JavaWeb Cookie

public class CookieDemo extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1.创建cookie对象
        Cookie c = new Cookie("msg","hello");
        //2.发送cookie
        resp.addCookie(c);
    }
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
       this.doPost(req, resp);
    }
}

public class CookieDemo2 extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //3.获取Cookie对象
        Cookie[] cookies = req.getCookies();
        //获取数据，遍历Cookie
        if (cookies != null){
            for (Cookie cookie : cookies) {
                String name = cookie.getName();
                String value = cookie.getValue();
                System.out.println(name+value);
            }
        }
    }
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
       this.doPost(req, resp);
    }
}

public class CookieDemo3 extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1.创建多cookie对象
        Cookie c1 = new Cookie("msg","hello");
        Cookie c2 = new Cookie("name","zhangsan");
        //2.发送多个cookie
        resp.addCookie(c1);
        resp.addCookie(c2);
    }
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
       this.doPost(req, resp);
    }
}

public class CookieDemo4 extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1.创建cookie对象
        Cookie c1 = new Cookie("msg","setMaxAge");
        //2.设置Cookie的存活时间
        c1.setMaxAge(30);//将cookie持久化到硬盘30秒，30秒后会自动删除文件
        //3.发送cookie
        resp.addCookie(c1);
    }
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
       this.doPost(req, resp);
    }
}

public class CookieDemo5 extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1.创建cookie对象
        Cookie c1 = new Cookie("msg","setMaxAge");
        //2.设置Cookie的存活时间
        c1.setMaxAge(30);//将cookie持久化到硬盘30秒，30秒后会自动删除文件
        //3.设置cookie的共享范围
        c1.setPath("/"); //根路径("/")，项目("/project")
        //4.不同的服务器之间共享问题
        c1.setDomain(".baidu.com"); //如果设置一级域名相同，那么多个服务器之间cookie可以共享
        //setDomain(".baidu.com"),那么tieba.baidu.com和news.baidu.com中cookie可以共享
        //3.发送cookie
        resp.addCookie(c1);
    }
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
       this.doPost(req, resp);
    }
}



/**
 * 在服务器中的Servlet判断是否有一个名为lastTime的cookie
 * 1.有：不是第一次访问
 * -响应数据：欢迎回来，您上次访问时间为:***
 * -写回Cookie: lastTime=*****
 * 2.没有，是第一次访问
 * -响应数据：您好欢迎您首次访问
 * -写回Cookie:lastTime=****
 */
public class cookieTest extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //设置响应的的数据格式编码
        resp.setContentType("text/html;charset=utf-8");
        //1.获取所有Cookie判断名称是否为lastTime
        Cookie[] cookies = req.getCookies();
        boolean flag = false;
        //2.遍历Cookie数组
        if (cookies != null && cookies.length > 0) {
            for (Cookie cookie : cookies) {
                //3.获取cookie名称
                String name = cookie.getName();
                //4.判断名称是否是lastTime
                if ("lastTime".equals(name)) {
                    flag = true;
                    //5.有该cookie则不是第一次访问
                    //6.设置响应数据，设置cookie 的value
                    Date date = new Date();
                    SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日 HH:mm:ss");
                    String str_date = sdf.format(date);
                    //URL编码去掉空格
                    str_date = URLEncoder.encode(str_date, "utf-8");
                    cookie.setValue(str_date);
                    //设置cookie存活期为一个月
                    cookie.setMaxAge(60 * 60 * 24 * 30);
                    //获取当前时间字符串后，重新发送cookie
                    String value = cookie.getValue();
                    //URL解码
                    value = URLDecoder.decode(value,"utf-8");
                    resp.getWriter().write("<h1>欢迎回来,您上次访问的时间为:" + value + "</h1>");
                    resp.addCookie(cookie);
                }
            }
        }
        if (cookies == null || cookies.length == 0 || !flag) {
            //如果没有cookie那么这是第一次访问
            //1.响应数据，设置cookie的value
            Date date = new Date();
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日 HH:mm:ss");
            String str_date = sdf.format(date);
            //URL编码去掉空格
            str_date = URLEncoder.encode(str_date, "utf-8");
            //新建Cookie将k,v传入
            Cookie cookie = new Cookie("lastTime", str_date);
            //设置cookie存活时间为一个月
            cookie.setMaxAge(60 * 60 * 24 * 30);
            //获取字符串，重新发送cookie
            resp.addCookie(cookie);
            //获取当前时间字符串后，重新发送cookie
            String value = cookie.getValue();
            //URL解码
            value = URLDecoder.decode(value,"utf-8");
            resp.getWriter().write("<h1>您好，欢迎您首次访问</h1>");
        }
    }
}