一次会话多次请求——京东——手机——华为nove5

目的是多次请求间共享数据——手机——加入购物车——对刚刚加入购物车的手机进行支付

验证码也是多次请求

Cookie基本使用（客户端会话跟踪技术）

一次会话中，每次请求都携带Cookie数据进行访问

//cookie-Servlet-A.javapackage com.itheima.web.cookie;import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;
import java.net.URLEncoder;@WebServlet("/aServlet")
public class AServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//发送Cookie//1. 创建Cookie对象
//        Cookie cookie = new Cookie("username","zs");String value = "张三";//URL编码value = URLEncoder.encode(value, "UTF-8");System.out.println("存储数据："+value);Cookie cookie = new Cookie("username",value);//设置存活时间   ，1周 7天cookie.setMaxAge(60*60*24*7);//2. 发送Cookie，responseresponse.addCookie(cookie);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}
}

//cookie-Servlet-B.javapackage com.itheima.web.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;
import java.net.URLDecoder;@WebServlet("/bServlet")
public class BServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//获取Cookie//1. 获取Cookie数组Cookie[] cookies = request.getCookies();//2. 遍历数组for (Cookie cookie : cookies) {//3. 获取数据String name = cookie.getName();if("username".equals(name)){String value = cookie.getValue();//URL解码value = URLDecoder.decode(value,"UTF-8");System.out.println(name+":"+value);break;}}}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}
}

Cookie原理

Cookie的实现是基于HTTP协议的

响应头：set-cookie 服务器看到这个头就知道你要给我传Cookie了

请求头：cookie 服务器看到这个头就知道我该给客户端传Cookie了

Cookie使用细节（Cookie持久化）

        //设置存活时间   ，1周 7天cookie.setMaxAge(60*60*24*7);

        String value = "张三";//URL编码value = URLEncoder.encode(value, "UTF-8");System.out.println("存储数据："+value);Cookie cookie = new Cookie("username",value);
-----------------------------------------------------------//URL解码value = URLDecoder.decode(value,"UTF-8");System.out.println(name+":"+value);

Session基本使用(更安全)

//session-SessionDemo-1.javapackage com.itheima.web.session;import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;@WebServlet("/demo1")
public class SessionDemo1 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//存储到Session中//1. 获取Session对象HttpSession session = request.getSession();System.out.println(session);//2. 存储数据session.setAttribute("username","zs");}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}
}

//session-SessionDemo-2package com.itheima.web.session;import javax.servlet.ServletException;
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;
import java.io.IOException;@WebServlet("/demo2")
public class SessionDemo2 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//获取数据，从session中//1. 获取Session对象HttpSession session = request.getSession();System.out.println(session);// 销毁session.invalidate();//2. 获取数据Object username = session.getAttribute("username");System.out.println(username);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}
}

Session原理

Session是基于Cookie实现的，Session的地址值是永远不变的

Session使用细节（Session不能长期存储数据）

用于关闭浏览器后再打开仍保持用户登录状态

用于退出用户登录

        // 销毁session.invalidate();

小结

购物车信息：Cookie

用户登录信息：Session

账户密码的“记住我”功能：Cookie

验证码（防止暴力注册）：Session

案例

jsp（调用html与css等实现前端界面）——web（对用户输入的数据进行验证和对其他jsp的跳转）——service（将mapper实现的sql方法调用，获取sqlsession连接池，获取usermapper文件中的方法，调用方法，释放资源）——mapper（对数据库简单的增删改查定义一些实现方法）——util（工具类，生成动态验证码，定义静态代码块连接池）——pojo（实体类，用户信息实体类，品牌实体类）

