Cookies应用之上一次访问时间

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
public class LastTimeServlet extends HttpServlet {
    private Cookie cookie;

    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setContentType("text/html;charset=utf-8");
        //第一次访问
        Cookie[] cookies = req.getCookies();
        if (cookies != null && cookies.length > 0) {
            for (Cookie cookie : cookies) {
                if (cookie.getName().equals("lastTime")) {
                    Cookie cookieNew = new Cookie("lastTime", System.currentTimeMillis() + "");
                    cookieNew.setMaxAge(60 * 60);
                    resp.addCookie(cookieNew);
                    resp.getWriter().print("上次访问时间" + getFormatDateString(Long.valueOf(cookie.getValue())));
                }
            }
        } else {
            long mills = System.currentTimeMillis();
            cookie = new Cookie("lastTime", String.valueOf(mills));
            cookie.setMaxAge(60 * 60);
            resp.addCookie(cookie);//给响应数据包(响应头  SetCookie: xxx)设置数据
            resp.getWriter().write("第一次访问: 访问时间为 " + getFormatDateString(mills));
        }
    }

    /**
     * 把时间戳格式化为自定义的格式
     *
     * @param mills
     * @return
     */
    private String getFormatDateString(long mills) {
        Date date = new Date(mills);
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        return sdf.format(date);
    }
}