• PageKeyedDataSource ：适用于目标数据根据页信息请求数据的场景，即Key 字段是页相关的信息。比如请求的数据的参数中包含类似next/previous的信息。
• ItemKeyedDataSource ：适用于目标数据的加载依赖特定item的信息， 即Key字段包含的是Item中的信息，比如需要根据第N项的信息加载第N+1项的数据，传参中需要传入第N项的ID时，该场景多出现于论坛类应用评论信息的请求。
• PositionalDataSource：适用于目标数据总数固定，通过特定的位置加载数据，这里Key是Integer类型的位置信息，T即Value。 比如从数据库中的1200条开始加在20条数据。

• mMainThreadExecutor: 主线程的Excutor, 用于将结果post到主线程。
  
• mBackgroundThreadExecutor: 后台线程的Excutor.
  
• BoundaryCallback:加载Datasource中的数据加载到边界时的回调.
  
• Config: 配置PagedList从Datasource加载数据的方式， 其中包含以下属性：
  
  • pageSize：设置每页加载的数量
  • prefetchDistance：预加载的数量
  • initialLoadSizeHint：初始化数据时加载的数量
  • enablePlaceholders：当item为null是否使用PlaceHolder展示
  • PagedStorage: 用于存储加载到的数据，它是真正的蓄水池所在，它包 含一个ArrayList> 对象mPages，按页存储数据。

def paging_version = "1.0.0" def lifecycle_version = "1.1.1" def room_version = "1.1.0" //这是 Paging的依赖 implementation "android.arch.paging:runtime:$paging_version" // alternatively - without Android dependencies for testing testImplementation "android.arch.paging:common:$paging_version" // optional - RxJava support, currently in release candidate implementation 'android.arch.paging:rxjava2:1.0.0-rc1'//这是ViewModel and LiveData 的依赖 implementation "android.arch.lifecycle:extensions:$lifecycle_version"implementation "android.arch.persistence.room:runtime:$room_version" //这是room的依赖 implementation "android.arch.persistence.room:rxjava2:$room_version" // optional - Guava support for Room, including Optional and ListenableFuture implementation "android.arch.persistence.room:guava:$room_version" // Test helpers testImplementation "android.arch.persistence.room:testing:$room_version"

//java用这个 // annotationProcessor "android.arch.persistence.room:compiler:$room_version" //kotlin 用这个 kapt 'android.arch.persistence.room:compiler:1.0.0'

@Entity data class Student(@PrimaryKey(autoGenerate = true) val id: Int, val name: String)

@Dao interface StudentDao { /** * Room knows how to return a LivePagedListProvider, from which we can get a LiveData and serve * it back to UI via ViewModel. */ @Query("SELECT * FROM Student ORDER BY name COLLATE NOCASE ASC") fun allStudentByName(): DataSource.Factory@Insert fun insert(student: List)@Insert fun insert(student: Student)@Delete fun delete(student: Student) }

private val IO_EXECUTOR = Executors.newSingleThreadExecutor()/** * Utility method to run blocks on a dedicated background thread, used for io/database work. */ fun ioThread(f : () -> Unit) { IO_EXECUTOR.execute(f) }

