简单介绍：
这次的项目是用数据库实现学生的信息管理系统，有三步组成，写项目>>链接数据库>>实现相关的操作
开发工具：eclipse、MySQL、navicat、mysql-connector-java-8.0.27
1.数据库建表
-- 创建数据库CREATE DATABASE niitDEFAULT CHARACTER SET utf8mb4;SHOW DATABASES;-- 使用数据库niitUSE niit;-- 创建表StudentCREATE TABLE Student(ID INT PRIMARY KEY, NAME VARCHAR(4),GENDER CHAR(1),DOB DATE,BATCH INT);-- 插入记录INSERT INTO Student VALUES(1,'张','男','1988-1-2',1),(2,'李四','女','1988-12-3',1),(3,'王五','男','1978-11-1',1),(4,'若若','女','1989-2-5',2),(5,'夏春','女','1998-4-3',2),(6,'梅花','女','1999-12-6',2);-- 查看表中所有记录 语法：select * from 表名SELECT * FROM Student;
2，相关代码（主页面+增删查改）
（1）主页面
package studentManage;import java.awt.Color;import java.awt.EventQueue;import java.awt.Font;import javax.swing.JButton;import javax.swing.JFrame;import javax.swing.JLabel;import javax.swing.JPanel;import javax.swing.border.EmptyBorder;import java.awt.event.ActionListener;import java.awt.event.ActionEvent;public class MainFrame extends JFrame {private JPanel contentPane;/** * Launch the application. */// 有了main函数才可以单独运行public static void main(String[] args) {EventQueue.invokeLater(new Runnable() {public void run() {try {MainFrame frame = new MainFrame();frame.setVisible(true);} catch (Exception e) {e.printStackTrace();}}});}/** * Create the frame. */public MainFrame() {// 设置大小不可改变setResizable(false);// 设置标题setTitle("学生管理系统");// 由于这是主页面，所有当主页面关闭的时候，程序就直接退出setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);// setBounds(int x,int y,int width,int height);// x 和 y 是窗口打开时的位置// width 和 height 是窗口打宽度和高度setBounds(100, 100, 450, 350);// setLocationRelativeTo(c)// 设置窗口相对于 c 的位置，当 c 为空或者 null 时，默认为是相对于屏幕中央setLocationRelativeTo(null);// 实例化一个 panecontentPane = new JPanel();contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));setContentPane(contentPane);contentPane.setLayout(null);JLabel lblNewLabel = new JLabel("学生管理系统");lblNewLabel.setForeground(Color.RED);lblNewLabel.setFont(new Font("宋体", Font.BOLD, 25));lblNewLabel.setBounds(140, 10, 163, 44);contentPane.add(lblNewLabel);JButton addButton = new JButton("添加学生");// addActionListener 注册监听器addButton.addActionListener(new ActionListener() {public void actionPerformed(ActionEvent e) {// 设置新窗口可见new AddFrame().setVisible(true);}});addButton.setFont(new Font("宋体", Font.PLAIN, 18));addButton.setBounds(167, 64, 114, 37);contentPane.add(addButton);JButton changeButton = new JButton("修改信息");changeButton.addActionListener(new ActionListener() {public void actionPerformed(ActionEvent e) {// 同上new ChangeFrame().setVisible(true);}});changeButton.setFont(new Font("宋体", Font.PLAIN, 18));changeButton.setBounds(167, 121, 114, 37);contentPane.add(changeButton);JButton deleteButton = new JButton("删除学生");deleteButton.addActionListener(new ActionListener() {public void actionPerformed(ActionEvent e) {// 同上new DeleteFrame().setVisible(true);}});deleteButton.setFont(new Font("宋体", Font.PLAIN, 18));deleteButton.setBounds(167, 180, 114, 37);contentPane.add(deleteButton);JButton queryButton = new JButton("查询信息");queryButton.addActionListener(new ActionListener() {public void actionPerformed(ActionEvent e) {// 同上new QueryFrame().setVisible(true);}});queryButton.setFont(new Font("宋体", Font.PLAIN, 18));queryButton.setBounds(167, 240, 114, 37);contentPane.add(queryButton);}}
（2）添加界面
