How are Spring <task:scheduled> objects represented at runtime?

Question

I have an app that uses the "task:scheduler" and "task:scheduled-tasks" elements (the latter containing "task:scheduled" elements). This is all working fine.

I'm trying to write some code that introspects the "application configuration" to get a short summary of some important information, like what tasks are scheduled and what their schedule is.

I already have a class that has a bunch of "@Autowired" instance variables so I can iterate through all of this. It was easy enough to add a "List" to get all of the TaskScheduler objects. I only have two of these, and I have a different set of scheduled tasks in each of them.

What I can't see in those TaskScheduler objects (they are actually ThreadPoolTaskScheduler objects) is anything that looks like a list of scheduled tasks, so I'm guessing the list of scheduled tasks is recorded somewhere else.

What objects can I use to introspect the set of scheduled tasks, and which thread pool they are in?

Answer 1

This functionality will be available in Spring 4.2

https://jira.spring.io/browse/SPR-12748 (Disclaimer: I reported this issue and contributed code towards its solution).

// Warning there may be more than one ScheduledTaskRegistrar in your
// application context. If this is the case you can autowire a list of 
// ScheduledTaskRegistrar instead.
@Autowired   
private ScheduledTaskRegistrar scheduledTaskRegistrar; 

public List<Task> getScheduledTasks() {
    List<Task> result = new ArrayList<Task>();
    result.addAll(this.scheduledTaskRegistrar.getTriggerTaskList());
    result.addAll(this.scheduledTaskRegistrar.getCronTaskList());
    result.addAll(this.scheduledTaskRegistrar.getFixedRateTaskList());
    result.addAll(this.scheduledTaskRegistrar.getFixedDelayTaskList());
    return result;
}

// You can this inspect the tasks, 
// so for example a cron task can be inspected like this:

public List<CronTask> getScheduledCronTasks() {
    List<CronTask> cronTaskList = this.scheduledTaskRegistrar.getCronTaskList();
    for (CronTask cronTask : cronTaskList) {
        System.out.println(cronTask.getExpression);
    }
    return cronTaskList;
}

If you are using a ScheduledMethodRunnable defined in XML:

<task:scheduled method="run" cron="0 0 12 * * ?" ref="MyObject" />

You can access the underlying target object:

 ScheduledMethodRunnable scheduledMethodRunnable = (ScheduledMethodRunnable) task.getRunnable();
 TargetClass target = (TargetClass) scheduledMethodRunnable.getTarget();