How to add new schedule job dynamically with Spring

Question

I am writing a Spring Boot App

My requirements are - In the resources (src/main/resources) folder if I add new xml files.. I should read those files and get some ur

Answer 1

You can do that over a spring annotation:

@Scheduled(fixedRate = 360000)
public void parseXmlFile() {
    // logic for parsing the XML file.
}

Please note that the method must be void. Furthermore, in your main class, you must enable scheduling:

@SpringBootApplication
@EnableScheduling
public class Application {

    public static void main(String[] args) throws Exception {
        SpringApplication.run(Application.class);
    }
}

Please see the full reference here: https://spring.io/guides/gs/scheduling-tasks/

Answer 2

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.

Answer 3

Try this library with external dynamic parameters configuration, real time monitoring:

https://github.com/tyrion9/mtask

Config params in mtasks.yml

-   code: complex
    scheduled:
        period: 1000
    name: Autowired Param MTask
    className: sample.sample2.ComplexMTask
    params:
        name: HoaiPN
    autoStart: true

Dynamic params configurations on the fly:

curl -X GET http://localhost:8080/api

curl -X POST http://localhost:8080/api/helloworld/stop

curl -X POST http://localhost:8080/api/helloworld/start