学习Java的日子 Day59 学生管理系统 web1.0版本

Day59 学生管理系统 web1.0

1.项目需求

有两个角色，老师和学生，相同的功能提取到父类用户角色

在这里插入图片描述

2.数据库搭建

设计学生表

在这里插入图片描述

设计老师表

在这里插入图片描述

插入数据 (超级管理员)

在这里插入图片描述

设计学科表

在这里插入图片描述

3.项目搭建

处理基础页面，分包，实体类，导入数据库

项目结构，导入数据库相关内容

在这里插入图片描述

数据库工具类

package com.qf.utils;public class DBUtils {private static DruidDataSource pool;private static ThreadLocal<Connection> local;static{Properties properties = new Properties();try {properties.load(DBUtils.class.getClassLoader().getResourceAsStream("DBConfig.properties"));} catch (IOException e) {throw new RuntimeException(e);}String driverClassName = properties.getProperty("driverClassName");String url = properties.getProperty("url");String username = properties.getProperty("username");String password = properties.getProperty("password");int maxActive = Integer.parseInt(properties.getProperty("maxActive"));//初始化数据库连接池pool = new DruidDataSource();//设置参数pool.setDriverClassName(driverClassName);pool.setUrl(url);pool.setUsername(username);pool.setPassword(password);pool.setMaxActive(maxActive);local = new ThreadLocal<>();}/*** 获取连接对象*/public static Connection getConnection() throws SQLException {Connection connection = local.get();//获取当前线程的Connection对象if(connection == null){connection = pool.getConnection();//获取数据库连接池里的连接对象local.set(connection);//将Connection对象添加到local中}return connection;}/*** 关闭资源*/public static void close(Connection connection, Statement statement, ResultSet resultSet){if(resultSet != null){try {resultSet.close();} catch (SQLException e) {throw new RuntimeException(e);}}if(statement != null){try {statement.close();} catch (SQLException e) {throw new RuntimeException(e);}}if(connection != null){try {if(connection.getAutoCommit()){connection.close();local.set(null);}} catch (SQLException e) {throw new RuntimeException(e);}}}/*** 开启事务*/public static void startTransaction() throws SQLException {Connection connection = getConnection();connection.setAutoCommit(false);}/*** 提交事务*/public static void commit() throws SQLException {Connection connection = local.get();if(connection != null){connection.commit();connection.close();local.set(null);}}public static void rollback() throws SQLException {Connection connection = local.get();if(connection != null){connection.rollback();connection.close();local.set(null);}}/*** 更新数据（添加、删除、修改）*/public static int commonUpdate(String sql,Object... params) throws SQLException {Connection connection = null;PreparedStatement statement = null;try {connection = getConnection();statement = connection.prepareStatement(sql);paramHandler(statement,params);int num = statement.executeUpdate();return num;}finally {close(connection,statement,null);}}/*** 添加数据 - 主键回填(主键是int类型可以返回)*/public static int commonInsert(String sql,Object... params) throws SQLException {Connection connection = null;PreparedStatement statement = null;ResultSet resultSet = null;try {connection = getConnection();statement = connection.prepareStatement(sql,PreparedStatement.RETURN_GENERATED_KEYS);paramHandler(statement,params);statement.executeUpdate();resultSet = statement.getGeneratedKeys();int primaryKey = 0;if(resultSet.next()){primaryKey = resultSet.getInt(1);}return primaryKey;}finally {close(connection,statement,resultSet);}}/*** 查询多个数据*/public static <T> List<T> commonQueryList(Class<T> clazz,String sql, Object... params) throws SQLException{Connection connection = null;PreparedStatement statement = null;ResultSet resultSet = null;try {connection = getConnection();statement = connection.prepareStatement(sql);paramHandler(statement,params);resultSet = statement.executeQuery();//获取表数据对象ResultSetMetaData metaData = resultSet.getMetaData();//获取字段个数int count = metaData.getColumnCount();List<T> list = new ArrayList<>();while(resultSet.next()){T t = null;try {t = clazz.newInstance();} catch (InstantiationException e) {throw new RuntimeException(e);} catch (IllegalAccessException e) {throw new RuntimeException(e);}//获取字段名及数据for (int i = 1; i <= count; i++) {String fieldName = metaData.getColumnName(i);Object fieldVal = resultSet.getObject(fieldName);setField(t,fieldName,fieldVal);}list.add(t);}return list;} finally {DBUtils.close(connection,statement,resultSet);}}/*** 查询单个数据*/public static <T> T commonQueryObj(Class<T> clazz,String sql, Object... params) throws SQLException{Connection connection = null;PreparedStatement statement = null;ResultSet resultSet = null;try {connection = getConnection();statement = connection.prepareStatement(sql);paramHandler(statement,params);resultSet = statement.executeQuery();//获取表数据对象ResultSetMetaData metaData = resultSet.getMetaData();//获取字段个数int count = metaData.getColumnCount();if(resultSet.next()){T t = null;try {t = clazz.newInstance();} catch (InstantiationException e) {throw new RuntimeException(e);} catch (IllegalAccessException e) {throw new RuntimeException(e);}//获取字段名及数据for (int i = 1; i <= count; i++) {String fieldName = metaData.getColumnName(i);Object fieldVal = resultSet.getObject(fieldName);setField(t,fieldName,fieldVal);}return t;}} finally {DBUtils.close(connection,statement,resultSet);}return null;}/*** 获取当前表的总条数*/public static int getAllCount(String table) throws SQLException {Connection connection = getConnection();String sql = "select count(1) from " + table;PreparedStatement statement = connection.prepareStatement(sql);ResultSet resultSet = statement.executeQuery();if(resultSet.next()){int allCount = resultSet.getInt(1);return allCount;}return 0;}/*** 处理statement对象参数数据的处理器*/private static void paramHandler(PreparedStatement statement,Object... params) throws SQLException {for (int i = 0; i < params.length; i++) {statement.setObject(i+1,params[i]);}}/*** 获取当前类及其父类的属性对象* @param clazz class对象* @param name 属性名* @return 属性对象*/private static Field getField(Class<?> clazz,String name){for(Class<?> c = clazz;c != null;c = c.getSuperclass()){try {Field field = c.getDeclaredField(name);return field;} catch (NoSuchFieldException e) {} catch (SecurityException e) {}}return null;}/*** 设置对象中的属性* @param obj 对象* @param name 属性名* @param value 属性值*/private static void setField(Object obj,String name,Object value){Field field = getField(obj.getClass(), name);if(field != null){field.setAccessible(true);try {field.set(obj, value);} catch (IllegalArgumentException e) {e.printStackTrace();} catch (IllegalAccessException e) {e.printStackTrace();}}}
}

创建首页 Welcome.html

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>首页</title>
</head>
<body><h1>欢迎来到学生管理系统页面</h1><hr><span>请选择你的操作:</span><br/><a href="login.jsp">登录</a><a href="register.jsp">注册</a>
</body>
</html>

web.xml配置首页

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"version="4.0">//设置首页<welcome-file-list><welcome-file>Welcome.html</welcome-file></welcome-file-list></web-app>

实现类创建

User

package com.qf.pojo;public class User {private String username;private String password;private String name;private String sex;private int age;//无参构造，有参构造，get，set，toString方法省略

