抽取JDBC工具类

以下是一个简单的JDBC工具类的示例：

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class JDBCUtils {
    private static final String URL = "jdbc:mysql://localhost:3306/database_name";
    private static final String USERNAME = "username";
    private static final String PASSWORD = "password";

    public static Connection getConnection() {
        Connection connection = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            connection = DriverManager.getConnection(URL, USERNAME, PASSWORD);
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        }
        return connection;
    }

    public static void closeConnection(Connection connection, PreparedStatement preparedStatement, ResultSet resultSet) {
        try {
            if (resultSet != null) {
                resultSet.close();
            }
            if (preparedStatement != null) {
                preparedStatement.close();
            }
            if (connection != null) {
                connection.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

使用该工具类，您可以获取数据库连接和关闭连接。示例如下：

Connection connection = JDBCUtils.getConnection();
PreparedStatement preparedStatement = connection.prepareStatement("SELECT * FROM table_name");
ResultSet resultSet = preparedStatement.executeQuery();

while (resultSet.next()) {
    // 处理结果集
}

JDBCUtils.closeConnection(connection, preparedStatement, resultSet);

请注意，您需要将URL，USERNAME和PASSWORD替换为您自己的数据库连接信息