教你使用cookie法，查看最近看过的书

教你使用cookie法，查看最近看过的书 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; }

} 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("<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 && 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(36002430); lastC.setPath(request.getContextPath()); response.addCookie(lastC); }