在哪填充记录的cookie呢——在login.jsp中，使用PL表达式

<p>Username:<input id="username" name="username" value="${cookie.username.value}" type="text"></p><p>Password:<input id="password" name="password" value="${cookie.password.value}" type="password"></p>

package com.itheima.web;import com.itheima.pojo.User;
import com.itheima.service.UserService;import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet {private UserService service = new UserService();@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//1. 获取用户名和密码String username = request.getParameter("username");String password = request.getParameter("password");//获取复选框数据String remember = request.getParameter("remember");//2. 调用service查询User user = service.login(username, password);//3. 判断if(user != null){//登录成功，跳转到查询所有的BrandServlet//判断用户是否勾选记住我if("1".equals(remember)){// "1" 要写前面，用输入参数去比对，避免输入null导致比对异常//勾选了，发送Cookie/*** 登录后的页面要显示 用户名+欢迎您* <h1>${user.username},欢迎您</h1>* 属于一次会话的多个请求之间的数据传递* 所以要数据共享在Cookie或Session中*///1. 创建Cookie对象Cookie c_username = new Cookie("username",username);Cookie c_password = new Cookie("password",password);// 设置Cookie的存活时间c_username.setMaxAge( 60 * 60 * 24 * 7);c_password.setMaxAge( 60 * 60 * 24 * 7);//2. 发送response.addCookie(c_username);response.addCookie(c_password);}//将登陆成功后的user对象，存储到sessionHttpSession session = request.getSession();session.setAttribute("user",user);//改为动态路径String contextPath = request.getContextPath();response.sendRedirect(contextPath+"/selectAllServlet");}else {// 登录失败,// 存储错误信息到requestrequest.setAttribute("login_msg","用户名或密码错误");// 跳转到login.jsprequest.getRequestDispatcher("/login.jsp").forward(request,response);}}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}
}

//register.jsp<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>欢迎注册</title><link href="css/register.css" rel="stylesheet">
</head>
<body><div class="form-div"><div class="reg-content"><h1>欢迎注册</h1><span>已有帐号？</span> <a href="login.html">登录</a></div><form id="reg-form" action="/brand-demo/registerServlet" method="post"><table><tr><td>用户名</td><td class="inputs"><input name="username" type="text" id="username"><br><span id="username_err" class="err_msg" >${register_msg}</span></td></tr><tr><td>密码</td><td class="inputs"><input name="password" type="password" id="password"><br><span id="password_err" class="err_msg" style="display: none">密码格式有误</span></td></tr><tr><td>验证码</td><td class="inputs"><input name="checkCode" type="text" id="checkCode"><img id="checkCodeImg" src="/brand-demo/checkCodeServlet"><a href="#" id="changeImg" >看不清？</a></td></tr></table><div class="buttons"><input value="注 册" type="submit" id="reg_btn"></div><br class="clear"></form></div><script>document.getElementById("changeImg").onclick = function () {document.getElementById("checkCodeImg").src = "/brand-demo/checkCodeServlet?"+new Date().getMilliseconds();}</script>
</body>
</html>

//RegisterServlet.javapackage com.itheima.web;import com.itheima.pojo.User;
import com.itheima.service.UserService;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.*;
import java.io.IOException;@WebServlet("/registerServlet")
public class RegisterServlet extends HttpServlet {private UserService service = new UserService();@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//1. 获取用户名和密码数据String username = request.getParameter("username");String password = request.getParameter("password");User user = new User();user.setUsername(username);user.setPassword(password);// 获取用户输入的验证码String checkCode = request.getParameter("checkCode");// 程序生成的验证码，从Session获取HttpSession session = request.getSession();String checkCodeGen = (String) session.getAttribute("checkCodeGen");// 比对if(!checkCodeGen.equalsIgnoreCase(checkCode)){request.setAttribute("register_msg","验证码错误");request.getRequestDispatcher("/register.jsp").forward(request,response);// 不允许注册return;}//2. 调用service 注册boolean flag = service.register(user);//3. 判断注册成功与否if(flag){//注册功能，跳转登陆页面request.setAttribute("register_msg","注册成功，请登录");request.getRequestDispatcher("/login.jsp").forward(request,response);}else {//注册失败，跳转到注册页面request.setAttribute("register_msg","用户名已存在");request.getRequestDispatcher("/register.jsp").forward(request,response);}}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}
}