Teacher

public class Teacher extends User{private int course;public Teacher() {}//无参构造，有参构造带父类的属性，get，set，toString方法省略

Student

package com.qf.pojo;public class Student extends User{private String hobbies;//无参构造，有参构造带父类的属性，get，set，toString方法省略

Course

package com.qf.pojo;public class Course {private int id;private String name;//无参构造，有参构造，get，set，toString方法省略

4.注册功能

注册流程图

在这里插入图片描述

注册逻辑 RegisterServlet

注意：老师不用注册是管理员自动分配账号，而学生需要注册

注册逻辑：

1.设置请求、响应编码格式

2.获取请求中的数据

3.通过username查询数据库中的学生对象

4.通过学生对象进行非空判断

没找到就允许注册，将数据插入到学生表中，利用重定向跳转到登录页面

在数据库中就不允许注册，利用重定向跳转到注册页面

注意：

request.getParameter表示获取前端的参数，参数为页面提交的数据（二进制流不使用这个）

request.getAttribute获取请求对象(请求域)中的数据

package com.qf.Servlet;@WebServlet("/RegisterServlet")
public class RegisterServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request, response);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//设置请求、响应编码格式request.setCharacterEncoding("UTF-8");response.setContentType("text/html;charset=UTF-8");//获取请求中的数据String username = request.getParameter("username");String password = request.getParameter("password");String name = request.getParameter("name");String sex = request.getParameter("sex");String age = request.getParameter("age");String[] hobbies = request.getParameterValues("hobbies");//通过username查询数据库中的学生对象Student student = null;try {student = DBUtils.commonQueryObj(Student.class, "select * from student where username=?", username);} catch (SQLException e) {throw new RuntimeException(e);}if(student == null){//在数据库中没有找到，说明没有这个学生，就允许注册//将数据插入到学生表中try {DBUtils.commonUpdate("insert into student(username,password,name,sex,age,hobbies) values(?,?,?,?,?,?)",username,password,name,sex,age, StringUtils.handleArray(hobbies));} catch (SQLException e) {throw new RuntimeException(e);}//利用重定向跳转到登录页面response.sendRedirect("login.jsp");}else{//不允许注册//展示信息,将数据直接设置在request中//将数据存储到请求域中，生命周期非常短，一来一回就死亡了//请求发送后，响应后就死亡了request.setAttribute("msg","注册失败 -- 账号已存在");//利用转发跳转到注册页面request.getRequestDispatcher("register.jsp").forward(request,response);}}
}

理解以下代码

请求域对象都是使用request

//展示提示信息，将数据存储到请求对象(请求域)中，生命周期非常短，一来一回就死亡了,请求发送后，响应后就死亡了
//只是在web容器内部流转，仅仅是请求处理阶段
request.setAttribute("msg","注册失败 -- 账号已存在");//利用转发跳转到注册页面
request.getRequestDispatcher("register.jsp").forward(request,response);   //register.jsp前端获取
<%String msg = (String) request.getAttribute("msg");
%>

注册页面 register.jsp

JSP的脚本：JSP定义Java代码的方式

可以简单理解为几个标签，带有<% % >

<% java代码 %>：写的是java的逻辑代码

<%= java‘代码 %>：写的java代码，会输出展示到页面上。输出语句中可以定义什么，jsp页面就会显示什么内容

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>Title</title>
</head>
<body><!-- 在jsp中写java代码用<% %> 包裹，拿到请求对象(请求域)中的提示信息：注册失败 -- 账号已存在 -->
<%String msg = (String) request.getAttribute("msg");
%>
<!-- 在页面中展示提示信息  三目运算符 第一次进入为空不展示-->
<%= (msg != null)? msg:"" %> <h1>注册页面</h1>
<form action="RegisterServlet" method="post">账号：<input type="text" name="username"/><br/>密码：<input type="password" name="password"/><br/>姓名：<input type="text" name="name"/><br/>年龄：<input type="text" name="age"/><br/>性别：<input type="radio" name="sex" value="man" checked="checked"/>男<input type="radio" name="sex" value="woman"/>女<br/>爱好：<input type="checkbox" name="hobbies" value="football"/>足球<input type="checkbox" name="hobbies" value="basketball"/>篮球<input type="checkbox" name="hobbies" value="shop"/>购物<br/><input type="submit" value="注册"/><input type="button" value="返回" οnclick="goWelcome()"></form><script type="text/javascript">function goWelcome(){window.location = "http://localhost:8080/StudentManagementSystem_Web_exploded/";}
</script>
</body>
</html>

优化注册页面 register.jsp

<!-- 在jsp中写java代码用<% %> 包裹 -->
<%String msg = (String) request.getAttribute("msg");
%>
<!-- 在页面中展示数据  三目运算符 第一次进入为空不展示-->
<%= (msg != null)? msg : "" %>//上面的不要，直接用这一行代码展示msg(页面会自动拿到数据)
${msg}

因为hobbies是一个字符串数组，所以写一个工具类，让其拼接字符串

StringUtils

利用反射操作数组

package com.qf.utils;import java.lang.reflect.Array;public class StringUtils {public static String handleArray(Object[] os){StringBuffer sb = new StringBuffer();for (int i=0;i< Array.getLength(os);i++){//利用反射操作数组Arrayif (i!=0){sb.append(",");}//获取当前下标上的元素Object element = Array.get(os, i);sb.append(element);}//        for (Object element : os) {
//            if(sb.length() !=0){
//                sb.append(",");
//            }
//            sb.append(element);
//        }return sb.toString();}
}

运行结果：

在这里插入图片描述

点击注册，输入数据，注册成功（账号没有在数据库里就会注册成功）跳转到登录页面，失败会跳转到注册页面,页面上会显示提示信息注册失败 – 账号已存在

在这里插入图片描述

查看数据库

在这里插入图片描述

5.登录页面

在这里插入图片描述

LoginServlet

1.设置请求、响应编码格式

2.获取请求中的数据

3.验证码是否输入正确

不正确登录失败 - 验证码错误

4.正确，通过username、password查询数据库中的用户对象

5.通过用户对象判断（是否在数据库中）
  					登录成功，利用重定向跳转到详情页面（凭证添加到Cookie，数据存储到Session）登录失败 – 账号或密码错误，利用重定向跳转到登录页面

