Jersey 2.0: Create repeating job

问题

In our REST-Service we want to implement a job that checks something every 10 seconds. So we thought we could use Quartz to make a Job that cover this. But the problem is, that we need to inject a singleton, because it is used in the job and the job seems to be not in the context of our service, so the injected class is always null (NullPointerException).

So is there another possible solution to achieve such a job without using Quartz? Already tried to write our own JobFactory that connects the job with the BeanManager, but it didnt work at all.

This is the code for the job that is not working:

@Stateless
public class GCEStatusJob  implements Job, Serializable{

    private Logger log = LoggerFactory.getLogger(GCEStatusJob.class);

    @Inject
    SharedMemory sharedMemory;

    @Override
    public void execute(JobExecutionContext jobExecutionContext) throws JobExecutionException {
        GoogleComputeEngineFactory googleComputeEngineFactory = new GoogleComputeEngineFactory();

        List<HeartbeatModel> heartbeatList = new ArrayList<>(sharedMemory.getAllHeartbeats());
        List<GCE> gceList = googleComputeEngineFactory.listGCEs();
        List<String> ipAddressList = gceList.stream().map(GCE::getIp).collect(Collectors.toList());

        for(HeartbeatModel heartbeat : heartbeatList){
            if(ipAddressList.contains(heartbeat.getIpAddress())){
                long systemTime = System.currentTimeMillis();

                if(systemTime-heartbeat.getSystemTime()>10000){
                    log.info("Compute Engine mit IP "+heartbeat.getIpAddress()+" antwortet nicht mehr. Wird neu gestartet!");
                    String name = gceList.stream().filter((i) -> i.getIp().equals(heartbeat.getIpAddress())).findFirst().get().getName();
                googleComputeEngineFactory.resetGCE(name);
                }
            }
        }
    }
}

SharedMemory is always null.

回答1:

I have used Scheduler context map to achive this. You can try this.

In REST API when we create a Scheduler we can use the Context map to pass the parameters to Job

@Path("job")
public class RESTApi {
    private String _userID;

    public String get_userID() {
        return _userID;
    }

    public void set_userID(String _userID) {
        this._userID = _userID;
    }
    @GET
    @Path("/start/{userId}")
    public void startJob(@PathParam("userId") String userID) {
        _userID = userID;
        try {
            SimpleTrigger trigger = new SimpleTrigger();
            trigger.setName("updateTrigger");
            trigger.setStartTime(new Date(System.currentTimeMillis() + 1000));
            trigger.setRepeatCount(SimpleTrigger.REPEAT_INDEFINITELY);
            trigger.setRepeatInterval(1000);
            JobDetail job = new JobDetail();
            job.setName("updateJob");
            job.setJobClass(GCEStatusJob.class);
            Scheduler scheduler = new StdSchedulerFactory().getScheduler();
            scheduler.getContext().put("apiClass", this);
            scheduler.start();
            scheduler.scheduleJob(job, trigger);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

JOB implementation

public class GCEStatusJob implements Job {
    @Override
    public void execute(JobExecutionContext arg0) throws JobExecutionException {
        RESTApi apiClass;
        try {
            apiClass = ((RESTApi) arg0.getScheduler().getContext().get("apiClass"));
            System.out.println("User name is" + apiClass.get_userID());
        } catch (SchedulerException e) {
            e.printStackTrace();
        }
    }

}

Correct me, if my understanding is wrong.

来源：https://stackoverflow.com/questions/30575591/jersey-2-0-create-repeating-job

标签

java

rest

jersey

quartz-scheduler