JavaWeb篇——Cookie讲解

Cookie讲解

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1. 从请求中拿到cookie信息
2. 服务器响应给客户端cookie

public class CookieDemo01 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("UTF-8");
        resp.setCharacterEncoding("UTF-8");

        PrintWriter out = resp.getWriter();
        //Cookie,服务器从客户端获取
        Cookie[] cookies = req.getCookies();//获取cookie
        //判断cookie是否为空
        if (cookies!=null){
            out.write("您上次访问的时间是：");
            for(int i=0;i<cookies.length;i++){
                Cookie cookie = cookies[i];
                if (cookie.getName().equals("loginTime")){//获取cookie的key与设置的cookie的key进行比较
                    long loginTime = Long.parseLong(cookie.getValue());//获得cookie的value值
                    Date date = new Date(loginTime);
                    out.write(date.toLocaleString());
                }
            }
        }else{
            out.write("这是您第一次访问本站");
        }
        Cookie cookie = new Cookie("loginTime",System.currentTimeMillis()+"");//新建一个cookie值
        cookie.setMaxAge(24*60*60);//设置cookie的有效期（24小时）
        resp.addCookie(cookie);//响应给客户端的cookie
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}