package com.qf.Servlet;@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request, response);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//设置请求、响应编码格式request.setCharacterEncoding("UTF-8");response.setContentType("text/html;charset=UTF-8");//获取请求中的数据String username = request.getParameter("username");String password = request.getParameter("password");String userCode = request.getParameter("userCode");String rememberMe = request.getParameter("rememberMe");String role = request.getParameter("role");String sysCode = (String) request.getSession().getAttribute("sysCode");if (sysCode.equalsIgnoreCase(userCode)){ //验证码是否输入正确User user=null;try {if ("student".equals(role)){user=DBUtils.commonQueryObj(Student.class,"select * from student where username=? and password=?",username,password);} else if ("teacher".equals(role)) {user=DBUtils.commonQueryObj(Teacher.class,"select * from teacher where username=? and password=?", username, password);}} catch (SQLException e) {throw new RuntimeException(e);}if (user!=null){//登录成功//判断是否记住我if(rememberMe != null){//将凭证添加到Cookie中//cookie保存在浏览器中response.addCookie(CookieUtils.createCookie("username",user.getUsername(),60*60*24*5));response.addCookie(CookieUtils.createCookie("name",user.getName(),60*60*24*5));response.addCookie(CookieUtils.createCookie("role",role,60*60*24*5));}//将数据存储到Session中(后续需要使用的)//浏览器向服务器发送一个请求，服务器会生成一个session对象，保存在服务器中HttpSession session = request.getSession();session.setAttribute("username",user.getUsername());session.setAttribute("name",user.getName());session.setAttribute("role",role);response.sendRedirect("index.jsp");}else{//登录失败 -- 账号或密码错误request.setAttribute("msg","登录失败--账号或密码错误");request.getRequestDispatcher("login.jsp").forward(request,response);}}else{//登录失败 - 验证码错误//将数据发送到请求对象(请求域)中，时间在一瞬间，交互很短//我们使用request.setAttribute()方法设置了一个名为 “msg” 的属性，并将其值设置为 “登录失败--验证码错误”。// 然后，我们可以通过请求转发（forward）将这个属性传递给其他组件，如另一个Servlet或JSP页面request.setAttribute("msg","登录失败--验证码错误");request.getRequestDispatcher("login.jsp").forward(request,response);}}
}

login.jsp

关注验证码的写法，还有就是刷新验证码和点击验证码自动刷新

注意设置刷新验证码的函数

<%@ page import="java.net.URLDecoder" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>Title</title>
</head>
<body><!-- 记住我的代码 -->
<%Cookie[] cookies = request.getCookies();if(cookies != null){int count = 0;for (Cookie cookie : cookies) {String name = cookie.getName();String value = URLDecoder.decode(cookie.getValue(),"UTF-8");if("username".equals(name)){session.setAttribute("username",value);count++;}if("name".equals(name)){session.setAttribute("name",value);count++;}if("role".equals(name)){session.setAttribute("role",value);count++;}}if(count == 3){response.sendRedirect("index.jsp");}}
%><!-- 判断登录结果，成功还是失败，提示信息显示在页面上方 -->
<%String msg = (String) request.getAttribute("msg");
%>
<%= (msg!=null)?msg:""%><h1>登录页面</h1>
<!--点击登录页面，会方式两次请求，一次是LoginServlet，第二次是CodeServlet-->
<form action="LoginServlet" method="post">账号：<input type="text" name="username"/><br/>密码：<input type="password" name="password"/><br/>验证码：<input type="text" name="userCode"/><img src="CodeServlet" width="120px" height="30px" οnclick="refresh()"><a href="#" οnclick="refresh()">刷新</a><br/>记住我：<input type="checkbox" name="rememberMe"/><br/>角色：<select name="role"><option value="student">学生</option><option value="teacher">老师</option></select><br/><input type="submit" value="登录"/><input type="button" value="返回" οnclick="goWelcome()"/>
</form><script type="text/javascript">function goWelcome(){window.location = "welcome.html";}//刷新验证码img = document.getElementsByTagName("img")[0];function refresh(){img.src = "CodeServlet?" + new Date();}</script></body>
</html>

优化login.jsp

<%@ page import="java.net.URLDecoder" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>Title</title>
</head>
<body><!-- 记住我的java代码直接写出去 rememberMe.jsp，然后导包 -->
<%@include file="rememberMe.jsp"%><!-- 判断登录结果，成功还是失败，显示在页面上方 -->
<%--<%--%>
<%--    String msg = (String) request.getAttribute("msg");--%>
<%--%>--%>
<%--<%= (msg!=null)?msg:""%>--%>${msg}<h1>登录页面</h1>
<!--点击登录页面，会方式两次请求，一次是LoginServlet，第二次是CodeServlet-->
<form action="LoginServlet" method="post">账号：<input type="text" name="username"/><br/>密码：<input type="password" name="password"/><br/>...省略</body>
</html>

java代码直接写出去 rememberMe.jsp，然后导包

rememberMe.jsp

<%@ page import="java.net.URLDecoder" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%Cookie[] cookies = request.getCookies();if(cookies != null){int count = 0;for (Cookie cookie : cookies) {String name = cookie.getName();String value = URLDecoder.decode(cookie.getValue(),"UTF-8");if("username".equals(name)){session.setAttribute("username",value);count++;}if("name".equals(name)){session.setAttribute("name",value);count++;}if("role".equals(name)){session.setAttribute("role",value);count++;}}if(count == 3){response.sendRedirect("index.jsp");}}
%>

5.1 绘制验证码

CodeServlet

1.创建画布(前提定义宽高)

2.通过画布获取画笔

3.设置背景色 – 填充矩形【利用画笔】

4.设置验证码

创建验证码数字数组、颜色数组

利用随机数进行获取随机下标从而获取随机数字和颜色

设置随机颜色

设置字体（字体,样式,大小）

设置单个验证码

StringBffer拼接成验证码

设置干扰线

6.ImageIO将画布以jpg形式的文件传出给客户端

package com.qf.Servlet;@WebServlet("/CodeServlet")
public class CodeServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request, response);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//验证码是图片，不需要编码格式//设置宽高的变量int width = 120;int height = 30;//创建画布BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);//获取画笔Graphics graphics = image.getGraphics();//设置背景色 -- 填充矩形graphics.setColor(Color.BLUE);//选择颜色graphics.fillRect(0,0,width,height);//填充整个图片区域//设置验证码Random random = new Random();String[] codes = {"A","B","C","D","E","F","G","H","J","K","M","N","P","Q","R","S","T","U","V","W","X","Y","Z","0","1","2","3","4","5","6","7","8","9"};Color[] colors = {Color.CYAN,Color.BLACK,Color.GREEN,Color.PINK,Color.WHITE,Color.RED,Color.ORANGE};StringBuffer sb = new StringBuffer();for (int i = 0; i < 4; i++) {String randomCode = codes[random.nextInt(codes.length)];//随机内容Color randomColor = colors[random.nextInt(colors.length)];//随机颜色graphics.setColor(randomColor);//设置随机颜色graphics.setFont(new Font("宋体",Font.BOLD,20+random.nextInt(10)));//设置字体（字体,样式,大小）graphics.drawString(randomCode,20+i*25,15+random.nextInt(10));//设置单个验证码sb.append(randomCode);}//将系统验证码设置到Session对象中(会话对象),存储在服务器中//浏览器向服务器发送一个请求，服务器会生成一个session对象HttpSession session = request.getSession();//获取请求里的JSESSIONID(客户端Cookie里的数据)，如果没有就创建Session对象，如果有就从Session容器中获取会话对象session.setAttribute("sysCode",sb.toString());//键值对，键是String类型，值是Object对象//设置干扰线graphics.setColor(Color.YELLOW);for (int i = 0; i < 3; i++) {graphics.drawLine(random.nextInt(width),random.nextInt(height),random.nextInt(width),random.nextInt(height));//绘制直线(x1,y1,x2,y2) -> 两点为一线}//将画布以jpg形式的文件传出给客户端，ImageIO工具ImageIO.write(image,"jpg",response.getOutputStream());}
}

5.2 分析验证码功能制作

在这里插入图片描述

注册功能中的request.getAttribute：将数据直接设置在request中，利用request调用，存储时间短

验证码功能中的HttpSession session = request.getSession(); 浏览器向服务器发送一个请求，服务器会生成一个session对象，利用session（request.getSession() ）去调用，30分钟

