android - 无法在 WorkManager 的 Worker 类中注入(inject)单例类

Question

我正在研究 MVVM 架构，我正在使用 Dagger2 进行数据注入(inject)。我面临的问题是，在 Activity/Fragments 中，@Inject 工作正常，但在 WorkManager 的 Worker 类中，@Inject 在运行时给出空指针异常。我该如何解决？

Worker类代码如下:

public class MySyncManager extends Worker {

    @Inject
    DataManager dataManager;

    @Inject
    SchedulerProvider schedulerProvider;

    @NonNull
    @Override
    public WorkerResult doWork() {

        CommonUtils.Log("usm_work_manager_1", "Work is Started.");
         if(dataManager==null) 
        CommonUtils.Log("usm_work_manager", "Injector is NULL");

    }
    }

方法:

    private void startTestSyncRequest() {
        Constraints myConstraints = new Constraints.Builder()
                .setRequiredNetworkType(NetworkType.CONNECTED)
                .build();
        OneTimeWorkRequest workRequest = new OneTimeWorkRequest.Builder(MySyncManager.class)
                .setConstraints(myConstraints)
                .setInitialDelay(1, TimeUnit.SECONDS)  // wait for n seconds before starting service
                .build();

        WorkManager.getInstance()
                .beginUniqueWork(Tags.TEST_WORK_NAME, ExistingWorkPolicy.REPLACE, workRequest)
                .enqueue();

}

Answer 1

在 worker 类中注入(inject)字段首先你需要在 AppComponent 中注入(inject)你的 worker 类:

 fun inject(syncItemWorker: SyncItemWorker)

然后在 worker 的 doWork() 中，你需要调用 inject:

 if(applicationContext is MyApp){
        var daggerAppComponent= DaggerAppComponent.builder().application(applicationContext as MyApp).build()
        daggerAppComponent.inject(this)
    }