Java에서 데이터베이스 연결 풀을 사용하여 데이터베이스 액세스 성능을 향상시키는 방법은 무엇입니까?

<dependency>
    <groupId>com.mchange</groupId>
    <artifactId>c3p0</artifactId>
    <version>0.9.5.2</version>
</dependency>

<?xml version="1.0" encoding="UTF-8"?>
<c3p0-config>
    <default-config>
        <property name="jdbcUrl">jdbc:mysql://localhost:3306/test</property>
        <property name="driverClass">com.mysql.jdbc.Driver</property>
        <property name="user">root</property>
        <property name="password">123456</property>
        <property name="initialPoolSize">5</property>
        <property name="maxPoolSize">20</property>
    </default-config>
</c3p0-config>

import com.mchange.v2.c3p0.ComboPooledDataSource;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class DatabaseUtil {
    private static ComboPooledDataSource dataSource;

    // 静态代码块，初始化数据库连接池
    static {
        dataSource = new ComboPooledDataSource();
        // 加载c3p0-config.xml配置文件
        dataSource.setConfigFile("c3p0-config.xml");
    }

    // 获取数据库连接
    public static Connection getConnection() throws SQLException {
        return dataSource.getConnection();
    }

    // 关闭数据库连接
    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();
        }
    }

    // 具体的数据库操作
    public static void queryUsers() {
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;
        try {
            connection = getConnection();
            String sql = "SELECT * FROM users";
            preparedStatement = connection.prepareStatement(sql);
            resultSet = preparedStatement.executeQuery();
            while (resultSet.next()) {
                System.out.println(resultSet.getString("name"));
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            closeConnection(connection, preparedStatement, resultSet);
        }
    }
}