区别：session的过期时间是30分钟，可以调，长时间的属性可以放在session，一瞬间的数据可以放在jsp里请求对象request里

session对象的作用域为一次会话，通常浏览器不关闭，保存的值就不会消失，当然也会出现session超时(tomcat默认为30分钟)

session.getAttribute(“”) 取到的类型是是object，所以赋值前要强转一下，转成你需要的类型

Session的基本工作原理：

用户访问Web应用程序时，服务器为每个用户创建一个唯一的Session对象。
服务器将Session ID 分配给每个Session对象，并将Session ID 存储在用户的浏览器中的Cookie中。Session ID 在服务器端和客户端之间用于标识Session。
当用户发送请求时，服务器使用Session ID 来查找相应的Session对象。
服务器可以将数据存储在Session对象中，以便在用户的不同请求之间共享。
当用户关闭浏览器或Session超时时，Session对象被销毁。

session的相关使用

1.获取Session对象,使用的是request对象
HttpSession session = request.getSession();
2.存储数据到 session 域中
session.setAttribute(String name, Object o)
3.根据 key，获取值
session.getAttribute(String name)

验证码功能就是把把验证码存在session对象中，设置键值对属性

输入一个验证码，会寻找对应的session ID，获取对应的值，这个有30分钟，不同的验证码请求有不同的ID

	//将系统验证码设置到Session对象中(会话对象)//浏览器向服务器发送一个请求，服务器会生成一个session对象HttpSession session = request.getSession();//获取请求里的JSESSIONID(客户端Cookie里的数据)，如果没有获取到就创建Session对象，如果有就从Session容器中获取会话对象session.setAttribute("sysCode",sb.toString());//键值对，键是String类型，值是Object对象

从Session对象中取出来判断

request.getSession() -->获取到这个session对象，再获取里面的value

     //从Session对象中获取系统的验证码String sysCode = (String) request.getSession().getAttribute("sysCode");if(sysCode.equalsIgnoreCase(userCode)){......}

结论

1.Cookie是用来保证用户在未登录情况下的身份识别

2.Session是用来保存用户登录后的数据

3.Session是存储在服务端，而Cookie是存储在客户端

4.购物车、记住我功能：使用Cookie来存储

5.以登录用户的名称展示、验证码：使用Session来存储

运行结果：

输入一个在数据库有的数据

在这里插入图片描述

5.3 记住我(存Session、存Cookie)

流程图

在这里插入图片描述

实现：存Session、存Cookie

LoginServlet

添加存凭证

1.当第一次登录时，点击了“记住我”，就会存凭证【username、name、role合起来是一个凭证】存在Cookie中

2.再次登录就会判断，是否有凭证
  有，直接跳详情页面，不过在跳转前会将凭证存在session中【因为详情页展示需要session的数据】
没有，就不管，就用户直接输入登录

package com.qf.Servlet;@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {String sysCode = (String) request.getSession().getAttribute("sysCode");if (sysCode.equalsIgnoreCase(userCode)){ //验证码是否输入正确User user=null;try {if ("student".equals(role)){user=DBUtils.commonQueryObj(Student.class,"select * from student where username=? and password=?",username,password);} else if ("teacher".equals(role)) {user=DBUtils.commonQueryObj(Teacher.class,"select * from teacher where username=? and password=?", username, password);}} catch (SQLException e) {throw new RuntimeException(e);}if (user!=null){//登录成功//判断是否记住我if(rememberMe != null){//将凭证添加到Cookie中//cookie保存在客户端中（键值对都是String类型）response.addCookie(CookieUtils.createCookie("username",user.getUsername(),60*60*24*5));response.addCookie(CookieUtils.createCookie("name",user.getName(),60*60*24*5));response.addCookie(CookieUtils.createCookie("role",role,60*60*24*5));}//将凭证数据存储到Session中//浏览器向服务器发送一个请求，服务器会生成一个session对象，保存在服务器中HttpSession session = request.getSession();session.setAttribute("username",user.getUsername());session.setAttribute("name",user.getName());session.setAttribute("role",role);response.sendRedirect("index.jsp");}else{//登录失败 -- 账号或密码错误request.setAttribute("msg","登录失败--账号或密码错误");request.getRequestDispatcher("login.jsp").forward(request,response);}

添加cookie工具类

CookieUtils

package com.qf.utils;public class CookieUtils {public static Cookie createCookie(String name,String value,int time)  {Cookie cookie=null;try {//数据中有中文，必须设置编码格式cookie= new Cookie(name, URLEncoder.encode(value, "UTF-8"));} catch (UnsupportedEncodingException e) {throw new RuntimeException(e);}cookie.setMaxAge(time);return  cookie;}
}

login.jsp

<%@ page import="java.net.URLDecoder" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>Title</title>
</head>
<body><!-- 记住我的代码 -->
<%Cookie[] cookies = request.getCookies();if(cookies != null){int count = 0;for (Cookie cookie : cookies) {String name = cookie.getName();//取数据时需要解码String value = URLDecoder.decode(cookie.getValue(),"UTF-8");if("username".equals(name)){//存储value值session.setAttribute("username",value);count++;}if("name".equals(name)){session.setAttribute("name",value);count++;}if("role".equals(name)){session.setAttribute("role",value);count++;}}if(count == 3){response.sendRedirect("index.jsp");}}
%><!-- 判断登录结果，成功还是失败，显示在页面上方 -->
<%String msg = (String) request.getAttribute("msg");
%>
<%= (msg!=null)?msg:""%><h1>登录页面</h1>.......

Cookie:

1.创建Cookie对象，并设置值:
Cookie cookie = new Cookie("key","value");
2.发送Cookie到客户端使用的是Reponse对象:
response.addCookie(cookie);

3.获取Cookie：使用Request对象获取Cookie数组:
Cookie[] cookies = request.getCookies();

6.详情页

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>Title</title>
</head>
<body>
<%//取出登录页面存储的session对象String username = (String) session.getAttribute("username");String name = (String) session.getAttribute("name");String role = (String) session.getAttribute("role");
%><button onclick="safeExit()">安全退出</button>
<h1>详情页面</h1>
<h1>欢迎<%=name%><%=("student".equals(role))?"学员":""%><%=("teacher".equals(role))?"老师":""%>进入到学生管理系统</h1><a href="resetPassword.jsp">修改密码</a><%if("student".equals(role)){%>
<!-- 在这个servlet通过username找到这个学生，再跳转到信息修改页面 -->
<a href="StuInitModifyServlet?username=<%=username%>">修改信息</a>
<%}%><%if("teacher".equals(role)){%>
<a href="TeaInitModifyServlet?username=<%=username%>">修改信息</a>
<a href="#">查看所有学生</a>
<%}%><script type="text/javascript">function safeExit(){window.location = "SafeExitServlet";}
</script>
</body>
</html>

