Cookie 属性 和 构造

Cookie的添加 和 获取

记录最后访问时间

@WebServlet(name = "ServletDemo25", value = "/ServletDemo25")
public class ServletDemo25 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter pw = response.getWriter();
        pw.write("欢迎访问本网站，您的最后访问时间为：<br>");

        //创建Cookie对象，记录最后访问时间
        Cookie cookie = new Cookie("time", System.currentTimeMillis() + "");

        //设置最大存活时间 1h
        cookie.setMaxAge(3600);

        //将cookie对象添加到客户端
        response.addCookie(cookie);

        //获取cookie
        Cookie[] arr = request.getCookies();
        for (Cookie c : arr){
            if ("time".equals(c.getName())){
                //获取cookie对象中的value，进行写出
                String value = c.getValue();
                SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
                pw.write(sdf.format(new Date(Long.parseLong(value))));
            }
        }
    }

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

Cookie 使用细节

HttpSession

HttpSession实现类对象获取

@WebServlet(name = "ServletDemo26", value = "/ServletDemo26")
public class ServletDemo26 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获取参数值
        String username = request.getParameter("username");
        //获取session对象
        HttpSession session = request.getSession();
        System.out.println(session);
        System.out.println(session.getId());
        //设置参数到session中
        session.setAttribute("username",username);
    }

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

@WebServlet(name = "ServletDemo27", value = "/ServletDemo27")
public class ServletDemo27 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获取session对象
        HttpSession session = request.getSession();
        System.out.println(session);
        System.out.println(session.getId());
        //获取共享数据
        Object username = session.getAttribute("username");
        //响应
        response.getWriter().write(username + "");
    }

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

cookie禁用

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获取参数值
        String username = request.getParameter("username");
        //获取session对象
        HttpSession se1 = request.getSession(false);
        HttpSession session = request.getSession();
        System.out.println(session);
        System.out.println(session.getId());
        //设置参数到session中
        session.setAttribute("username",username);

        if (session != se1){
            response.setContentType("text/heml;charset=UTF-8");
            response.getWriter().write("为了不影响正常使用，请不要禁用浏览器的Cookie");
        }
    }

//实现url重写 相当于在地址栏后面拼接了jsessionid
response.getWriter().write("<a href='" + response.encodeURL("http://localhost/8080/session/servletDemo") + "'></a>");