package studentManage;import java.awt.EventQueue;import java.awt.Font;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.sql.SQLException;import javax.swing.BoxLayout;import javax.swing.JButton;import javax.swing.JFrame;import javax.swing.JLabel;import javax.swing.JOptionPane;import javax.swing.JPanel;import javax.swing.JTextField;import javax.swing.border.EmptyBorder;public class AddFrame extends JFrame {private JPanel contentPane;private JTextField idField;private JTextField nameField;private JTextField genderField;private JTextField dobField;private JTextField batchField;/** * Launch the application. */public static void main(String[] args) {EventQueue.invokeLater(new Runnable() {public void run() {try {AddFrame frame = new AddFrame();frame.setVisible(true);} catch (Exception e) {e.printStackTrace();}}});}/** * Create the frame. */public AddFrame() {// 和前面类似setResizable(false);setTitle("添加学生");// 这个地方，添加学生只是这个程序的一部分，所以当关闭这部分的时候，程序不直接退出，只是关闭该部分程序setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);setBounds(100, 100, 450, 470);setLocationRelativeTo(null);contentPane = new JPanel();contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));setContentPane(contentPane);contentPane.setLayout(new BoxLayout(contentPane, BoxLayout.Y_AXIS));JPanel panel = new JPanel();contentPane.add(panel);panel.setLayout(null);JLabel TitleLabel = new JLabel("请输入新学生的信息：");TitleLabel.setFont(new Font("宋体", Font.BOLD, 20));TitleLabel.setBounds(71, 34, 220, 45);panel.add(TitleLabel);JLabel idLabel = new JLabel("学号：");idLabel.setFont(new Font("宋体", Font.PLAIN, 16));idLabel.setBounds(71, 105, 50, 30);panel.add(idLabel);idField = new JTextField();idField.setBounds(143, 99, 240, 45);panel.add(idField);idField.setColumns(10);JLabel nameLabel = new JLabel("姓名：");nameLabel.setFont(new Font("宋体", Font.PLAIN, 16));nameLabel.setBounds(71, 160, 50, 30);panel.add(nameLabel);nameField = new JTextField();nameField.setColumns(10);nameField.setBounds(143, 154, 240, 45);panel.add(nameField);JLabel genderLabel = new JLabel("性别：");genderLabel.setFont(new Font("宋体", Font.PLAIN, 16));genderLabel.setBounds(71, 215, 50, 30);panel.add(genderLabel);genderField = new JTextField();genderField.setColumns(10);genderField.setBounds(143, 209, 240, 45);panel.add(genderField);JLabel dobLabel = new JLabel("出生日期：");dobLabel.setFont(new Font("宋体", Font.PLAIN, 16));dobLabel.setBounds(41, 270, 80, 30);panel.add(dobLabel);dobField = new JTextField();dobField.setColumns(10);dobField.setBounds(143, 264, 240, 45);panel.add(dobField);JLabel batchLabel = new JLabel("班级：");batchLabel.setFont(new Font("宋体", Font.PLAIN, 16));batchLabel.setBounds(71, 325, 50, 30);panel.add(batchLabel);batchField = new JTextField();batchField.setColumns(10);batchField.setBounds(143, 319, 240, 45);panel.add(batchField);JButton addButton = new JButton("添加");// 添加鼠标监听事件addButton.addActionListener(new ActionListener() {public void actionPerformed(ActionEvent e) {// 先取出数据// getText() 返回字符串类型的// Integer.parseInt 数据类型转换int id = Integer.parseInt(idField.getText());String nameString = nameField.getText();String genderString = genderField.getText();String dobfieldString = dobField.getText();int batch = Integer.parseInt(batchField.getText());// 输出一下学生的信息，方便修改System.out.println(id + "\t" + nameString + "\t" + genderString + "\t" + dobfieldString + "\t" + batch);// SQLHelp 是自己写的一个工具类SQLHelp sqlHelp = new SQLHelp();try {// 调用添加学生信息的方法sqlHelp.addStudent(id, nameString, genderString, dobfieldString, batch);// 弹出对话框，提示用户添加成功JOptionPane.showMessageDialog(AddFrame.this, "添加成功！");} catch (SQLException e1) {// 这里捕获一下异常，因为学生的学号是唯一的，所以当学号已经存在的时候，提示用户，该学生信息已存在// 异常代码为 23000if(e1.getSQLState().equals("23000")) {JOptionPane.showMessageDialog(AddFrame.this, "添加失败!该学生已存在");}e1.printStackTrace();}}});addButton.setFont(new Font("宋体", Font.PLAIN, 18));addButton.setBounds(182, 389, 97, 33);panel.add(addButton);}}
