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一、Cookie

（1）Cookie 基本使用

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發(fā)送 cookie

package com.test.web;

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;

// 發(fā)送cookie demo
@WebServlet("/servletSetCookie")
public class ServletSetCookie extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp){
        // 創(chuàng)建cookie對(duì)象
        Cookie cookie = new Cookie("myCookie", "123123");
        // 發(fā)送cookie
        resp.addCookie(cookie);
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp){
        this.doGet(req, resp);
    }
}

獲取cookie

package com.test.web;

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;

// 獲取 cookie demo
@WebServlet("/servletGetCookie")
public class ServletGetCookie extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp){
        Cookie[] cookies = req.getCookies();
        for (Cookie cookie : cookies) {

            String name = cookie.getName();
            if (name.equals("myCookie")) {
                System.out.println("成功獲取到之前設(shè)置的cookie " + name + ":" + cookie.getValue());
                break;
            }
        }
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp){
        this.doGet(req, resp);
    }
}

（2）Cookie 原理

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設(shè)置cookie：后端服務(wù)通過 set-cookie:username=zs 響應(yīng)頭來告知瀏覽器創(chuàng)建一個(gè)名為username，值為zs的 cookie
獲取cookie：后端服務(wù)接收這次請(qǐng)求時(shí)，在請(qǐng)求頭 cookie 里面獲取的所有cookie

（3）Cookie 細(xì)節(jié)

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二、Session

（1）Session 基本使用

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存儲(chǔ) Session

package com.test.web.session;

import javax.servlet.annotation.WebServlet;
import javax.servlet.http.*;

@WebServlet("/servletSetSession")
public class ServletSetSession extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp){
        // 獲取session對(duì)象
        HttpSession session = req.getSession();
        // 設(shè)置session
        session.setAttribute("username", "張三");
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp){
        this.doGet(req, resp);
    }
}

獲取 Session

package com.test.web.session;

import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

@WebServlet("/servletGetSession")
public class ServletGetSession extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp){
        // 獲取session對(duì)象
        HttpSession session = req.getSession();
        Object username = session.getAttribute("username");
        System.out.println("成功獲取存儲(chǔ)的 username:" + username);
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp){
        this.doGet(req, resp);
    }
}

（2）Session 原理

Session 是基于Cookie實(shí)現(xiàn)的，服務(wù)器會(huì)給客戶端存儲(chǔ)一個(gè) sessionid 的 cookie，瀏覽器每次請(qǐng)求的時(shí)候會(huì)自動(dòng)帶上這個(gè) sessionid 用于區(qū)分。

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（3）Session 細(xì)節(jié)

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三、Cookie和Session的區(qū)別

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參考：黑馬java教程