Cookie_细节

一次可以发生多个cookie

java代码

CookieDemo03类

package com.bai.Cookie;

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("/CookieDemo03")
public class CookieDemo03 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //创建Cookie对象
        Cookie c1 = new Cookie("msg1", "hello");
        Cookie c2 = new Cookie("msg2", "hello cookie");
        //发送Cookie
        resp.addCookie(c1);
        resp.addCookie(c2);
    }

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

CookieDemo02类

package com.bai.Cookie;

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("/CookieDemo02")
public class CookieDemo02 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //创建Cookie对象
        Cookie[] cookies = req.getCookies();
       if (cookies!=null){
           for (Cookie cookie : cookies) {
               String name = cookie.getName();
               String value = cookie.getValue();
               System.out.println(name+":"+value);
           }
       }
    }

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

运行结果

可以创建多个Cookie对象使用response调用多次addCookie方法发生cookie即可

Cookie存活周期

默认情况下，当浏览器关闭后 cookie数据被销毁
持久化存储：
- setMaxAge(int seconds)
1. 正数：将Cookie数据写到硬盘的文件中持久化存储 cookie存活时间
2. 负数：默认值
3. 零：删除cookie信息

默认输出结果

关闭CookieDemo01的结果

自定义存活方式

java代码

package com.bai.Cookie;

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("/CookieDemo04")
public class CookieDemo04 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //创建Cookie对象
        Cookie c1 = new Cookie("msg1", "setMaxAge");
        //设置cookie的存活时间
        c1.setMaxAge(30);//将cookie持久化到硬盘 30秒后会自动删除cookie文件
        //发送Cookie
        resp.addCookie(c1);
    }

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

运行结果

关闭浏览器

Cookie存储中文

在tomcat 8 之前 cookie中不能直接存储中文数据
在tomcat 8 之后 cookie支持中文数据

java代码

package com.bai.Cookie;

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("/CookieDemo05")
public class CookieDemo05 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //创建Cookie对象
        Cookie c1 = new Cookie("msg", "张三");
        //发送Cookie
        resp.addCookie(c1);
    }

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