; } } 

 import java.util.LinkedHashMap; import java.util.Map; import cn.huiyu.ben.Book; public class BookDao { private static Map bookMap = new LinkedHashMap(); private BookDao() { } static{ bookMap.put("1", new Book("1","1111","11.0","zqwang","111出版社","111111111")); bookMap.put("2", new Book("2","2222","22.0","zqwang","222出版社","222222222")); bookMap.put("3", new Book("3","3333","33.0","zqwang","333出版社","333333333")); } public static Map getBooks(){ return bookMap; } public static Book getBook(String id){ return bookMap.get(id); } } 

 public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=utf-8"); //1.查询数据库中所有的书展示 Map map = BookDao.getBooks(); for(Map.Entry entry : map.entrySet()){ Book book = entry.getValue(); response.getWriter().write(""+book.getName()+"
"); } response.getWriter().write("
"); //2.显示之前看过的书 Cookie [] cs = request.getCookies(); Cookie findC = null; if(cs!=null){ for(Cookie c : cs){ if("last".equals(c.getName())){ findC = c; } } } if(findC == null){ response.getWriter().write("没有看过任何书!"); }else{ response.getWriter().write("您曾经浏览过的书:
"); String[] ids = findC.getValue().split(","); for(String id : ids){ Book book = BookDao.getBook(id); response.getWriter().write(book.getName()+"
"); } } } 

 public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=utf-8"); //1.获取要看的书的id,查询数据库找出书,输出书的详细信息 String id = request.getParameter("id"); Book book = BookDao.getBook(id); if(book==null){ response.getWriter().write("找不到这本书!"); return; }else{ response.getWriter().write("
书名:"+book.getName()+"
"); response.getWriter().write("
作者:"+book.getAuth()+"
"); response.getWriter().write("
售价:"+book.getPrice()+"
"); response.getWriter().write("
出版社:"+book.getPublish()+"
"); response.getWriter().write("
描述信息:"+book.getDescription()+"
"); } //2.发送cookie保存最后看过的书 // --- 1 --> 1 // 1 --2,1 --> 2,1 // 2,1--3,2,1 --> 3,2,1 // 3,2,1 -- 4,3,2 --> 4,3,2 // 4,3,2 --3,4,2 --> 3,4,2 String ids = ""; Cookie [] cs = request.getCookies(); Cookie findC = null; if(cs!=null){ for(Cookie c : cs){ if("last".equals(c.getName())){ findC = c; } } } if(findC == null){ //说明之前没有看过书的记录 ids += book.getId(); }else{ //说明之前有历史看过的书的记录,需要根据历史记录算一个新的记录出来 String [] olds = findC.getValue().split(","); StringBuffer buffer = new StringBuffer(); buffer.append(book.getId()+","); for(int i = 0;i