优化：

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%><html>
<head><title>Title</title>
</head>
<body>
<%--<%--%>
<%--    String username = (String) session.getAttribute("username");--%>
<%--    String name = (String) session.getAttribute("name");--%>
<%--    String role = (String) session.getAttribute("role");--%>
<%--%>--%><button onclick="safeExit()">安全退出</button>
<h1>详情页面</h1>
<%--<%=("student".equals(role))?"学员":""%>--%>
<%--${(role eq "student")?"学员":""}--%><h1>欢迎${name}${(role eq "student")?"学员":""}${(role eq "teacher")?"学员":""}进入到学生管理系统</h1><a href="resetPassword.jsp">修改密码</a><c:if test="${role eq 'student'}"><a href="StuInitModifyServlet?username=${username}">修改信息</a>
</c:if><%--<%if("student".equals(role)){%>--%>
<%--<!-- 在这个servlet通过username找到这个学生，再跳转到信息修改页面 -->--%>
<%--<a href="StuInitModifyServlet?username=<%=username%>">修改信息</a>--%>
<%--<%}%>--%><%--<%if("teacher".equals(role)){%>--%>
<%--<a href="TeaInitModifyServlet?username=<%=username%>">修改信息</a>--%>
<%--<a href="GetStuListServlet?curPage=1">查看所有学生</a>--%>
<%--<%}%>--%><c:if test="${role eq 'teacher'}"><a href="TeaInitModifyServlet?username=${usename}">修改信息</a><a href="GetStuListServlet?curPage=1">查看所有学生</a>
</c:if><script type="text/javascript">function safeExit(){window.location = "SafeExitServlet";}
</script>
</body>
</html>

8.安全退出(删Session、删Cookie)

删除账号所有信息 cookie，session

<button οnclick="safeExit()">安全退出</button>
<h1>详情页面</h1>
<h1>欢迎<%=name%><%=("student".equals(role))?"学员":""%><%=("teacher".equals(role))?"老师":""%>进入到学生管理系统</h1><script type="text/javascript">function safeExit(){window.location = "SafeExitServlet";}
</script>

SafeExitServlet

package com.qf.Servlet;
import com.qf.utils.CookieUtils;@WebServlet("/SafeExitServlet")
public class SafeExitServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request, response);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//删除Cookie里的数据//把时间设置为0，就是删除response.addCookie(CookieUtils.createCookie("username","",0));response.addCookie(CookieUtils.createCookie("name","",0));response.addCookie(CookieUtils.createCookie("role","",0));//删除Session里的数据HttpSession session = request.getSession();session.removeAttribute("username");session.removeAttribute("name");session.removeAttribute("role");//跳转response.sendRedirect("Welcome.html");}
}

9.修改密码

在这里插入图片描述

index.jsp

<button onclick="safeExit()">安全退出</button>
<h1>详情页面</h1>
<h1>欢迎<%=name%><%=("student".equals(role))?"学员":""%><%=("teacher".equals(role))?"老师":""%>进入到学生管理系统</h1><a href="resetPassword.jsp">修改密码</a>// ...省略

resetPassword.jsp

需要展示页面就要先获取session中的username

要用户输入原密码和新密码【对于为什么要原密码，就是在用户电脑在登录情况下被别人直接改密码】

注意1：对于ResetPasswordServlet查询用户对象，是需要username和role，怎么获取？

方案：在这个表单直接请求传过去（使用隐藏域），ResetPasswordServlet就可以在请求中取

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>Title</title>
</head>
<body><%//从前端页面中取出来数据(当前页面没用，但是后面的ResetPasswordServlet有用)String username = (String) session.getAttribute("username");String role = (String) session.getAttribute("role");//提示信息String msg = (String) request.getAttribute("msg");
%><%=(msg!=null)?msg:""%><form action="ResetPasswordServlet" method="post">//传入给后端ResetPasswordServlet<!--隐藏域，不会在页面中展示，但是发送请求后会携带到后端--><input type="hidden" name="username" value="<%=username%>"/><input type="hidden" name="role" value="<%=role%>"/>账号：<%=username%><br/>原密码：<input type="password" name="password"/><br/>新密码：<input type="password" name="newPassword"/><br/><input type="submit" value="修改"/><input type="button" value="返回" οnclick="goIndex()"/>
</form><script type="text/javascript">function goIndex(){window.location = "index.jsp";}
</script>
</body>
</html>

ResetPasswordServlet

1.设置请求、响应编码格式
2.获取请求中的数据
3.通过username、password查询数据库中的用户对象
4.通过用户对象进行非空判断
用户存在，判断角色修改密码，注意要做安全退出【不然在有记住我的情况下，第二次登录直接进来】

用户不存在，设置提示修改密码失败信息，又转发方式跳转回到修改密码页面

package com.qf.Servlet;@WebServlet("/ResetPasswordServlet")
public class ResetPasswordServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request, response);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//设置请求、响应编码格式request.setCharacterEncoding("UTF-8");response.setContentType("text/html;charset=UTF-8");//获取请求中的数据String username = request.getParameter("username");String password = request.getParameter("password");String newPassword = request.getParameter("newPassword");String role = request.getParameter("role");User user=null;try {//判断角色if ("student".equals(role)) {user= DBUtils.commonQueryObj(Student.class,"select * from student where username=? and password=?", username, password);} else if ("teacher".equals(role)) {user= DBUtils.commonQueryObj(Teacher.class,"select * from teacher where username=? and password=?", username, password);}if (user!=null){//修改if ("student".equals(role)){DBUtils.commonUpdate("update student set password=? where username=?",newPassword,username);} else if ("teacher".equals(role)) {DBUtils.commonUpdate("update teacher set password=? where username=?",newPassword,username);}//修改密码成功后，做安全退出的功能//修改密码了，相当于退出了request.getRequestDispatcher("SafeExitServlet").forward(request,response);}else {//修改密码失败--原密码不正确request.setAttribute("msg","修改密码失败--原密码不正确");request.getRequestDispatcher("resetPassword.jsp").forward(request,response);}} catch (SQLException e) {throw new RuntimeException(e);}}
}

10.修改学生信息（StuInitModifyServlet、StuModifyServlet）

index.jsp

不能直接跳转到修改信息页面，因为拿不到session数据，需要中间页面StuInitModifyServlet（页面跳页面获取学生信息）

在路径中传username，使StuInitModifyServlet可以拿到账号到数据库查询到改账号的学生信息

<h1>详情页面</h1><%if("student".equals(role)){%>
<!-- 在这个servlet通过username找到这个学生，再跳转到信息修改页面 -->
<a href="StuInitModifyServlet?username=<%=username%>">修改信息</a>
<%}%>

StuInitModifyServlet

操作：初始化修改学生数据

设置请求、响应编码格式
获取请求中的数据
从数据库中获取学生对象
将学生对象存在请求中，转发方式到学生修改信息页面stuInfo.jsp

package com.qf.Servlet;@WebServlet("/StuInitModifyServlet")
public class StuInitModifyServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request, response);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//设置请求、响应编码格式request.setCharacterEncoding("UTF-8");response.setContentType("text/html;charset=UTF-8");//获取请求中的数据String username = request.getParameter("username");//从数据库中获取学生对象Student student = null;try {student = DBUtils.commonQueryObj(Student.class, "select * from student where username=?", username);} catch (SQLException e) {throw new RuntimeException(e);}request.setAttribute("student",student);request.getRequestDispatcher("stuInfo.jsp").forward(request,response);}
}

stuInfo.jsp

对于没有学生信息，需要先到StuInitModifyServlet获取到学生对象，再获取其中信息，上传到stuInfo.jsp，用来修改页面展示和表单发送StuModifyServlet中的修改

