java实验：数据库应用（idea+mysql+php)-编程知识

设计用户注册和登录界面，实现用户注册和登录操作。

设计用户注册/登录界面;
使用工具在MySQL中创建user表，包括学号、姓名、密码、专业、班级；
实现注册操作：在user表中插入一条新纪录，但学号不能重复；
实现登录操作：使用输入的学号和密码在user表中查找，查找成功，弹出消息框显示“登录成功”，不成功，则回到输入界面；使用对象文件记住在本机登录的用户名，显示在用户名组合框中。

一、首先去官网下载mysql。

这两个建议一起下，接着是配置环境，可以搜一下配置教程。

二、

启动如上图所示的mysql和apache服务。

三、

点击创建数据库。

根据提示填写，我这里的数据库名称是student,用户名ly，密码123456，最后点击确认。

接着转到mysql,

找到连接，点击mysql,会有一下窗户：

就依次按刚创建的数据库填写连接名，用户名，密码，其他不用改动，点击确定。

四、打开创建好的连接，新建表

点击保存。

继续保存，ctrl+s。

五、代码部分

代码是在idea中编写，首先要下载驱动文件mysql-connector-j-8.2.0.jar，mysql-connector-java下载_在下是小白的博客-CSDN博客

下载之后，把mysql-connector-j-8.2.0.jar复制到项目中

点击project structure,进入找到modules,点加号选第一个。

找到刚刚导入的mysql-connector-j-8.2.0.jar，双击点ok就可以了。

然后新建类粘贴一下代码：

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.*;public class UserRegistrationLogin extends JFrame {private JTextField studentIdField;private JPasswordField passwordField;private JTextField nameField;private JTextField majorField;private JTextField classField;private JComboBox<String> usernameComboBox;private Connection conn;public UserRegistrationLogin() {super("User Registration and Login");this.setDefaultCloseOperation(EXIT_ON_CLOSE);this.setSize(400, 300);this.setLocationRelativeTo(null);JPanel panel = new JPanel(new GridLayout(6, 2));JLabel studentIdLabel = new JLabel("Student ID:");studentIdField = new JTextField();JLabel passwordLabel = new JLabel("Password:");passwordField = new JPasswordField();JLabel nameLabel = new JLabel("Name:");nameField = new JTextField();JLabel majorLabel = new JLabel("Major:");majorField = new JTextField();JLabel classLabel = new JLabel("Class:");classField = new JTextField();JLabel usernameLabel = new JLabel("Username:");usernameComboBox = new JComboBox<>();JButton registerButton = new JButton("Register");JButton loginButton = new JButton("Login");panel.add(studentIdLabel);panel.add(studentIdField);panel.add(passwordLabel);panel.add(passwordField);panel.add(nameLabel);panel.add(nameField);panel.add(majorLabel);panel.add(majorField);panel.add(classLabel);panel.add(classField);panel.add(usernameLabel);panel.add(usernameComboBox);panel.add(registerButton);panel.add(loginButton);this.getContentPane().add(panel);registerButton.addActionListener(new ActionListener() {@Overridepublic void actionPerformed(ActionEvent e) {registerUser();}});loginButton.addActionListener(new ActionListener() {@Overridepublic void actionPerformed(ActionEvent e) {loginUser();}});try {String driver = "com.mysql.cj.jdbc.Driver";String url = "jdbc:mysql://localhost/student?user=ly&password=123456";Class.forName(driver);conn = DriverManager.getConnection(url);loadUsernames();} catch (ClassNotFoundException | SQLException ex) {ex.printStackTrace();}}private void registerUser() {String studentId = studentIdField.getText();String password = new String(passwordField.getPassword());String name = nameField.getText();String major = majorField.getText();String className = classField.getText();if (studentId.isEmpty() || password.isEmpty() || name.isEmpty() || major.isEmpty() || className.isEmpty()) {JOptionPane.showMessageDialog(this, "Please fill in all fields");return;}try {PreparedStatement stmt = conn.prepareStatement("INSERT INTO student (student_id, name, password, major, class) VALUES (?, ?, ?, ?, ?)");stmt.setString(1, studentId);stmt.setString(2, name);stmt.setString(3, password);stmt.setString(4, major);stmt.setString(5, className);stmt.executeUpdate();JOptionPane.showMessageDialog(this, "Registration successful");studentIdField.setText("");passwordField.setText("");nameField.setText("");majorField.setText("");classField.setText("");loadUsernames();} catch (SQLException ex) {JOptionPane.showMessageDialog(this, "Registration failed: " + ex.getMessage());}}private void loginUser() {String studentId = studentIdField.getText();String password = new String(passwordField.getPassword());try {PreparedStatement stmt = conn.prepareStatement("SELECT * FROM student WHERE student_id = ? AND password = ?");stmt.setString(1, studentId);stmt.setString(2, password);ResultSet rs = stmt.executeQuery();if (rs.next()) {String name = rs.getString("name");JOptionPane.showMessageDialog(this, "Login successful. Welcome, " + name + "!");// Remember the username for future loginsString selectedUsername = (String) usernameComboBox.getSelectedItem();if (selectedUsername == null || !selectedUsername.equals(name)) {usernameComboBox.addItem(name);usernameComboBox.setSelectedItem(name);}studentIdField.setText("");passwordField.setText("");} else {JOptionPane.showMessageDialog(this, "Login failed. Please check your student ID and password.");}} catch (SQLException ex) {JOptionPane.showMessageDialog(this, "Login failed: " + ex.getMessage());}}private void loadUsernames() {try {Statement stmt = conn.createStatement();ResultSet rs = stmt.executeQuery("SELECT DISTINCT name FROM student");usernameComboBox.removeAllItems();while (rs.next()) {String name = rs.getString("name");usernameComboBox.addItem(name);}} catch (SQLException ex) {ex.printStackTrace();}}public static void main(String[] args) {SwingUtilities.invokeLater(new Runnable() {@Overridepublic void run() {UserRegistrationLogin frame = new UserRegistrationLogin();frame.setVisible(true);}});}
}

效果展示：