Planned lessonJNR-025-L01

From DriverManager to DataSource

Lesson 1 of 5
Junior

On This Lesson 4 topics

In this lesson
Planned topics
Draft outline details
Practice

This lesson is planned. The outline below lists the topics it will cover. The full lesson has not been published yet.

In this lesson

get database connections from a pool instead of opening one per statement.

Planned topics

JDBC is Java's standard API to talk to SQL databases; a driver (JAR) speaks the database's protocol.
DriverManager.getConnection(...) opens a brand-new connection each time: slow (network, login, setup).
A DataSource hands out connections; a pool (for example HikariCP) keeps them open and reuses them.
"Closing" a pooled connection returns it to the pool; always use try-with-resources.
Never open one connection per statement.

Draft outline details

Demonstration

java

try (Connection c = dataSource.getConnection();
     PreparedStatement ps = c.prepareStatement("select id, name from product where id = ?")) {
    ps.setLong(1, 42L);
    try (ResultSet rs = ps.executeQuery()) {
        if (rs.next()) System.out.println(rs.getString("name"));
    }
}

Check your understanding

What does close() do on a pooled connection?

Show answer

Returns it to the pool; the real connection stays open.

Practice

Apply this lesson with the module's lab, exercises and quiz.

Lab and exercises Quiz

Marking a lesson complete is optional and you can undo it any time. Your progress stays in this browser.

Continue to next lesson