（3）删除界面
package studentManage;import java.awt.EventQueue;import java.awt.Font;import javax.swing.BoxLayout;import javax.swing.JButton;import javax.swing.JFrame;import javax.swing.JLabel;import javax.swing.JOptionPane;import javax.swing.JPanel;import javax.swing.JTextField;import javax.swing.border.EmptyBorder;import java.awt.event.ActionListener;import java.sql.SQLException;import java.awt.event.ActionEvent;public class DeleteFrame extends JFrame {private JPanel contentPane;private JTextField idField;private JTextField nameField;private JTextField genderField;private JTextField dobField;private JTextField batchField;private JTextField searchField;/** * Launch the application. */public static void main(String[] args) {EventQueue.invokeLater(new Runnable() {public void run() {try {DeleteFrame frame = new DeleteFrame();frame.setVisible(true);} catch (Exception e) {e.printStackTrace();}}});}/** * Create the frame. */public DeleteFrame() {setResizable(false);setTitle("删除学生");setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);setBounds(100, 100, 450, 470);setLocationRelativeTo(null);contentPane = new JPanel();contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));setContentPane(contentPane);contentPane.setLayout(new BoxLayout(contentPane, BoxLayout.Y_AXIS));JPanel panel = new JPanel();contentPane.add(panel);panel.setLayout(null);JLabel lblNewLabel = new JLabel("请输入要删除的学生的学号：");lblNewLabel.setFont(new Font("宋体", Font.PLAIN, 16));lblNewLabel.setBounds(71, 0, 208, 29);panel.add(lblNewLabel);JLabel lblNewLabel_1 = new JLabel("学号：");lblNewLabel_1.setFont(new Font("宋体", Font.PLAIN, 16));lblNewLabel_1.setBounds(71, 105, 50, 30);panel.add(lblNewLabel_1);idField = new JTextField();idField.setEditable(false);idField.setBounds(143, 99, 240, 45);panel.add(idField);idField.setColumns(10);JLabel lblNewLabel_1_1 = new JLabel("姓名：");lblNewLabel_1_1.setFont(new Font("宋体", Font.PLAIN, 16));lblNewLabel_1_1.setBounds(71, 160, 50, 30);panel.add(lblNewLabel_1_1);nameField = new JTextField();nameField.setColumns(10);nameField.setBounds(143, 154, 240, 45);panel.add(nameField);JLabel lblNewLabel_1_1_1 = new JLabel("性别：");lblNewLabel_1_1_1.setFont(new Font("宋体", Font.PLAIN, 16));lblNewLabel_1_1_1.setBounds(71, 215, 50, 30);panel.add(lblNewLabel_1_1_1);genderField = new JTextField();genderField.setColumns(10);genderField.setBounds(143, 209, 240, 45);panel.add(genderField);JLabel lblNewLabel_1_1_1_1 = new JLabel("出生日期：");lblNewLabel_1_1_1_1.setFont(new Font("宋体", Font.PLAIN, 16));lblNewLabel_1_1_1_1.setBounds(41, 270, 80, 30);panel.add(lblNewLabel_1_1_1_1);dobField = new JTextField();dobField.setColumns(10);dobField.setBounds(143, 264, 240, 45);panel.add(dobField);JLabel lblNewLabel_1_1_1_2 = new JLabel("班级：");lblNewLabel_1_1_1_2.setFont(new Font("宋体", Font.PLAIN, 16));lblNewLabel_1_1_1_2.setBounds(71, 325, 50, 30);panel.add(lblNewLabel_1_1_1_2);batchField = new JTextField();batchField.setColumns(10);batchField.setBounds(143, 319, 240, 45);panel.add(batchField);JButton deleteButton = new JButton("删除");deleteButton.addActionListener(new ActionListener() {public void actionPerformed(ActionEvent e) {int id = Integer.parseInt(searchField.getText());try {SQLHelp sqlHelp = new SQLHelp();sqlHelp.deletestudent(id);JOptionPane.showMessageDialog(DeleteFrame.this, "删除成功！");} catch (SQLException