注意：对性别和爱好的选择处理

<%@ page import="com.qf.pojo.Student" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>Title</title>
</head>
<body><%Student student = (Student) request.getAttribute("student");
%><h1>学生修改信息页面</h1><form action="StuModifyServlet" method="post"><input type="hidden" name="username" value="<%=student.getUsername()%>"/>账号：<%=student.getUsername()%><br/>姓名：<input type="text" name="name" value="<%=student.getName()%>"/><br/>年龄：<input type="text" name="age" value="<%=student.getAge()%>"/><br/>性别：<input type="radio" name="sex" value="man" <%=(student.getSex().equals("man"))?"checked='checked'":""%>/>男<input type="radio" name="sex" value="woman" <%=(student.getSex().equals("woman"))?"checked='checked'":""%>/>女<br/>爱好：<input type="checkbox" name="hobbies" value="football" <%=(student.getHobbies().contains("football"))?"checked='checked'":""%>/>足球<input type="checkbox" name="hobbies" value="basketball" <%=(student.getHobbies().contains("basketball"))?"checked='checked'":""%>/>篮球<input type="checkbox" name="hobbies" value="shop" <%=(student.getHobbies().contains("shop"))?"checked='checked'":""%>/>购物<br/><input type="submit" value="修改"/><input type="button" value="返回" οnclick="goIndex()"/>
</form><script type="text/javascript">function goIndex(){window.location = "index.jsp";}
</script>
</body>
</html>

优化：

主要是jsp的EL和JSTL表达式的改进

<%@ page import="com.qf.pojo.Student" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/functions" prefix="fn"%>
<html>
<head><title>Title</title>
</head>
<body><%--<%--%>
<%--    Student student = (Student) request.getAttribute("student");--%>
<%--%>--%><h1>学生修改信息页面</h1><form action="StuModifyServlet" method="post"><input type="hidden" name="username" value="${student.username}"/>账号：${student.username}<br/>姓名：<input type="text" name="name" value="${student.name}"/><br/>年龄：<input type="text" name="age" value="${student.age}"/><br/>性别：<input type="radio" name="sex" value="man" ${(student.sex eq 'man')?"checked='checked'":""}/>男<input type="radio" name="sex" value="woman" ${(student.sex eq 'woman')?"checked='checked'":""}/>女<br/>爱好：<input type="checkbox" name="hobbies" value="football" <c:if test="${fn:contains(student.hobbies, 'football')}">checked='checked'</c:if>/>足球<input type="checkbox" name="hobbies" value="basketball" <c:if test="${fn:contains(student.hobbies, 'basketball')}">checked='checked'</c:if>/>篮球<input type="checkbox" name="hobbies" value="shop" <c:if test="${fn:contains(student.hobbies, 'shop')}">checked='checked'</c:if>/>购物<br/><input type="submit" value="修改"/><input type="button" value="返回" οnclick="goIndex()"/>
</form><script type="text/javascript">function goIndex(){window.location = "index.jsp";}
</script>
</body>
</html>

StuModifyServlet（修改学生信息的逻辑）

1.设置请求、响应编码格式
2.获取请求中的数据
3.更新数据库里的学生数据
4.更新Session里的数据【原因：可能改名字，如果不改还是原来的名字就会在使用时出错】
5.更新Cookie里的数据【可存可不存，还是存一下，Cookie只有记住我才会有数据，name涉及凭证】
6.重定向方式跳转到详情页面index.jsp

package com.qf.Servlet;@WebServlet("/StuModifyServlet")
public class StuModifyServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request, response);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//设置请求、响应编码格式request.setCharacterEncoding("UTF-8");response.setContentType("text/html;charset=UTF-8");//获取请求中的数据String username = request.getParameter("username");String name = request.getParameter("name");String sex = request.getParameter("sex");String age = request.getParameter("age");String[] hobbies = request.getParameterValues("hobbies");//更新数据库里的学生数据try {DBUtils.commonUpdate("update student set name=?,sex=?,age=?,hobbies=? where username=?",name,sex,age, StringUtils.handleArray(hobbies),username);} catch (SQLException e) {throw new RuntimeException(e);}String role = (String) request.getSession().getAttribute("role");if("student".equals(role)){//更新Session里的数据request.getSession().setAttribute("name",name);//更新Cookie里的数据response.addCookie(CookieUtils.createCookie("name",name,60*60*24*5));//跳转详情页面response.sendRedirect("index.jsp");}else if("teacher".equals(role)){//跳转response.sendRedirect("GetStuListServlet?curPage=1");}}
}

11.修改老师信息（TeaInitModifyServlet、TeaModifyServlet）

详情页面 index.js

通过username拿到老师数据，交给request对象

<h1>详情页面</h1><%if("student".equals(role)){%>
<!-- 在这个servlet通过username找到这个学生，再跳转到信息修改页面 -->
<a href="StuInitModifyServlet?username=<%=username%>">修改信息</a>
<%}%>//省略

TeaInitModifyServle

操作：初始化修改老师数据

设置请求、响应编码格式
获取请求中的数据
从数据库中获取老师对象
将老师对象和课程集合对象存在请求中，转发方式到老师修改信息页面teaInfo.jsp

package com.qf.Servlet;@WebServlet("/TeaInitModifyServlet")
public class TeaInitModifyServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request, response);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//设置请求、响应编码格式request.setCharacterEncoding("UTF-8");response.setContentType("text/html;charset=UTF-8");//获取请求中的数据String username = request.getParameter("username");//从数据库中获取相应的数据Teacher teacher = null;List<Course> courses = null;try {teacher = DBUtils.commonQueryObj(Teacher.class,"select * from teacher where username=?",username);courses = DBUtils.commonQueryList(Course.class,"select * from course");} catch (SQLException e) {throw new RuntimeException(e);}//存入请求对象中request.setAttribute("teacher",teacher);request.setAttribute("courses",courses);//跳转页面request.getRequestDispatcher("teaInfo.jsp").forward(request,response);}
}

teaInfo.jsp（老师修改信息页面）

需要先到TeaInitModifyServlet获取到老师对象，再获取其中信息，用来修改页面展示和表单发送TeaModifyServlet中的修改

注意：对性别和学科选择的处理

对于学科考虑到会新增的情况，不能写死，通过获取学科集合再遍历的方式进行选择展示

<%@ page import="com.qf.pojo.Teacher" %>
<%@ page import="java.util.List" %>
<%@ page import="com.qf.pojo.Course" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>Title</title>
</head>
<body>
<%Teacher teacher = (Teacher) request.getAttribute("teacher");List<Course> courses = (List<Course>) request.getAttribute("courses");
%><h1>老师修改信息页面</h1><form action="TeaModifyServlet" method="post"><input type="hidden" name="username" value="<%=teacher.getUsername()%>"/>账号：<%=teacher.getUsername()%><br/>姓名：<input type="text" name="name" value="<%=teacher.getName()%>"/><br/>年龄：<input type="text" name="age" value="<%=teacher.getAge()%>"/><br/>性别：<input type="radio" name="sex" value="man" <%=(teacher.getSex().equals("man"))?"checked='checked'":""%>/>男<input type="radio" name="sex" value="woman" <%=(teacher.getSex().equals("woman"))?"checked='checked'":""%>/>女<br/>学科：<select><%for(Course course:courses){%><option value="<%=course.getId()%>" <%=(course.getId() == teacher.getCourseId())?"selected='selected'":""%> ><%=course.getName()%></option>
<%}%></select><br><input type="submit" value="修改"/><input type="button" value="返回" onclick="goIndex()"/>
</form><script type="text/javascript">function goIndex(){window.location = "index.jsp";}
</script>
</body>
</html>

