Erro NullPointerException

Não estou conseguindo conectar ao banco, quando vou realizar qualquer query ocorre o erro NullPointerException (linha 24 - ConnectionPool e 16 - TestaListagem

Segue abaixo as classes ConnectionPool e a classe TestaListagem:

package br.com.caelum.jdbc;

import java.sql.Connection;
import java.sql.SQLException;

import javax.sql.DataSource;

import com.mysql.jdbc.jdbc2.optional.MysqlConnectionPoolDataSource;

public class ConnectionPool {
    private DataSource dataSource;

    ConnectionPool() {

        MysqlConnectionPoolDataSource pool = new MysqlConnectionPoolDataSource();
        pool.setUrl("jdbc:mysql://localhost:3306/loja_virtual?useSSL=false");
        pool.setUser("root");
        pool.setPassword("123456");    
    }

    public Connection getConnection() throws SQLException {

        System.out.println("Abrindo conexão com o banco de dados");
        Connection connection = dataSource.getConnection();
        return connection;
    }

}

package br.com.caelum.jdbc;

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

public class TestaListagem {

    public static void main(String[] args) throws SQLException {
        ConnectionPool conexao= new ConnectionPool();
        try (Connection connection = conexao.getConnection()) {

            String sql = "select * from Produto";
            try (PreparedStatement statement = connection.prepareStatement(sql)) {
                boolean resultado = statement.execute();
                ResultSet resultSet = statement.getResultSet();

                while (resultSet.next()) {
                    int id = resultSet.getInt("id");
                    String nome = resultSet.getString("nome");
                    String descricao = resultSet.getString("descricao");
                    System.out.println("id=" + id + ", nome=" + nome + ", descricao=" + descricao);

                }
                resultSet.close();
            }

        }
    }
}