泽西岛2.0:创建重复工作 [英] Jersey 2.0: Create repeating job

问题描述

在我们的REST服务中，我们想要实现一项工作，该工作每10秒检查一次.因此，我们认为可以使用Quartz来完成涵盖此任务的工作.但是问题是，我们需要注入一个单例，因为它是在作业中使用的，并且该作业似乎不在我们的服务上下文中，因此注入的类始终为null(NullPointerException).

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).

那么还有另一种可能的解决方案可以在不使用Quartz的情况下完成这项工作吗?已经尝试编写我们自己的JobFactory来将作业与BeanManager连接，但是它根本没有用.

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.

这是无法正常工作的代码:

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始终为空.

SharedMemory is always null.

推荐答案

我已经使用Scheduler上下文映射来实现此目的.你可以试试看.

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

在REST API中，当我们创建一个Scheduler时，我们可以使用上下文映射将参数传递给Job

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实施

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();
        }
    }

}

如果我的理解是错误的，请纠正我.

Correct me, if my understanding is wrong.

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