优化：

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<%@ page import="com.qf.pojo.Course" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>Title</title>
</head>
<body>
<%--<%--%>
<%--    Teacher teacher = (Teacher) request.getAttribute("teacher");--%>
<%--    List<Course> courses = (List<Course>) request.getAttribute("courses");--%>
<%--%>--%><h1>老师修改信息页面</h1><form action="TeaModifyServlet" method="post"><input type="hidden" name="username" value="${teacher.username}"/>账号：${teacher.username}<br/>姓名：<input type="text" name="name" value="${teacher.name}"/><br/>年龄：<input type="text" name="age" value="${teacher.age}"/><br/>性别：<input type="radio" name="sex" value="man" ${(teacher.sex eq 'man')?"checked='checked'":""}/>男<input type="radio" name="sex" value="woman" ${(teacher.sex eq 'woman')?"checked='checked'":""}/>女<br/>学科：<select name="courseId"><c:forEach items="${courses}" var="course"><option value="${course.id}"  <c:if test="${course.id == teacher.courseId}">selected='selected'</c:if> >${course.name}</option></c:forEach></select><br/><input type="submit" value="修改"/><input type="button" value="返回" onclick="goIndex()"/>
</form><script type="text/javascript">function goIndex(){window.location = "index.jsp";}
</script>
</body>
</html>

TeaModifyServlet

设置请求、响应编码格式
获取请求中的数据
更新数据库里的老师数据
更新Session里的数据【原因：可能改名字，如果不改还是原来的名字就会在使用时出错】
更新Cookie里的数据【可存可不存，还是存一下，Cookie只有记住我才会有数据，name涉及凭证】
重定向方式跳转到详情页面index.jsp

package com.qf.Servlet;@WebServlet("/TeaModifyServlet")
public class TeaModifyServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request, response);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//设置请求、响应编码格式request.setCharacterEncoding("UTF-8");response.setContentType("text/html;charset=UTF-8");//获取请求中的数据String username = request.getParameter("username");String name = request.getParameter("name");String sex = request.getParameter("sex");String age = request.getParameter("age");String courseId = request.getParameter("courseId");//更新数据库里的学生数据try {DBUtils.commonUpdate("update teacher set name=?,sex=?,age=?,courseId=? where username=?",name,sex,age, courseId,username);} catch (SQLException e) {throw new RuntimeException(e);}//更新Session里的数据request.getSession().setAttribute("name",name);//更新Cookie里的数据response.addCookie(CookieUtils.createCookie("name",name,60*60*24*5));response.sendRedirect("index.jsp");}
}

12.老师角色查询所有学生

要用分页技术

在这里插入图片描述

index.jsp

不能直接跳stuList.jsp，没数据

TeaInitModifyServlet?username=<%=username%>：拼接一下，传数据

<h1>详情页面</h1><%if("teacher".equals(role)){%>
<a href="TeaInitModifyServlet?username=<%=username%>">修改信息</a>
<a href="GetStuListServlet?curPage=1">查看所有学生</a>
<%}%></script>
</body>
</html>

GetStuListServlet

拿数据和分页

package com.qf.Servlet;@WebServlet("/GetStuListServlet")
public class GetStuListServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request, response);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {request.setCharacterEncoding("UTF-8");response.setContentType("text/html;charset=UTF-8");//获取当前页数int curPage = Integer.parseInt(request.getParameter("curPage"));//设置当前页的数据条数int count = 15;//计算偏移量int offset = (curPage-1)*count;//计算总页数int totalPage;try {int allCount = DBUtils.getAllCount("student");if(allCount % count == 0){totalPage = allCount/count;}else{totalPage = allCount/count + 1;}} catch (SQLException e) {throw new RuntimeException(e);}//从数据库获取学生的集合List<Student> students = null;try {students = DBUtils.commonQueryList(Student.class, "select * from student limit ?,?", offset, count);} catch (SQLException e) {throw new RuntimeException(e);}//处理学生集合List<StudentDto> studentDtos = DtoUtils.studentDtoListHandler(students);//将数据存入到请求对象中request.setAttribute("curPage",curPage);request.setAttribute("totalPage",totalPage);request.setAttribute("studentDtos",studentDtos);//跳转request.getRequestDispatcher("stuList.jsp").forward(request,response);}
}

stuList.jsp，学生列表页面

添加学生信息处理后获取

<%@ page import="java.util.List" %>
<%@ page import="com.qf.pojo.Student" %>
<%@ page import="com.qf.dto.StudentDto" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>Title</title>
</head>
<body><%List<StudentDto> studentDtos = (List<StudentDto>) request.getAttribute("studentDtos");int curPage = (int) request.getAttribute("curPage");int totalPage = (int) request.getAttribute("totalPage");
%><button οnclick="doIndex()">返回</button>
<h1>学生列表页面</h1><table border="1" width="500px"><tr><th>账号</th><th>姓名</th><th>性别</th><th>年龄</th><th>爱好</th><th>操作</th></tr>//遍历，数据渲染<%for (StudentDto studentDto:studentDtos){%><tr><th><%=studentDto.getStudent().getUsername()%></th><th><%=studentDto.getStudent().getName()%></th><th><%=studentDto.getSex()%></th><th><%=studentDto.getStudent().getAge()%></th><th><%=studentDto.getHobbies()%></th><th><a href="StuInitModifyServlet?username=<%=studentDto.getStudent().getUsername()%>">修改</a><a href="StuDeleteServlet?username=<%=studentDto.getStudent().getUsername()%>">删除</a></th></tr><%}%>
</table>//分页
<a href="GetStuListServlet?curPage=1">首页</a>//第一页的时候不能有上一页
<%if(curPage > 1){%>
<a href="GetStuListServlet?curPage=<%=curPage-1%>">上一页</a>
<%}%>//最后一页的时候不能有下一页
<%if(curPage < totalPage){%>
<a href="GetStuListServlet?curPage=<%=curPage+1%>">下一页</a>
<%}%>
<a href="GetStuListServlet?curPage=<%=totalPage%>">尾页</a><script type="text/javascript">function goIndex(){window.location = "index.jsp";}
</script>
</body>
</html>

DBUtils 数据库工具类

获取当前表的总条数

    public static int getAllCount(String table) throws SQLException {Connection connection = getConnection();String sql = "select count(1) from " + table;PreparedStatement statement = connection.prepareStatement(sql);ResultSet resultSet = statement.executeQuery();if(resultSet.next()){int allCount = resultSet.getInt(1);return allCount;}return 0;}