e1) {JOptionPane.showMessageDialog(DeleteFrame.this, "删除失败");e1.printStackTrace();}}});deleteButton.setFont(new Font("宋体", Font.PLAIN, 18));deleteButton.setBounds(182, 389, 97, 33);panel.add(deleteButton);searchField = new JTextField();searchField.setBounds(71, 39, 208, 45);panel.add(searchField);searchField.setColumns(10);JButton searchButton = new JButton("查找");searchButton.addActionListener(new ActionListener() {public void actionPerformed(ActionEvent arg0) {int id = Integer.parseInt(searchField.getText());try {SQLHelp sqlHelp = new SQLHelp();Student student = sqlHelp.queryStudent(id);if(student != null) {idField.setText(String.valueOf(id));nameField.setText(student.getName());genderField.setText(student.getGender());dobField.setText(student.getDob());batchField.setText(String.valueOf(student.getBatch()));} else {JOptionPane.showMessageDialog(DeleteFrame.this, "无此学生");}} catch (SQLException e) {e.printStackTrace();}}});searchButton.setFont(new Font("宋体", Font.PLAIN, 18));searchButton.setBounds(289, 42, 97, 39);panel.add(searchButton);}}
（4）修改界面
package studentManage;import java.awt.EventQueue;import java.awt.Font;import javax.swing.BoxLayout;import javax.swing.JButton;import javax.swing.JFrame;import javax.swing.JLabel;import javax.swing.JOptionPane;import javax.swing.JPanel;import javax.swing.JTextField;import javax.swing.border.EmptyBorder;import java.awt.event.ActionListener;import java.sql.SQLException;import java.awt.event.ActionEvent;public class ChangeFrame extends JFrame {private JPanel contentPane;private JTextField idField;private JTextField nameField;private JTextField genderField;private JTextField dobField;private JTextField batchField;private JTextField searchField;/** * Launch the application. */public static void main(String[] args) {EventQueue.invokeLater(new Runnable() {public void run() {try {ChangeFrame frame = new ChangeFrame();frame.setVisible(true);} catch (Exception e) {e.printStackTrace();}}});}/** * Create the frame. */public ChangeFrame() {setResizable(false);setTitle("修改信息");setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);setBounds(100, 100, 450, 470);setLocationRelativeTo(null);contentPane = new JPanel();contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));setContentPane(contentPane);contentPane.setLayout(new BoxLayout(contentPane, BoxLayout.Y_AXIS));JPanel panel = new JPanel();contentPane.add(panel);panel.setLayout(null);JLabel lblNewLabel = new JLabel("请输入要修改的学生的学号：");lblNewLabel.setFont(new Font("宋体", Font.PLAIN, 16));lblNewLabel.setBounds(71, 0, 208, 29);panel.add(lblNewLabel);JLabel lblNewLabel_1 = new JLabel("学号：");lblNewLabel_1.setFont(new Font("宋体", Font.PLAIN, 16));lblNewLabel_1.setBounds(71, 105, 50, 30);panel.add(lblNewLabel_1);idField = new JTextField();idField.setEditable(false);idField.setBounds(143, 99, 240, 45);panel.add(idField);idField.setColumns(10);JLabel lblNewLabel_1_1 = new JLabel("姓名：");lblNewLabel_1_1.setFont(new Font("宋体", Font.PLAIN, 16));lblNewLabel_1_1.setBounds(71, 160, 50, 30);panel.add(lblNewLabel_1_1);nameField = new JTextField();nameField.setColumns(10);nameField.setBounds(143, 154, 240, 45);panel.add(nameField);JLabel lblNewLabel_1_1_1 = new JLabel("性别：");lblNewLabel_1_1_1.setFont(new Font("宋体", Font.PLAIN, 16));lblNewLabel_1_1_1.setBounds(71, 215, 50, 30);panel.add(lblNewLabel_1_1_1);genderField = new JTextField();genderField.setColumns(10);genderField.setBounds(143, 209, 240, 45);panel.add(genderField);JLabel lblNewLabel_1_1_1_1 = new JLabel("出生日期：");lblNewLabel_1_1_1_1.setFont(new