//CheckCodeServlet.javapackage com.itheima.web;import com.itheima.util.CheckCodeUtil;import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;@WebServlet("/checkCodeServlet")
public class CheckCodeServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// 生成验证码ServletOutputStream os = response.getOutputStream();String checkCode = CheckCodeUtil.outputVerifyImage(100, 50, os, 4);// 存入SessionHttpSession session = request.getSession();session.setAttribute("checkCodeGen",checkCode);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}
}

//工具类 CheckCodeUtil.javapackage com.itheima.util;import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.*;
import java.util.Arrays;
import java.util.Random;/*** 生成验证码工具类*/
public class CheckCodeUtil {public static final String VERIFY_CODES = "123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";private static Random random = new Random();public static void main(String[] args) throws IOException {OutputStream fos = new FileOutputStream("d://a.jpg");String checkCode = CheckCodeUtil.outputVerifyImage(100, 50, fos, 4);System.out.println(checkCode);}/*** 输出随机验证码图片流,并返回验证码值（一般传入输出流，响应response页面端，Web项目用的较多）** @param width 图片宽度* @param height 图片高度* @param os  输出流* @param verifySize 数据长度* @return 验证码数据* @throws IOException*/public static String outputVerifyImage(int width, int height, OutputStream os, int verifySize) throws IOException {String verifyCode = generateVerifyCode(verifySize);outputImage(width, height, os, verifyCode);return verifyCode;}/*** 使用系统默认字符源生成验证码** @param verifySize 验证码长度* @return*/public static String generateVerifyCode(int verifySize) {return generateVerifyCode(verifySize, VERIFY_CODES);}/*** 使用指定源生成验证码** @param verifySize 验证码长度* @param sources    验证码字符源* @return*/public static String generateVerifyCode(int verifySize, String sources) {// 未设定展示源的字码，赋默认值大写字母+数字if (sources == null || sources.length() == 0) {sources = VERIFY_CODES;}int codesLen = sources.length();Random rand = new Random(System.currentTimeMillis());StringBuilder verifyCode = new StringBuilder(verifySize);for (int i = 0; i < verifySize; i++) {verifyCode.append(sources.charAt(rand.nextInt(codesLen - 1)));}return verifyCode.toString();}/*** 生成随机验证码文件,并返回验证码值 (生成图片形式，用的较少)** @param w* @param h* @param outputFile* @param verifySize* @return* @throws IOException*/public static String outputVerifyImage(int w, int h, File outputFile, int verifySize) throws IOException {String verifyCode = generateVerifyCode(verifySize);outputImage(w, h, outputFile, verifyCode);return verifyCode;}/*** 生成指定验证码图像文件** @param w* @param h* @param outputFile* @param code* @throws IOException*/public static void outputImage(int w, int h, File outputFile, String code) throws IOException {if (outputFile == null) {return;}File dir = outputFile.getParentFile();//文件不存在if (!dir.exists()) {//创建dir.mkdirs();}try {outputFile.createNewFile();FileOutputStream fos = new FileOutputStream(outputFile);outputImage(w, h, fos, code);fos.close();} catch (IOException e) {throw e;}}/*** 输出指定验证码图片流** @param w* @param h* @param os* @param code* @throws IOException*/public static void outputImage(int w, int h, OutputStream os, String code) throws IOException {int verifySize = code.length();BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);Random rand = new Random();Graphics2D g2 = image.createGraphics();g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);// 创建颜色集合，使用java.awt包下的类Color[] colors = new Color[5];Color[] colorSpaces = new Color[]{Color.WHITE, Color.CYAN,Color.GRAY, Color.LIGHT_GRAY, Color.MAGENTA, Color.ORANGE,Color.PINK, Color.YELLOW};float[] fractions = new float[colors.length];for (int i = 0; i < colors.length; i++) {colors[i] = colorSpaces[rand.nextInt(colorSpaces.length)];fractions[i] = rand.nextFloat();}Arrays.sort(fractions);// 设置边框色g2.setColor(Color.GRAY);g2.fillRect(0, 0, w, h);Color c = getRandColor(200, 250);// 设置背景色g2.setColor(c);g2.fillRect(0, 2, w, h - 4);// 绘制干扰线Random random = new Random();// 设置线条的颜色g2.setColor(getRandColor(160, 200));for (int i = 0; i < 20; i++) {int x = random.nextInt(w - 1);int y = random.nextInt(h - 1);int xl = random.nextInt(6) + 1;int yl = random.nextInt(12) + 1;g2.drawLine(x, y, x + xl + 40, y + yl + 20);}// 添加噪点// 噪声率float yawpRate = 0.05f;int area = (int) (yawpRate * w * h);for (int i = 0; i < area; i++) {int x = random.nextInt(w);int y = random.nextInt(h);// 获取随机颜色int rgb = getRandomIntColor();image.setRGB(x, y, rgb);}// 添加图片扭曲shear(g2, w, h, c);g2.setColor(getRandColor(100, 160));int fontSize = h - 4;Font font = new Font("Algerian", Font.ITALIC, fontSize);g2.setFont(font);char[] chars = code.toCharArray();for (int i = 0; i < verifySize; i++) {AffineTransform affine = new AffineTransform();affine.setToRotation(Math.PI / 4 * rand.nextDouble() * (rand.nextBoolean() ? 1 : -1), (w / verifySize) * i + fontSize / 2, h / 2);g2.setTransform(affine);g2.drawChars(chars, i, 1, ((w - 10) / verifySize) * i + 5, h / 2 + fontSize / 2 - 10);}g2.dispose();ImageIO.write(image, "jpg", os);}/*** 随机颜色** @param fc* @param bc* @return*/private static Color getRandColor(int fc, int bc) {if (fc > 255) {fc = 255;}if (bc > 255) {bc = 255;}int r = fc + random.nextInt(bc - fc);int g = fc + random.nextInt(bc - fc);int b = fc + random.nextInt(bc - fc);return new Color(r, g, b);}private static int getRandomIntColor() {int[] rgb = getRandomRgb();int color = 0;for (int c : rgb) {color = color << 8;color = color | c;}return color;}private static int[] getRandomRgb() {int[] rgb = new int[3];for (int i = 0; i < 3; i++) {rgb[i] = random.nextInt(255);}return rgb;}private static void shear(Graphics g, int w1, int h1, Color color) {shearX(g, w1, h1, color);shearY(g, w1, h1, color);}private static void shearX(Graphics g, int w1, int h1, Color color) {int period = random.nextInt(2);boolean borderGap = true;int frames = 1;int phase = random.nextInt(2);for (int i = 0; i < h1; i++) {double d = (double) (period >> 1)* Math.sin((double) i / (double) period+ (6.2831853071795862D * (double) phase)/ (double) frames);g.copyArea(0, i, w1, 1, (int) d, 0);if (borderGap) {g.setColor(color);g.drawLine((int) d, i, 0, i);g.drawLine((int) d + w1, i, w1, i);}}}private static void shearY(Graphics g, int w1, int h1, Color color) {int period = random.nextInt(40) + 10; // 50;boolean borderGap = true;int frames = 20;int phase = 7;for (int i = 0; i < w1; i++) {double d = (double) (period >> 1)* Math.sin((double) i / (double) period+ (6.2831853071795862D * (double) phase)/ (double) frames);g.copyArea(i, 0, 1, h1, 0, (int) d);if (borderGap) {g.setColor(color);g.drawLine(i, (int) d, i, 0);g.drawLine(i, (int) d + h1, i, h1);}}}
}

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