public class CookiesServlet2 extends HttpServlet {
// 显示商品详细信息
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();
// 根据用户带过来的id，显示相应商品的详细信息
String id = request.getParameter("id");
Book book = (Book) Db.getAll().get(id);
out.write(book.getId() + "<br/>");
out.write(book.getName() + "<br/>");
out.write(book.getAuthor() + "<br/>");
out.write(book.getDescription() + "<br/>");
// 构建Cooikes回写给浏览器
String cookieValue = buildCookie(id, request);
Cookie cookie = new Cookie("bookHistory", cookieValue);
cookie.setMaxAge(1 * 30 * 24 * 60 * 60);
cookie.setPath("/NANA");
response.addCookie(cookie);
}
private String buildCookie(String id, HttpServletRequest request) {
// if none cookie, bookHistory=null, cookie value =1
// if contain cookie,bookHistory=2,5,1 return 1 2 5
// cookieHistory=2,5,4 browns 1 return 1,2,5 到了列表最大值
// cookieHistory=2,5 browns 1 return 1,2,5 没到最大值
String bookHistory = null;
Cookie cookies[] = request.getCookies();
for (int i = 0; cookies != null && i < cookies.length; i++) {
if (cookies[i].getName().equals("bookHistory")) {
bookHistory = cookies[i].getValue();
}
}
if (bookHistory == null) {
return id;
}
LinkedList<String> list = new LinkedList<String>(
Arrays.asList(bookHistory.split("\\,")));
if (list.contains(id)) {
list.remove(id);
list.addFirst(id);
} else {
if (list.size() >= 3) {
list.removeLast();
list.addFirst(id);
} else {
list.addFirst(id);
}
}
StringBuffer sb = new StringBuffer();
for(String bid:list){
sb.append(bid+",");
}
return sb.deleteCharAt(sb.length()-1).toString();
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}