使用cookie法，查看最近看过的书，cookie法,<无详细内容>``` j

使用cookie法，查看最近看过的书，cookie法,<无详细内容>``` j

<无详细内容>``` java

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;}

}

`````` java

import java.util.LinkedHashMap;import java.util.Map;

import cn.huiyu.ben.Book;

public class BookDao { private static Map<String,Book> bookMap = new LinkedHashMap<String, Book>(); 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<String,Book> getBooks(){    return bookMap;}public static Book getBook(String id){    return bookMap.get(id);}

}

`````` javapublic 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<String,Book> map = BookDao.getBooks(); for(Map.Entry<String , Book> entry : map.entrySet()){ Book book = entry.getValue(); response.getWriter().write("<a href='"+request.getContextPath()+"/servlet/BookInfoServlet?id="+book.getId()+"'>"+book.getName()+"</a><br>"); } response.getWriter().write("<hr>");

    //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:<br>");        String[] ids = findC.getValue().split(",");        for(String id : ids){            Book book = BookDao.getBook(id);            response.getWriter().write(book.getName()+"<br>");        }    }}

`````` javapublic 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("<h1>书名:"+book.getName()+"</h1>"); response.getWriter().write("<h3>作者:"+book.getAuth()+"</h3>"); response.getWriter().write("<h3>售价:"+book.getPrice()+"</h3>"); response.getWriter().write("<h3>出版社:"+book.getPublish()+"</h3>"); response.getWriter().write("<h3>描述信息:"+book.getDescription()+"</h3>"); }

    //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<olds.length &amp;&amp; buffer.toString().split(",").length<3 ;i++){            String old = olds[i];            if(!old.equals(book.getId())){                buffer.append(old+",");            }        }        ids = buffer.substring(0, buffer.length()-1);    }    Cookie lastC = new Cookie("last",ids);    lastC.setMaxAge(3600*24*30);    lastC.setPath(request.getContextPath());    response.addCookie(lastC);}

```