Architecture -- WorkManager

1. WorkManager

1). 简介

其实就是"管理一些要在后台工作的任务, -- 即使你的应用没启动也能保证任务能被执行"，WorkManager在底层, 会根据你的设备情况, 选用JobScheduler, Firebase的JobDispatcher, 或是AlarmManager。WorkManager并不是为了那种在应用内的后台线程而设计出来的. 这种需求你应该使用ThreadPool。

2). 引入

• kolin

# Android Studio 3.0， 3.0以下版本请使用complie ext.work_version = "1.0.0-alpha02" // WorkManager implementation "android.arch.work:work-runtime:$work_version" // use -ktx for Kotlin // optional - Firebase JobDispatcher support implementation "android.arch.work:work-firebase:$work_version" // optional - Test helpers androidTestImplementation "android.arch.work:work-testing:$work_version" 

• java

# 必须加入 implementation "android.arch.work:work-runtime:1.0.0-alpha01" 

2. 用法

1). 执行一次的任务

• PullWorker.kt

/** * Pull 任务 * 创建步骤： * 1. 继承Worker类 * 2. 重写doWork()方法 * Created by mazaiting on 2018/6/6. */ class PullWorker : Worker() { override fun doWork(): WorkerResult { // 模拟设置页面中的"是否接受推送"是否被勾选 val isOkay = this.inputData.getBoolean("key_accept_bg_work", false) // 判断是否推送 if (isOkay) { // 模拟长时间工作 Thread.sleep(5000) // 获取数据 val pulledResult = startPull() // 设置输出数据 val output = Data.Builder().putString("key_pulled_result", pulledResult).build() // 存放数据 outputData = output // 返回成功 return WorkerResult.SUCCESS } else { // 返回失败 return WorkerResult.FAILURE } } /** * 开始推送 */ private fun startPull(): String { return "[worker] pull messages from backend." } } 

• PullEngine.kt

/** * Pull 引擎 * Created by mazaiting on 2018/6/6. */ class PullEngine { fun scheduleOneTimeWork(context: Context) { // 设置任务，执行一次 val pullRequest = OneTimeWorkRequestBuilder<PullWorker>() .setInputData( Data.Builder() .putBoolean("key_accept_bg_work", true) .build() ) .build() WorkManager.getInstance().enqueue(pullRequest) // 将请求入列 WorkManager.getInstance().enqueue(pullRequest) // 获取请求ID val pullRequestId = pullRequest.id // 存在SharedPreference中 PreferenceManager .getDefaultSharedPreferences(context) .edit() .putString("pullId", pullRequestId.toString()) .apply() } } 

• MainApplication.kt(注意在AndroidManifest.xml文件中配置)

class MainApplication : Application() { override fun onCreate() { super.onCreate() // 任务执行一次 PullEngine().scheduleOneTimeWork(this.applicationContext) } } 

• MainActivity.kt

class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) // UUID实现了Serializable接口，能由toString(),fromString()与String互转 val uuid = UUID.fromString( PreferenceManager.getDefaultSharedPreferences(this.applicationContext) .getString("pullId", "") ) WorkManager.getInstance() // 获取状态ID .getStatusById(uuid) // 观察数据 .observe(this, Observer<WorkStatus>{ status -> if (null != status && status.state.isFinished) { val pulledResult = status.outputData.getString("key_pulled_result","") Log.e("MainActivity", pulledResult) } }) } } 

• 打印结果

  
  
  图1.png

2). 任务设置约束

 fun scheduleOneTimeWork(context: Context) { val constraints = Constraints.Builder() // 负荷 .setRequiresCharging(true) .build() // 设置任务，执行一次 val pullRequest = OneTimeWorkRequestBuilder<PullWorker>() // 设置约束 .setConstraints(constraints) // 输入数据 .setInputData( Data.Builder() .putBoolean("key_accept_bg_work", true) .build() ) .build() // 将请求入列 WorkManager.getInstance().enqueue(pullRequest) // 获取请求ID val pullRequestId = pullRequest.id // 存在SharedPreference中 PreferenceManager .getDefaultSharedPreferences(context) .edit() .putString("pullId", pullRequestId.toString()) .apply() } 

3). 取消任务

 // 获取请求ID val pullRequestId = pullRequest.id // 取消任务 WorkManager.getInstance().cancelWorkById(pullRequestId) 

4). 任务链

WorkManager.getInstance() .beginWith(workA) // Note: WorkManager.beginWith() returns a // WorkContinuation object; the following calls are // to WorkContinuation methods .then(workB) // FYI, then() returns a new WorkContinuation instance .then(workC) .enqueue() 

或

WorkManager.getInstance() // First, run all the A tasks (in parallel): .beginWith(workA1, workA2, workA3) // ...when all A tasks are finished, run the single B task: .then(workB) // ...then run the C tasks (in any order): .then(workC1, workC2) .enqueue() 

再或

val chain1 = WorkManager.getInstance() .beginWith(workA) .then(workB) val chain2 = WorkManager.getInstance() .beginWith(workC) .then(workD) val chain3 = WorkContinuation .combine(chain1, chain2) .then(workE) chain3.enqueue() 

5). 定时任务

 /** * 执行任务 */ fun schedulePeriodicWork(context: Context) { val constraints = Constraints.Builder() // 负荷 .setRequiresCharging(true) .build() // 设置任务执行时长，并设置输入参数 // 长期任务，循环 val pullRequest = PeriodicWorkRequestBuilder<PullWorker>(30, TimeUnit.SECONDS) .setConstraints(constraints) .setInputData( Data.Builder() .putBoolean("key_accept_bg_work", true) .build() ) .build() // 将请求入列 WorkManager.getInstance().enqueue(pullRequest) // 获取请求ID val pullRequestId = pullRequest.id // 存在SharedPreference中 PreferenceManager .getDefaultSharedPreferences(context) .edit() .putString("pullId", pullRequestId.toString()) .apply() } 

6). 原文地址

7). 代码下载