Font("宋体", Font.PLAIN, 16));lblNewLabel_1_1_1_1.setBounds(41, 270, 80, 30);panel.add(lblNewLabel_1_1_1_1);dobField = new JTextField();dobField.setColumns(10);dobField.setBounds(143, 264, 240, 45);panel.add(dobField);JLabel lblNewLabel_1_1_1_2 = new JLabel("班级：");lblNewLabel_1_1_1_2.setFont(new Font("宋体", Font.PLAIN, 16));lblNewLabel_1_1_1_2.setBounds(71, 325, 50, 30);panel.add(lblNewLabel_1_1_1_2);batchField = new JTextField();batchField.setColumns(10);batchField.setBounds(143, 319, 240, 45);panel.add(batchField);JButton changeButton = new JButton("修改");changeButton.addActionListener(new ActionListener() {public void actionPerformed(ActionEvent arg0) {int id = Integer.parseInt(searchField.getText());String nameString = nameField.getText();String gendeString = genderField.getText();String dobString = dobField.getText();int batch = Integer.parseInt(batchField.getText());SQLHelp sqlHelp = new SQLHelp();try {sqlHelp.changeStudent(id, nameString, gendeString, dobString, batch);JOptionPane.showMessageDialog(ChangeFrame.this, "修改成功！");} catch (SQLException e) {JOptionPane.showMessageDialog(ChangeFrame.this, "修改失败！");e.printStackTrace();}}});changeButton.setFont(new Font("宋体", Font.PLAIN, 18));changeButton.setBounds(182, 389, 97, 33);panel.add(changeButton);searchField = new JTextField();searchField.setBounds(71, 39, 208, 45);panel.add(searchField);searchField.setColumns(10);JButton searchButton = new JButton("查找");searchButton.addActionListener(new ActionListener() {public void actionPerformed(ActionEvent e){int id = Integer.parseInt(searchField.getText());try {SQLHelp sqlHelp = new SQLHelp();Student student = sqlHelp.queryStudent(id);if(student != null) {// id 是直接读入的，所以就不需要从数据库中读出了idField.setText(String.valueOf(id));nameField.setText(student.getName());genderField.setText(student.getGender());dobField.setText(student.getDob());batchField.setText(String.valueOf(student.getBatch()));} else {JOptionPane.showMessageDialog(ChangeFrame.this, "无此用户");}} catch (SQLException e1) {e1.printStackTrace();}}});searchButton.setFont(new Font("宋体", Font.PLAIN, 18));searchButton.setBounds(289, 42, 97, 39);panel.add(searchButton);}}
（5）查找界面
package studentManage;import java.awt.EventQueue;import java.awt.Font;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.sql.SQLException;import javax.swing.BoxLayout;import javax.swing.JButton;import javax.swing.JFrame;import javax.swing.JLabel;import javax.swing.JOptionPane;import javax.swing.JPanel;import javax.swing.JTextField;import javax.swing.border.EmptyBorder;public class QueryFrame extends JFrame {private JPanel contentPane;private JTextField idField;private JTextField nameField;private JTextField genderField;private JTextField dobField;private JTextField batchField;private JTextField searchField;/** * Launch the application. */public static void main(String[] args) {EventQueue.invokeLater(new Runnable() {public void run() {try {QueryFrame frame = new QueryFrame();frame.setVisible(true);} catch (Exception e) {e.printStackTrace();}}});}/** * Create the frame. */public QueryFrame() {setResizable(false);setTitle("查询信息");setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);setBounds(100, 100, 450, 470);setLocationRelativeTo(null);contentPane = new JPanel();contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));setContentPane(contentPane);contentPane.setLayout(new BoxLayout(contentPane, BoxLayout.Y_AXIS));JPanel panel = new JPanel();contentPane.add(panel);panel.setLayout(null);JLabel lblNewLabel = new