If you want to dynamically schedule tasks you can do it without spring by using ExecutorService in particular ScheduledThreadPoolExecutor
Runnable task = () -> doSomething();
ScheduledExecutorService executor = Executors.newScheduledThreadPool(Runtime.getRuntime().availableProcessors());
// Schedule a task that will be executed in 120 sec
executor.schedule(task, 120, TimeUnit.SECONDS);
// Schedule a task that will be first run in 120 sec and each 120sec
// If an exception occurs then it's task executions are canceled.
executor.scheduleAtFixedRate(task, 120, 120, TimeUnit.SECONDS);
// Schedule a task that will be first run in 120 sec and each 120sec after the last execution
// If an exception occurs then it's task executions are canceled.
executor.scheduleWithFixedDelay(task, 120, 120, TimeUnit.SECONDS);
With spring you can rely on the Task and Scheduling API
public class MyBean {
private final TaskScheduler executor;
@Autowired
public MyBean(TaskScheduler taskExecutor) {
this.executor = taskExecutor;
}
public void scheduling(final Runnable task) {
// Schedule a task to run once at the given date (here in 1minute)
executor.schedule(task, Date.from(LocalDateTime.now().plusMinutes(1)
.atZone(ZoneId.systemDefault()).toInstant()));
// Schedule a task that will run as soon as possible and every 1000ms
executor.scheduleAtFixedRate(task, 1000);
// Schedule a task that will first run at the given date and every 1000ms
executor.scheduleAtFixedRate(task, Date.from(LocalDateTime.now().plusMinutes(1)
.atZone(ZoneId.systemDefault()).toInstant()), 1000);
// Schedule a task that will run as soon as possible and every 1000ms after the previous completion
executor.scheduleWithFixedDelay(task, 1000);
// Schedule a task that will run as soon as possible and every 1000ms after the previous completion
executor.scheduleWithFixedDelay(task, Date.from(LocalDateTime.now().plusMinutes(1)
.atZone(ZoneId.systemDefault()).toInstant()), 1000);
// Schedule a task with the given cron expression
executor.schedule(task, new CronTrigger("*/5 * * * * MON-FRI"));
}
}
And you can provide your own trigger by implementing Trigger
Don't forget to enable the scheduling by usin @EnableScheduling on configuration class.
About listening to directory content you can use WatchService. Something like:
final Path myDir = Paths.get("my/directory/i/want/to/monitor");
final WatchService watchService = FileSystems.getDefault().newWatchService();
// listen to create event in the directory
myDir.register(watchService, StandardWatchEventKinds.ENTRY_CREATE);
// Infinite loop don't forget to run this in a Thread
for(;;) {
final WatchKey key = watchService.take();
for (WatchEvent<?> event : key.pollEvents()) {
WatchEvent<Path> watchEvent = (WatchEvent<Path>) event;
Path newFilePath = myDir.resolve(watchEvent.context());
//do something with the newFilePath
}
// To keep receiving event
key.reset();
}
Take a look at this article: Watching a Directory for Changes for more details.
