Android WorkManager 指南 — 后台任务调度
WorkManager 能够在不同的 Android 版本中可靠地处理后台任务，同时尊重 Doze 模式和电池优化。
CoroutineWorker 基础
class MyCoroutineWorker(
context: Context,
params: WorkerParameters
) : CoroutineWorker(context, params) {
override suspend fun doWork(): Result {
return try {
val result = performBackgroundTask()
Result.success()
} catch (e: Exception) {
when {
e is IOException -> Result.retry()
else -> Result.failure()
}
}
}
private suspend fun performBackgroundTask(): String {
delay(2000)
return "Task completed"
}
}带约束条件的 WorkRequest
一次性工作请求：
val constraints = Constraints.Builder() .setRequiredNetworkType(NetworkType.CONNECTED) .setRequiresBatteryNotLow(true) .setRequiresDeviceIdle(false) .build() val workRequest = OneTimeWorkRequestBuilder<MyCoroutineWorker>() .setConstraints(constraints) .setBackoffCriteria( backoffPolicy = BackoffPolicy.EXPONENTIAL, initialDelay = 15, timeUnit = TimeUnit.MINUTES ) .build() WorkManager.getInstance(context).enqueueUniqueWork( "sync_work", ExistingWorkPolicy.KEEP, workRequest )
周期性工作请求
val periodicWorkRequest = PeriodicWorkRequestBuilder<MyCoroutineWorker>( 15, TimeUnit.MINUTES ).setConstraints(constraints).build() WorkManager.getInstance(context).enqueueUniquePeriodicWork( "periodic_sync", ExistingPeriodicWorkPolicy.KEEP, periodicWorkRequest )
输入/输出数据
val inputData = workDataOf(
"user_id" to 123,
"action" to "sync"
)
val workRequest = OneTimeWorkRequestBuilder<MyCoroutineWorker>()
.setInputData(inputData)
.build()
// 在 Worker 中
override suspend fun doWork(): Result {
val userId = inputData.getInt("user_id", -1)
val action = inputData.getString("action")
val outputData = workDataOf(
"result" to "success",
"timestamp" to System.currentTimeMillis()
)
return Result.success(outputData)
}WorkRequest 链式调用
顺序执行：
val uploadRequest = OneTimeWorkRequestBuilder<UploadWorker>().build() val syncRequest = OneTimeWorkRequestBuilder<SyncWorker>().build() val notifyRequest = OneTimeWorkRequestBuilder<NotifyWorker>().build() WorkManager.getInstance(context) .beginWith(uploadRequest) .then(syncRequest) .then(notifyRequest) .enqueue()
并行 + 顺序执行：
val task1 = OneTimeWorkRequestBuilder<Task1Worker>().build() val task2 = OneTimeWorkRequestBuilder<Task2Worker>().build() val merge = OneTimeWorkRequestBuilder<MergeWorker>().build() WorkManager.getInstance(context) .beginWith(listOf(task1, task2)) // 并行运行 .then(merge) // 然后合并结果 .enqueue()
在 Compose 中监控进度
@Composable
fun WorkProgressScreen() {
val workManager = WorkManager.getInstance(LocalContext.current)
val workState by workManager
.getWorkInfoByIdLiveData(workId)
.observeAsState()
Column(Modifier.fillMaxSize()) {
when {
workState?.state == WorkInfo.State.RUNNING -> {
val progress = workState?.progress?.getInt("progress", 0) ?: 0
LinearProgressIndicator(progress = progress / 100f)
Text("Progress: $progress%")
}
workState?.state == WorkInfo.State.SUCCEEDED -> {
Text("Task completed successfully")
}
workState?.state == WorkInfo.State.FAILED -> {
Text("Task failed")
}
}
}
}关键要点
使用 CoroutineWorker 处理挂起操作
设置约束条件以获得最佳执行条件
使用 beginWith/then 链式调用处理复杂工作流
通过 workDataOf 传递数据（JSON 可序列化类型）
在 UI 中使用 observeAsState 和 Compose 监控状态
为网络重试实现指数退避策略