JLabel("请输入要查找的学生的学号：");lblNewLabel.setFont(new Font("宋体", Font.PLAIN, 16));lblNewLabel.setBounds(71, 0, 208, 29);panel.add(lblNewLabel);JLabel lblNewLabel_1 = new JLabel("学号：");lblNewLabel_1.setFont(new Font("宋体", Font.PLAIN, 16));lblNewLabel_1.setBounds(71, 105, 50, 30);panel.add(lblNewLabel_1);idField = new JTextField();idField.setEditable(false);idField.setBounds(143, 99, 240, 45);panel.add(idField);idField.setColumns(10);JLabel lblNewLabel_1_1 = new JLabel("姓名：");lblNewLabel_1_1.setFont(new Font("宋体", Font.PLAIN, 16));lblNewLabel_1_1.setBounds(71, 160, 50, 30);panel.add(lblNewLabel_1_1);nameField = new JTextField();nameField.setColumns(10);nameField.setBounds(143, 154, 240, 45);panel.add(nameField);JLabel lblNewLabel_1_1_1 = new JLabel("性别：");lblNewLabel_1_1_1.setFont(new Font("宋体", Font.PLAIN, 16));lblNewLabel_1_1_1.setBounds(71, 215, 50, 30);panel.add(lblNewLabel_1_1_1);genderField = new JTextField();genderField.setColumns(10);genderField.setBounds(143, 209, 240, 45);panel.add(genderField);JLabel lblNewLabel_1_1_1_1 = new JLabel("出生日期：");lblNewLabel_1_1_1_1.setFont(new Font("宋体", Font.PLAIN, 16));lblNewLabel_1_1_1_1.setBounds(41, 270, 80, 30);panel.add(lblNewLabel_1_1_1_1);dobField = new JTextField();dobField.setColumns(10);dobField.setBounds(143, 264, 240, 45);panel.add(dobField);JLabel lblNewLabel_1_1_1_2 = new JLabel("班级：");lblNewLabel_1_1_1_2.setFont(new Font("宋体", Font.PLAIN, 16));lblNewLabel_1_1_1_2.setBounds(71, 325, 50, 30);panel.add(lblNewLabel_1_1_1_2);batchField = new JTextField();batchField.setColumns(10);batchField.setBounds(143, 319, 240, 45);panel.add(batchField);searchField = new JTextField();searchField.setBounds(71, 39, 208, 45);panel.add(searchField);searchField.setColumns(10);JButton searchButton = new JButton("查找");searchButton.addActionListener(new ActionListener() {public void actionPerformed(ActionEvent arg0) {// 1.读出要查询的学生输入的id// 因为学生的学号是唯一的，所以我们根据学号查询后，只会有一条数据// 转化一下数据类型int id = Integer.parseInt(searchField.getText());// 2.执行JDBC语句try {SQLHelp sqlHelp = new SQLHelp();Student student = sqlHelp.queryStudent(id);// 3.将查询结果填到文本框中// 前提是学生存在if(student != null) {idField.setText(String.valueOf(id));nameField.setText(student.getName());genderField.setText(student.getGender());dobField.setText(student.getDob());batchField.setText(String.valueOf(student.getBatch()));} else {// 此时学生不存在，提示用户，不存在该学生JOptionPane.showMessageDialog(QueryFrame.this, "无此学生");}} catch (SQLException e) {e.printStackTrace();}}});searchButton.setFont(new Font("宋体", Font.PLAIN, 18));searchButton.setBounds(289, 42, 97, 39);panel.add(searchButton);}}
（6）数据库链接
package studentManage;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;publicclass SQLHelp {public static final String JDBC_DRIVER = "com.mysql.cj.jdbc.Driver";public static final String DB_URL = "jdbc:mysql://localhost:3306/niit?useSSL=false&allowPublicKeyRetrieval=true&serverTimezone=UTC";public static final String username = "root";public static final String password = "123456";private Connection connection = null;private PreparedStatement pStatement = null;private ResultSet rSet = null;// 加载驱动// 静态初始化块（只执行一次）static {try {Class.forName(JDBC_DRIVER);} catch (ClassNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();}}// 链接数据库public voidconnectDB() {try {connection = DriverManager.getConnection(DB_URL,username,password);System.out.println("数据库链接成功");} catch (SQLException e) {System.out.println("数据库链接失败");e.printStackTrace();}}// 关闭资源public void close() {if(rSet != null) {try {rSet.close();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}}if(pStatement != null) {try {pStatement.close();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}}if(connection != null) {try {connection.close();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}publicvoid addStudent(int id, String nameString, String genderString, String dobString, int batch) throws SQLException {// try finally 无论是否抛出异常都将执行 finally 中的语句try {// 先链接到数据库connectDB();// sql 语句// 静态 sql 语句需要进行字符串拼接// 动态 sql 语句String addsql = "insert into student values(?, ?, ?, ?, ?)";pStatement = connection.prepareStatement(addsql);pStatement.setInt(1, id);pStatement.setString(2, nameString);pStatement.setString(3, genderString);pStatement.setString(4, dobString);pStatement.setInt(5, batch);pStatement.executeUpdate();} finally {close();}}public void changeStudent(int id, String nameString, String genderString, String dobString, int batch) throws SQLException {try {connectDB();String changesql = "update student set name = ?, gender = ?, dob = ?, batch = ? where id = ?";pStatement = connection.prepareStatement(changesql);pStatement.setString(1, nameString);pStatement.setString(2, genderString);pStatement.setString(3, dobString);pStatement.setInt(4, batch);pStatement.setInt(5, id);pStatement.executeUpdate();} finally {close();}}public void deletestudent(int id) throws SQLException {try {connectDB();String deleteString = "select * from student where id = ?";pStatement = connection.prepareStatement(deleteString);pStatement.setInt(1, id);pStatement.execute();} finally {close();}}public Student queryStudent(int id) throws SQLException {try {connectDB();String querysql = "select * from student where id = ?";pStatement = connection.prepareStatement(querysql);pStatement.setInt(1, id);// 三种方法执行// execute()都可以使用，返回true或false// executeQuery() 专门用于查询，返回结果集// executeUpdate() 专门用于删除、更新rSet = pStatement.executeQuery();if(rSet.next()) {String nameString = rSet.getString(2);String genderString = rSet.getString(3);String dobString = rSet.getString(4);int batchString = rSet.getInt(5);// 查询到学生信息返回结果集return new Student(nameString, genderString, dobString, batchString);} else {// 没有查询到学生信息，返回nullreturn null;}} finally {close();}}}package studentManage;public class Student {private String name;private String gender;private String dob;private int batch;public Student(String name, String gender, String dob, int batch) {this.name = name;this.gender = gender;this.dob = dob;this.batch = batch;}public String getName() {return name;}public String getGender() {return gender;}public String getDob() {return dob;}public int getBatch() {return batch;}}package studentManage;import java.sql.*;public class JDBC{public static void main(String[] args) throws Exception {try {// 注册 JDBC 驱动Class.forName("com.mysql.cj.jdbc.Driver");// 打开链接Connection conn = DriverManager.getConnection("jdbc:conn-local://localhost:3306/text?useSSL=false&serverTimezone=UTC", "SQ", "109036");// 执行查询Statement stmt = conn.createStatement();String sql = "SELECT id, name, url FROM text";ResultSet rs = stmt.executeQuery(sql);// 展开结果集数据库while (rs.next()) {// 通过字段检索int id = rs.getInt("id");String name = rs.getString("name");String url = rs.getString("url");// 输出数据System.out.print("ID: " + id);System.out.print("NAME " + name);System.out.print("URL: " + url);System.out.print("\n");}// 释放资源rs.close();stmt.close();conn.close();} catch (ClassNotFoundException e) {e.printStackTrace();}}}添加Java驱动包，在官方网站下载mysql-connector-java-8.0.27，根据自己版本下载
