Java JDBC高封装Util类的项目实践

import java.sql.*;
​
public class JdbcUtil {
​
    private static final String URL = "jdbc:mysql://localhost:3306/database?serverTimezone=UTC&useSSL=false";
    private static final String USERNAME = "username";
    private static final String PASSWORD = "password";
​
    private static Connection connection = null;
​
    static {
        try {
            connection = DriverManager.getConnection(URL, USERNAME, PASSWORD);
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
​
    public static PreparedStatement getPreparedStatement(String sql, Object... args) throws SQLException {
        PreparedStatement preparedStatement = connection.prepareStatement(sql);
        for (int i = 0; i < args.length; i++) {
            preparedStatement.setObject(i + 1, args[i]);
        }
        return preparedStatement;
    }
​
    public static ResultSet executeQuery(String sql, Object... args) throws SQLException {
        PreparedStatement preparedStatement = getPreparedStatement(sql, args);
        return preparedStatement.executeQuery();
    }
​
    public static int executeUpdate(String sql, Object... args) throws SQLException {
        PreparedStatement preparedStatement = getPreparedStatement(sql, args);
        return preparedStatement.executeUpdate();
    }
​
    public static void close() {
        try {
            if (connection != null && !connection.isClosed()) {
                connection.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

import java.sql.*;
​
public class Main {
    public static void main(String[] args) {
        try {
            String sql = "SELECT name FROM users";
            ResultSet resultSet = JdbcUtil.executeQuery(sql);
            while (resultSet.next()) {
                String name = resultSet.getString("name");
                System.out.println(name);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JdbcUtil.close();
        }
    }
}

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Vector;
import javax.swing.JTable;
import javax.swing.table.DefaultTableModel;
import java.awt.Dimension;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
​
public class Main {
​
    public static void main(String[] args) {
        try {
            // 执行查询语句
            String sql = "SELECT * FROM users";
            ResultSet resultSet = JdbcUtil.executeQuery(sql);
​
            // 将查询结果封装为Vector数据结构
            Vector<String> columnNames = new Vector<>();
            columnNames.add("id");
            columnNames.add("name");
            columnNames.add("age");
​
            Vector<Vector<Object>> data = new Vector<>();
            while (resultSet.next()) {
                Vector<Object> row = new Vector<>();
                row.add(resultSet.getInt("id"));
                row.add(resultSet.getString("name"));
                row.add(resultSet.getInt("age"));
                data.add(row);
            }
​
            // 创建表格，并设置数据
            DefaultTableModel model = new DefaultTableModel(data, columnNames);
            JTable table = new JTable(model);
​
            // 将表格放置到窗口中
            JFrame frame = new JFrame();
            frame.getContentPane().add(new JScrollPane(table));
            frame.setPreferredSize(new Dimension(500, 300));
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.pack();
            frame.setVisible(true);
​
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JdbcUtil.close();
        }
    }
}