Is My JDBC Connection Actually Using a Pool?

JDBC Connection Pooling: Verifying Implementation

Determining whether you're utilizing JDBC connection pooling can be confusing due to its purported simplicity. Let's delve into the provided connection class and usage to ascertain if true connection pooling is being employed.

Connection Class Analysis

The provided connection class appears to utilize DBCP's BasicDataSource for connection management. However, closer examination reveals that a new connection pool is being established on each connection acquisition. This negates the fundamental concept of connection pooling, as connections should be drawn from a single, shared pool.

Additionally, holding the connection as an instance variable is not recommended. Connections should be obtained on an as-needed basis and properly closed to reclaim resources effectively.

Rewritten Code Excerpts

To rectify these issues, here's a revised connection class:

public final class Database {

    private static final BasicDataSource dataSource = new BasicDataSource();

    static {
        dataSource.setDriverClassName("com.mysql.jdbc.Driver");
        dataSource.setUrl("jdbc:mysql://localhost:3306/data");
        dataSource.setUsername("USERNAME");
        dataSource.setPassword("PASSWORD");
    }

    private Database() {
        //
    }

    public static Connection getConnection() throws SQLException {
        return dataSource.getConnection();
    }

}

This code creates the connection pool once and provides a way to obtain connections from it.

Revised Connection Usage

Here's how you would use the connection class and JDBC functionality in a more robust manner:

private static final String SQL_EXIST = "SELECT * FROM users WHERE username=? AND password=?";

public boolean exist(User user) throws SQLException {
    boolean exist = false;

    try (
        Connection connection = Database.getConnection();
        PreparedStatement statement = connection.prepareStatement(SQL_EXIST);
    ) {
        statement.setString(1, user.getUsername());
        statement.setString(2, user.getPassword());

        try (ResultSet resultSet = preparedStatement.executeQuery()) {
            exist = resultSet.next();
        }
    }       

    return exist;
}

This revised code uses a try-with-resource block to ensure the proper release of connections and other resources.

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