在千锋“逆战”学习第56天
每日一句：成功很少是由创意的质量决定的，但它时常由你执行的质量来决定。
今天学习了Cookie和Session的知识。
明天继续努力。
Cookie案例 记录上一次访问时间
@WebServlet(name = "Demo05Servlet", urlPatterns = "/demo05")
public class Demo05Servlet extends HttpServlet {
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
Cookie[] cookies = req.getCookies();
Cookie cookie = null;
if (cookies != null && cookies.length != 0) {
for (Cookie sonCookie : cookies) {
if ("lastTime".equals(sonCookie.getName())) {
cookie = sonCookie;
}
}
}
SimpleDateFormat format = new SimpleDateFormat("yyyy年MM月dd日 hh:mm:ss");
if (null==cookie) {
Date currentDate = new Date();
System.out.println("第一次访问，时间为：" + format.format(currentDate));
cookie = new Cookie("lastTime", currentDate.getTime() + "");
} else {
// System.out.println(cookie.getValue());
long lastTimeMills = Long.parseLong(cookie.getValue());
Date lastDate = new Date(lastTimeMills);
String lastTimeStr = format.format(lastDate);
System.out.println("上一次访问，时间为：" + lastTimeStr);
Date currentDate = new Date();
// cookie.setValue(currentDate.getTime() + " ");
cookie = new Cookie("lastTime",currentDate.getTime()+"");
}
resp.addCookie(cookie);
}
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req, resp);
}
}
Cookie案例 商品浏览记录
- books.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>商品页面</title>
</head>
<body>
<h2>商品目录</h2>
<a href="history?id=0">西游记</a><br>
<a href="history?id=1">红楼梦</a><br>
<a href="history?id=2">水浒传</a><br>
<a href="history?id=3">三国志</a>
</body>
</html>
- HistoryServlet
@WebServlet(name = "HistoryServlet", urlPatterns = "/history")
public class HistoryServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String id = request.getParameter("id");
Cookie cookie = null;
Cookie[] cookies = request.getCookies();
if (cookies != null && cookies.length != 0) {
for (Cookie sonCookie : cookies) {
if ("history".equals(sonCookie.getName())) {
cookie = sonCookie;
}
}
}
if (cookie == null) {
cookie = new Cookie("history", id);
} else {
String historyStr = cookie.getValue();
if (!historyStr.contains(id)) {
historyStr += "-" + id;
cookie.setValue(historyStr);
} else {
}
}
response.addCookie(cookie);
response.sendRedirect(request.getContextPath() + File.separator + "show");
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
}
}
- ShowHistoryServlet
@WebServlet(name = "ShowHistoryServlet", urlPatterns = "/show")
public class ShowHistoryServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
Cookie cookie = null;
Cookie[] cookies = request.getCookies();
if (cookies != null && cookies.length != 0) {
for (Cookie sonCookie : cookies) {
if ("history".equals(sonCookie.getName())) {
cookie = sonCookie;
}
}
}
StringBuffer responseContent = new StringBuffer();
if (cookie == null) {
responseContent.append("<font color = 'red'>没有浏览记录</font>");
responseContent.append("<a href = 'books.html'>浏览商品</a>");
} else {
String[] bookNames = {"西游记", "红楼梦", "水浒传", "三国志"};
String historyStr = cookie.getValue();
String[] historys = historyStr.split("-");
responseContent.append("浏览记录如下<br>");
for (String history : historys) {
String bookName = bookNames[Integer.parseInt(history)];
responseContent.append(bookName + "<br>");
}
}
response.setContentType("text/html;charset=utf-8");
response.getWriter().write(responseContent.toString());
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
}
}
