Cookie-白红宇

阅读量：4681 次

发布时间：2019-06-09

本文共 7195 字，大约阅读时间需要 23 分钟。

利用cookie实现：记录上次访问时间

response.setCharacterEncoding("utf-8");        response.setContentType("text/html;charset=utf-8");        PrintWriter out = response.getWriter();        out.print("删除上次访问时间");        out.print("您上次的访问时间是:");        // 获得用户的访问时间cookie        Cookie cookies[] = request.getCookies();        for (int i = 0; cookies != null && i < cookies.length; i++) {            if (cookies[i].getName().equals("lastAccessTime")) {                long value = Long.parseLong(cookies[i].getValue());                Date date = new Date(value);                DateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");                out.write(format.format(date));            }        }        // 给用户回送最新的访问时间        Cookie cookie = new Cookie("lastAccessTime", System.currentTimeMillis()                + "");        cookie.setMaxAge(3600 * 24 * 365);// 设置保存时间是以秒为单位，这里是设置保存大约1年        cookie.setPath("ServletDemo");        response.addCookie(cookie);

删除Cookie

Cookie cookie = new Cookie("lastAccessTime",System.currentTimeMillis()+"");        cookie.setPath("ServletDemo");//原先cookie的存储路径一定要一致        cookie.setMaxAge(0);//设置Cookie存活时间为0，关闭浏览器后，session将会被清楚

response.addCookie(cookie); response.setCharacterEncoding("utf-8"); response.setContentType("text/html;charset=utf-8"); response.getWriter().write("删除cookie成功
返回");

模拟浏览商品的Servlet

/** * 模拟浏览商品 */@WebServlet("/cookieDemo3")public class CookieDemo3 extends HttpServlet {    private static final long serialVersionUID = 1L;    protected void doGet(HttpServletRequest request,            HttpServletResponse response) throws ServletException, IOException {        response.setCharacterEncoding("UTF-8");        response.setContentType("text/html;charset=utf-8");        PrintWriter out = response.getWriter();        out.write("本店有如下商品：
");        // 输出网站所有商品        Map
     
       map = DB.getAll();        for (Map.Entry
      
        entry : map.entrySet()) {            Book book = entry.getValue();            out.write("
       "                    + book.getName() + "
       
");        }        // 显示用户曾经浏览过的商品        out.write("
       
");        out.write("你曾经浏览过的商品：
       
");        Cookie cookie[] = request.getCookies();        for (int i = 0; cookie != null && i < cookie.length; i++) {            if (cookie[i].getName().equals("bookHistory")                    && cookie[i].getValue() != null) {                String ids[] = cookie[i].getValue().split("\\,");                for (String id : ids) {                    Book book = map.get(id);                    out.write("
       " + book.getName()                            + "
       
");                }            }        }    }    protected void doPost(HttpServletRequest request,            HttpServletResponse response) throws ServletException, IOException {        doGet(request, response);    }}//模拟数据库信息class DB {    private static Map
       
         map = new LinkedHashMap();    static {        map.put("1", new Book("1", "java", "1,java"));        map.put("2", new Book("2", "html", "1,html"));        map.put("3", new Book("3", "css", "1,css"));        map.put("4", new Book("4", "javascript", "1,javascript"));        map.put("5", new Book("5", "xml", "1,xml"));        map.put("6", new Book("6", "jsp", "1,jsp"));    }    public static Map getAll() {        return map;    }} class Book {        public Book() {    }  public Book(String id, String name, String description) {        super();        this.id = id;        this.name = name;        this.description = description;    }　　 private String id;    private String name;    private String 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 getDescription() {        return description;    }    public void setDescription(String description) {        this.description = description;    }}

模拟展示商品详细信息的Servlet

/* * 模拟展示商品详细信息的Servlet * */@WebServlet("/cookieDemo4")public class CookieDemo4 extends HttpServlet {    private static final long serialVersionUID = 1L;    protected void doGet(HttpServletRequest request,            HttpServletResponse response) throws ServletException, IOException {        response.setCharacterEncoding("utf-8");        response.setContentType("text/html;charset=utf-8");        PrintWriter out = response.getWriter();        String id = request.getParameter("id");        Book book = (Book) DB.getAll().get(id);        out.write(book.getName() + ":" + book.getDescription());        out.write("
返回");        // 构造Cookie 返回给浏览器        String cookValue = buildCookieValue(id, request);        Cookie cookie = new Cookie("bookHistory", cookValue);        cookie.setMaxAge(3600 * 24 * 30);// 设置cookie保存时间为一个月        cookie.setPath("ServletDemo");        response.addCookie(cookie);    }    // 构造CookieValue    private String buildCookieValue(String id, HttpServletRequest request) {        /*         * 分析Cookie中可能存在的bookHistory          *          已存在值        将要插入值 　　　　　*　   bookHistory=null        1              情况1          *    bookHistory=2,3,1       1              情况2         *    bookHistory=2,4,5       1              情况3          *    bookHistory=2,3         1              情况4         */        String bookHistory = null;        Cookie cookie[] = request.getCookies();        for (int i = 0; cookie != null && i < cookie.length; i++) {            if (cookie[i].getName().equals("bookHistory")) {                bookHistory = cookie[i].getValue();                                if (bookHistory == null) { //情况1                    return id;                }                LinkedList list = new LinkedList(Arrays.asList(bookHistory.split("\\,")));　　　　　　　　　//简化代码后                if (list.contains(id)) {  //情况2                    list.remove(id);                } else {                    if (list.size() >= 3) { //情况3                        list.removeLast();                    }                } 　　　　　　　　　//情况4                list.addFirst(id);                                StringBuffer sb = new StringBuffer();                for (Object ids : list) {                    sb.append(ids.toString() + ",");                }                return sb.deleteCharAt(sb.length() - 1).toString();                // 简化代码前                /*                 *  if (list.contains(id)) { // bookHistory=2,3,1 1                 *      list.remove(id);                  *      list.addFirst(id);                  *   } else {
                     *      if (list.size()>= 4) {// bookHistory=2,4,5 1                  *          list.removeLast();                 *          list.addFirst(id);                  *     } else { // bookHistory= 2,3 1                 *       list.addFirst(id);                  *       } 　　　　　　　　　　*　　}                 */            }        }        return null;    }    protected void doPost(HttpServletRequest request,            HttpServletResponse response) throws ServletException, IOException {        doGet(request, response);    }}

转载于:https://www.cnblogs.com/lhy_2011/p/4044819.html

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