Scheduled tasks with Spring and Java configs

Spring 3.2 has some very nice features for scheduling tasks.

The pure Java way of doing this looks something like

private ScheduledExecutorService executor =
Executors.newSingleThreadScheduledExecutor();  
class ScheduledTask implements Runnable {  
    @Override  
    public void run() {  
        System.out.println("Running scheduled task");  
    }  
}

// Schedule a task every 5 seconds  
executor.scheduleAtFixedRate(new ScheduledTask(), 1, 5, TimeUnit.SECONDS);  
// If you don't do this then the JVM won't exit cleanly  
executor.shutdown();  

But now, with the snazzy new Spring scheduling annotations, it can be as simple as this

@Configuration  
@EnableScheduling  
public class MyAppConfig {  
    @Bean  
    public IHeartbeatService getHeartbeatService() {  
        return new HeartbeatServiceImpl();  
    }  
}

public class HeartbeatServiceImpl implements IHeartbeatService {  
    private static final String HEARTBEAT_DELAY_MS = "${heartbeat.initdelay.ms}";  
    private static final String HEARTBEAT_INIT_DELAY_MS = "${heartbeat.ms}";

    @Override  
    @Scheduled(initialDelayString = HEARTBEAT_DELAY_MS, fixedDelayString = HEARTBEAT_INIT_DELAY_MS)  
    public void sendHeartbeat() {  
        LOGGER.info("Heartbeating goes here.");  
    }  
}

The beauty of this approach is that

• It’s declarative.
• Spring’s property loading works.
• I don’t have to care about which Java executor Spring chooses under the hood.