简单学生管理系统
项目需求
数据库搭建
数据库建表
导数据库sql
了解
项目搭建
导包,基础页面,实体类,工具类
基础页面
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<h1>欢迎页面</h1>
<a href="login.html">登录</a>
<a href="register.html">注册</a>
</body>
</html>
实体类
public class User {
private String username;
private String password;
private String name;
private String sex;
private int age;
...
}
public class Student extends User{
private String hobbies;
...
}
public class Teacher extends User{
private int courseId;
...
}
public class Course {
private int id;
private String name;
...
}
工具类
/**
* 数据库工具类
*/
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, InstantiationException, IllegalAccessException {
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 = clazz.newInstance();
//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, InstantiationException, IllegalAccessException {
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 = clazz.newInstance();
//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;
}
/**
* 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();
}
}
}
}
功能实现
1.注册功能(简单实现)
注册的是学生,老师账号一般都由管理员分配
html页面
<body>
<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" onclick="goWelcome()"/>
</form>
<script type="text/javascript">
function goWelcome(){
window.location = "welcome.html";
}
</script>
</body>
RegisterServlet
- 设置请求、响应编码格式
- 获取请求中的数据
- 通过username查询数据库中的学生对象
- 通过学生对象进行判断
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
不允许注册,利用重定向跳转到注册页面
@WebServlet("/RegisterServlet")
public class RegisterServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
@Override
protected 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);
} catch (InstantiationException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
}
if(student == null){//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.html");
}else{//不允许注册
//利用重定向跳转到注册页面
response.sendRedirect("register.html");
}
}
}
新增工具类handleArray
处理数组,对于学生的爱好是数组
public class StringUtils {
public static String handleArray(Object[] os){
StringBuffer sb = new StringBuffer();
//利用反射实现
for (int i = 0; i<Array.getLength(os);i++){
if(i != 0){//不是第一次循环,也就是后面的循环才加逗号,注意先后顺序
sb.append(",");
}
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();
}
}
2.登录功能(只对账号、密码做了判断)
登录功能_账号密码角色
html页面
注意设置刷新验证码的函数
<body>
<h1>登录页面</h1>
<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" "><a href="#" ">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" onclick="goWelcome()"/>
</form>
<script type="text/javascript">
function goWelcome(){
window.location = "welcome.html";
}
</script>
</body>
<body>
<h1>详情页面</h1>
</body>
LoginServlet
- 设置请求、响应编码格式
- 获取请求中的数据
- 通过username、password查询数据库中的用户对象
- 通过用户对象进行判断
登录成功,利用重定向跳转到详情页面
登录失败 – 账号或密码错误,利用重定向跳转到登录页面
@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
@Override
protected 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");
//方法1
// String sysCode = CodeServlet.sysCode;
//完善的方法
//从Session对象中获取系统的验证码
String sysCode = (String) request.getSession().getAttribute("sysCode");
//equalsIgnoreCase不区分大小写比较
if(sysCode.equalsIgnoreCase(userCode)){//验证码正确
//通过username、password查询数据库中的用户对象
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(Student.class, "select * from teacher where username=? and password=?", username, password);
}
} catch (SQLException e) {
throw new RuntimeException(e);
}
if(user != null){//登录成功
//利用重定向跳转到详情页面
response.sendRedirect("index.html");
}else{//登录失败 -- 账号或密码错误
//利用重定向跳转到登录页面
response.sendRedirect("login.html");
}
}else{//登录失败 - 验证码错误
response.sendRedirect("login.html");
}
}
}
3.绘制验证码
登录验证码实现
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
@WebServlet("/CodeServlet")
public class CodeServlet extends HttpServlet {
//方法1:public static String sysCode;
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//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);
graphics.fillRect(0,0,width,height);
//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)];
Color randomColor = colors[random.nextInt(colors.length)];
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);
}
//方法1:sysCode = sb.toString();
//完善的方法
//将系统验证码设置到Session对象中(会话对象)
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());
//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.write(image,"jpg",response.getOutputStream());
}
}
4.完善验证码功能(Session-会话对象 )*
Session
简单理解
注意:浏览器不要禁用Cookie,JSESSIONID就不会保存
登录功能和绘制验证码的中描述未提及的内容
验证码:
方法1:
设置静态成员变量
public static String sysCode;
定义系统验证码
sysCode = sb.toString();
完善:
何时创建Session对象:要用到Session时才会创建
HttpSession session = request.getSession();
将系统验证码设置到Session对象中(会话对象)
session.setAttribute("sysCode",sb.toString());
ctrl+点击查看—底层:注意键和值分别的类型,Object意味着可以存对象
void setAttribute(String var1, Object var2);
添加登录验证码判断
方法1:
String sysCode = CodeServlet.sysCode;
共享变量验证码时登录情况
出现问题:当新开浏览器就会刷新验证码,就以前的验证码就用不了
没有对应的JESSIONID
完善:
从Session对象中获取系统的验证码,类型不一致注意强转
String sysCode = (String) request.getSession().getAttribute("sysCode");
equalsIgnoreCase不区分大小写比较系统验证码和用户验证码,包含了用户对象的判断,意味着登录验证先验证验证码
if(sysCode.equalsIgnoreCase(userCode)){ }else{}
获取Session对象解决问题
浏览器有cookie中存有对应的JESSIONID
修改register.html
添加刷新验证码的函数和绑定
验证码:<input type="text" name="userCode"/><img src="CodeServlet" width="120px" height="30px" onclick="refresh()"><a href="#" onclick="refresh()">刷新</a><br/>
<script type="text/javascript">
img = document.getElementsByTagName("img")[0];
function refresh(){
img.src = "CodeServlet?" + new Date();
}
</script>