概念
WorkManager 是一个 API，可供您轻松调度那些即使在退出应用或重启设备后仍应运行的可延期异步任务。WorkManager API 是一个适合用来替换先前的 Android 后台调度 API（包括 FirebaseJobDispatcher、GcmNetworkManager 和 JobScheduler）的组件，我们也建议您这样做。WorkManager 在其现代、一致的 API 中整合了其前身的功能，该 API 支持 API 级别 14，在开发时即考虑到了对电池续航的影响。
原理
在后台，WorkManager 根据以下条件使用底层作业来调度服务：
build.gradle
dependencies {
def work_version = "2.5.0"
// (Java only)
implementation "androidx.work:work-runtime:$work_version"
// Kotlin + coroutines
implementation "androidx.work:work-runtime-ktx:$work_version"
// optional - RxJava2 support
implementation "androidx.work:work-rxjava2:$work_version"
// optional - GCMNetworkManager support
implementation "androidx.work:work-gcm:$work_version"
// optional - Test helpers
androidTestImplementation "androidx.work:work-testing:$work_version"
// optional - Multiprocess support
implementation "androidx.work:work-multiprocess:$work_version"
}
AndroidManifest.xml
<provider
android:name="androidx.work.impl.WorkManagerInitializer"
android:authorities="${applicationId}.workmanager-init"
tools:node="remove"
android:exported="false" />
Application
@Override
public void onCreate() {
super.onCreate();
Configuration configuration = new Configuration.Builder()
.setExecutor(Executors.newFixedThreadPool(8))
.build();
WorkManager.initialize(this, configuration);
}
Worker
public class UploadWorker extends Worker {
public UploadWorker(
@NonNull Context context,
@NonNull WorkerParameters params) {
super(context, params);
}
@Override
public Result doWork() {
// Do the work here--in this case, upload the images.
uploadImages();
// Indicate whether the work finished successfully with the Result
// Result.success()：工作成功完成。
// Result.failure()：工作失败。
// Result.retry()：工作失败，应根据其重试政策在其他时间尝试。
return Result.success();
}
}
WorkRequest
Constraints constraints = new Constraints.Builder()
.setRequiredNetworkType(NetworkType.CONNECTED)
.build();
OneTimeWorkRequest httpWorkRequest = new OneTimeWorkRequest.Builder(HttpWorker.class)
.setConstraints(constraints)
.setInitialDelay(2, TimeUnit.SECONDS)
.build();
将 WorkRequest 提交给系统
WorkManager
.getInstance(myContext)
.enqueue(uploadWorkRequest);