Student

做分页的假数据

    public static void main(String[] args) {for (int i = 10; i < 100; i++) {String username = "xiaohei" + i;String password = "123123";String name = "小黑" + i;String sex = "man";int age = 23;String[] hobbies = {"football", "basketball"};try {DBUtils.commonUpdate("insert into student(username,password,name,sex,age,hobbies) values(?,?,?,?,?,?)", username, password, name, sex, age, StringUtils.handleArray(hobbies));} catch (SQLException e) {throw new RuntimeException(e);}}}

运行结果：

在这里插入图片描述

性别是man，爱好是英语，不方便观看，需要转成中文

包装学生类，写一个bto包，原来的student类不满足需求

分包新增信息处理类，以方便工具类对学生的信息处理

StudentDto

package com.qf.dto;public class StudentDto {private Student student;private String sex;private String hobbies;//无参构造，有参构造，get，set，toString类}

写一个工具类

DtoUtils

工具类，处理学生信息提升页面展示效果，然后在GetStuListServlet里操作

package com.qf.utils;public class DtoUtils {public static StudentDto studentDtoHandler(Student student) {//处理学生的性别数据String sex = student.getSex();if ("man".equals(sex)) {sex = "男";} else if ("woman".equals(sex)) {sex = "女";}//处理学生的爱好数据(做替换)String hobbies = student.getHobbies();hobbies = hobbies.replaceAll("football", "足球");hobbies = hobbies.replaceAll("basketball", "篮球");hobbies = hobbies.replaceAll("shop", "购物");//创建StudentDtoStudentDto studentDto = new StudentDto(student, sex, hobbies);return studentDto;}public static List<StudentDto> studentDtoListHandler(List<Student> students){ArrayList<StudentDto> studentDtos = new ArrayList<>();for (Student student:students){StudentDto studentDto = studentDtoHandler(student);studentDtos.add(studentDto);}return studentDtos;}
}

12.1 优化分页

GetStuListServlet

多了一个这个：设置URL：String url = “GetStuListServlet?curPage=”;

package com.qf.Servlet;@WebServlet("/GetStuListServlet")
public class GetStuListServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request, response);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {request.setCharacterEncoding("UTF-8");response.setContentType("text/html;charset=UTF-8");//获取当前页数int curPage = Integer.parseInt(request.getParameter("curPage"));//设置URLString url = "GetStuListServlet?curPage=";//设置当前页的数据条数int count = 15;//计算偏移量int offset = (curPage-1)*count;//计算总页数int totalPage;try {int allCount = DBUtils.getAllCount("student");if(allCount % count == 0){totalPage = allCount/count;}else{totalPage = allCount/count + 1;}} catch (SQLException e) {throw new RuntimeException(e);}//从数据库获取学生的集合List<Student> students = null;try {students = DBUtils.commonQueryList(Student.class, "select * from student limit ?,?", offset, count);} catch (SQLException e) {throw new RuntimeException(e);}//处理学生集合List<StudentDto> studentDtos = DtoUtils.studentDtoListHandler(students);//封装Page对象Page<StudentDto> page = new Page<>(url, curPage, totalPage, studentDtos);//将数据存入到请求对象中request.setAttribute("page",page);//跳转request.getRequestDispatcher("stuList.jsp").forward(request,response);}
}

上面的请求对象太多了，同一设置一个page类

原来是这个：

//将数据存入到请求对象中
request.setAttribute(“curPage”,curPage);
request.setAttribute(“totalPage”,totalPage);
request.setAttribute(“studentDtos”,studentDtos);

package com.qf.pojo;public class Page<T> {private String url;private int curPage;private int totalPage;private List<T> list;
//省略

page.jsp

把分页放在外面

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<a href="${page.url}1">首页</a>
<c:if test="${page.curPage > 1}"><a href="${page.url}${page.curPage-1}">上一页</a>
</c:if>
<c:if test="${page.curPage < page.totalPage}"><a href="${page.url}${page.curPage+1}">下一页</a>
</c:if>
<a href="${page.url}${page.totalPage}">尾页</a>

13.老师角色操作学生的修改

学生的修改写了的，就是StuInitModifyServlet

stuList.jsp

<%for (StudentDto studentDto:studentDtos){%><tr><th><%=studentDto.getStudent().getUsername()%></th><th><%=studentDto.getStudent().getName()%></th><th><%=studentDto.getSex()%></th><th><%=studentDto.getStudent().getAge()%></th><th><%=studentDto.getHobbies()%></th><th><a href="StuInitModifyServlet?username=<%=studentDto.getStudent().getUsername()%>">修改</a><a href="StuDeleteServlet?username=<%=studentDto.getStudent().getUsername()%>">删除</a></th></tr><%}%>

StuInitModifyServlet，跳转到StuModifyServlet

获取角色

1.通过角色判断修改

2.学生需要更新Session、Cookie里的数据，跳转详情页面

3.老师跳转GetStuListServlet，需要更新数据【因为修改了需要刷新页面】

（老师这里不需要修改cookie和session，最后一步不一样）

package com.qf.Servlet;@WebServlet("/StuModifyServlet")
public class StuModifyServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request, response);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//设置请求、响应编码格式request.setCharacterEncoding("UTF-8");response.setContentType("text/html;charset=UTF-8");//获取请求中的数据String username = request.getParameter("username");String name = request.getParameter("name");String sex = request.getParameter("sex");String age = request.getParameter("age");String[] hobbies = request.getParameterValues("hobbies");//更新数据库里的学生数据try {DBUtils.commonUpdate("update student set name=?,sex=?,age=?,hobbies=? where username=?",name,sex,age, StringUtils.handleArray(hobbies),username);} catch (SQLException e) {throw new RuntimeException(e);}String role = (String) request.getSession().getAttribute("role");if("student".equals(role)){//更新Session里的数据request.getSession().setAttribute("name",name);//更新Cookie里的数据response.addCookie(CookieUtils.createCookie("name",name,60*60*24*5));//跳转详情页面response.sendRedirect("index.jsp");}else if("teacher".equals(role)){//跳转response.sendRedirect("GetStuListServlet?curPage=1");}}
}

14.老师角色操作学生的删除

stuList.jsp

<h1>学生列表页面</h1><%for (StudentDto studentDto:studentDtos){%><tr><th><%=studentDto.getStudent().getUsername()%></th><th><%=studentDto.getStudent().getName()%></th><th><%=studentDto.getSex()%></th><th><%=studentDto.getStudent().getAge()%></th><th><%=studentDto.getHobbies()%></th><th><a href="StuInitModifyServlet?username=<%=studentDto.getStudent().getUsername()%>">修改</a><a href="StuDeleteServlet?username=<%=studentDto.getStudent().getUsername()%>">删除</a></th></tr><%}%>
</table></body>
</html>

StuDeleteServlet

设置编码格式，获取请求中的账号，通过学生账号删除学生，最后跳转GetStuListServlet同时更新数据

注意：实际开发项目中是不会直接用delete，而是改状态，数据库有提到

package com.qf.Servlet;@WebServlet("/StuDeleteServlet")
public class StuDeleteServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request, response);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {request.setCharacterEncoding("UTF-8");response.setContentType("text/html;charset=UTF-8");String username = request.getParameter("username");try {DBUtils.commonUpdate("delete from student where username=?",username);} catch (SQLException e) {throw new RuntimeException(e);}//跳转response.sendRedirect("GetStuListServlet?curPage=1");}
}