Cookie的使用

常用方法

 

Cookie(String name, String value) ：创建 cookie 对象

String getName() ： 获取 cookie 的名称

String getValue() : 获取 cookie 的值

void setPath(String uri) ： 设置 cookie 的路径 —— 浏览器根据这个路径判断哪些

cookie 要发送给服务器

void addCookie(Cookie cookie) ：将 cookie 发送给浏览器

Cookie[] getCookies() ：获取浏览器发送的 cookie

void setMaxAge(int expiry) ：设置 cookie 的最大生存时间（单位：秒） , 超过了该时

间后 Cookie 会自动销毁 , 当时间为 0 的时候 , 意思为立即删除此 Cookie

 代码

package org.example;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebServlet("/cookie2")
public class CookieServlet2 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req,resp);
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //创建cookie
        final Cookie cookie1 = new Cookie("user", "tom");
        //将cookie1发送给浏览器
        resp.addCookie(cookie1);
        final Cookie[] cookies = req.getCookies();
        if(cookies!=null){
            for (Cookie cookie : cookies) {
                System.out.println(cookie.getName()+"---"+cookie.getValue());
            }
        }
    }
}

运行以上代码，需要配置Tomcat,配置相关依赖

---

代码 

package org.example;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
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;

@WebServlet("/cookie3")
public class CookieServlet3 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req,resp);
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //获取用户当前访问时间
        final Date date = new Date();
        final SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd/hh:mm:ss");
        final String format1 = format.format(date);
        System.out.println(format1);
        //将数据存入cookie
        final Cookie cookie = new Cookie("time", format1);
        cookie.setMaxAge(60*60);
        //将数据发送给浏览器
        resp.addCookie(cookie);
        //第二次访问
        final Cookie[] cookies = req.getCookies();
        if(cookies !=null){
            for (Cookie cookie1 : cookies) {
                if("time".equals(cookie1.getName())){
                    resp.getWriter().write(cookie1.getValue());
                }
            }
        }
    }
}

访问该地址两次，第二次显示上次访问时间