@Database(entities = arrayOf(Student::class), version = 1) abstract class StudentDb : RoomDatabase() { abstract fun studentDao(): StudentDao override fun clearAllTables() {} companion object { private var instance: StudentDb? = null @Synchronized fun get(context: Context): StudentDb { if (instance == null) { instance = Room.databaseBuilder(context.applicationContext, StudentDb::class.java, "student.db") .addCallback(object : RoomDatabase.Callback() { override fun onCreate(db: SupportSQLiteDatabase) { fillInDb(context.applicationContext) } }).build() } return instance!! }/** * fill database with list of cheeses */ private fun fillInDb(context: Context) { // 在Room中的插入是在当前线程上执行的，因此我们将插入到后台线程中 ioThread { get(context).studentDao().insert( CHEESE_DATA.map { Student(id = 0, name = it) }) } }} }private val CHEESE_DATA = https://www.it610.com/article/arrayListOf("Abbaye de Belloc", "Abbaye du Mont des Cats", "Abertam", "Abondance", "Ackawi", "Acorn", "Adelost", "Affidelice au Chablis", "Afuega'l Pitu", "Airag", "Airedale", "Aisy Cendre", "Allgauer Emmentaler", "Alverca", "Ambert", "American Student", "Ami du Chambertin", "Anejo Enchilado", "Anneau du Vic-Bilh", "Anthoriro", "Appenzell", "Aragon", "Ardi Gasna", "Ardrahan", "Armenian String", "Aromes au Gene de Marc", "Asadero", "Asiago", "Aubisque Pyrenees", "Autun", "Avaxtskyr", "Baby Swiss", "Babybel", "Baguette Laonnaise", "Bakers", "Baladi", "Balaton", "Bandal", "Banon", "Barry's Bay Cheddar", "Basing", "Basket Student", "Bath Student", "Bavarian Bergkase", "Baylough", "Beaufort", "Beauvoorde", "Beenleigh Blue", "Beer Student", "Bel Paese", "Bergader", "Bergere Bleue", "Berkswell", "Beyaz Peynir", "Bierkase", "Bishop Kennedy", "Blarney", "Bleu d'Auvergne", "Bleu de Gex", "Bleu de Laqueuille", "Bleu de Septmoncel", "Bleu Des Causses", "Blue", "Blue Castello", "Blue Rathgore", "Blue Vein (Australian)", "Blue Vein Cheeses", "Bocconcini", "Bocconcini (Australian)", "Boeren Leidenkaas", "Bonchester", "Bosworth", "Bougon", "Boule Du Roves", "Boulette d'Avesnes", "Boursault", "Boursin", "Bouyssou", "Bra", "Braudostur", "Breakfast Student", "Brebis du Lavort", "Brebis du Lochois", "Brebis du Puyfaucon", "Bresse Bleu", "Brick", "Brie", "Brie de Meaux", "Brie de Melun", "Brillat-Savarin", "Brin", "Brin d' Amour", "Brin d'Amour", "Brinza (Burduf Brinza)", "Briquette de Brebis", "Briquette du Forez", "Broccio", "Broccio Demi-Affine", "Brousse du Rove", "Bruder Basil", "Brusselae Kaas (Fromage de Bruxelles)", "Bryndza", "Buchette d'Anjou", "Buffalo", "Burgos", "Butte", "Butterkase", "Button (Innes)", "Buxton Blue", "Cabecou", "Caboc", "Cabrales", "Cachaille", "Caciocavallo", "Caciotta", "Caerphilly", "Cairnsmore", "Calenzana", "Cambazola", "Camembert de Normandie", "Canadian Cheddar", "Canestrato", "Cantal", "Caprice des Dieux", "Capricorn Goat", "Capriole Banon", "Carre de l'Est", "Casciotta di Urbino", "Cashel Blue", "Castellano", "Castelleno", "Castelmagno", "Castelo Branco", "Castigliano", "Cathelain", "Celtic Promise", "Cendre d'Olivet", "Cerney", "Chabichou", "Chabichou du Poitou", "Chabis de Gatine", "Chaource", "Charolais", "Chaumes", "Cheddar", "Cheddar Clothbound", "Cheshire", "Chevres", "Chevrotin des Aravis", "Chontaleno", "Civray", "Coeur de Camembert au Calvados", "Coeur de Chevre", "Colby", "Cold Pack", "Comte", "Coolea", "Cooleney", "Coquetdale", "Corleggy", "Cornish Pepper", "Cotherstone", "Cotija", "Cottage Student", "Cottage Student (Australian)", "Cougar Gold", "Coulommiers", "Coverdale", "Crayeux de Roncq", "Cream Student", "Cream Havarti", "Crema Agria", "Crema Mexicana", "Creme Fraiche", "Crescenza", "Croghan", "Crottin de Chavignol", "Crottin du Chavignol", "Crowdie", "Crowley", "Cuajada", "Curd", "Cure Nantais", "Curworthy", "Cwmtawe Pecorino", "Cypress Grove Chevre", "Danablu (Danish Blue)", "Danbo", "Danish Fontina", "Daralagjazsky", "Dauphin", "Delice des Fiouves", "Denhany Dorset Drum", "Derby", "Dessertnyj Belyj", "Devon Blue", "Devon Garland", "Dolcelatte", "Doolin", "Doppelrhamstufel", "Dorset Blue Vinney", "Double Gloucester", "Double Worcester", "Dreux a la Feuille", "Dry Jack", "Duddleswell", "Dunbarra", "Dunlop", "Dunsyre Blue", "Duroblando", "Durrus", "Dutch Mimolette (Commissiekaas)", "Edam", "Edelpilz", "Emental Grand Cru", "Emlett", "Emmental", "Epoisses de Bourgogne", "Esbareich", "Esrom", "Etorki", "Evansdale Farmhouse Brie", "Evora De L'Alentejo", "Exmoor Blue", "Explorateur", "Feta", "Feta (Australian)", "Figue", "Filetta", "Fin-de-Siecle", "Finlandia Swiss", "Finn", "Fiore Sardo", "Fleur du Maquis", "Flor de Guia", "Flower Marie", "Folded", "Folded cheese with mint", "Fondant de Brebis", "Fontainebleau", "Fontal", "Fontina Val d'Aosta", "Formaggio di capra", "Fougerus", "Four Herb Gouda", "Fourme d' Ambert", "Fourme de Haute Loire", "Fourme de Montbrison", "Fresh Jack", "Fresh Mozzarella", "Fresh Ricotta", "Fresh Truffles", "Fribourgeois", "Friesekaas", "Friesian", "Friesla", "Frinault", "Fromage a Raclette", "Fromage Corse", "Fromage de Montagne de Savoie", "Fromage Frais", "Fruit Cream Student", "Frying Student", "Fynbo", "Gabriel", "Galette du Paludier", "Galette Lyonnaise", "Galloway Goat's Milk Gems", "Gammelost", "Gaperon a l'Ail", "Garrotxa", "Gastanberra", "Geitost", "Gippsland Blue", "Gjetost", "Gloucester", "Golden Cross", "Gorgonzola", "Gornyaltajski", "Gospel Green", "Gouda", "Goutu", "Gowrie", "Grabetto", "Graddost", "Grafton Village Cheddar", "Grana", "Grana Padano", "Grand Vatel", "Grataron d' Areches", "Gratte-Paille", "Graviera", "Greuilh", "Greve", "Gris de Lille", "Gruyere", "Gubbeen", "Guerbigny", "Halloumi", "Halloumy (Australian)", "Haloumi-Style Student", "Harbourne Blue", "Havarti", "Picodon de Chevre", "Picos de Europa", "Piora", "Pithtviers au Foin", "Plateau de Herve", "Plymouth Student", "Podhalanski", "Poivre d'Ane", "Polkolbin", "Pont l'Eveque", "Port Nicholson", "Port-Salut", "Postel", "Pouligny-Saint-Pierre", "Pourly", "Prastost", "Pressato", "Prince-Jean", "Processed Cheddar", "Provolone", "Stilton", "Stinking Bishop", "String", "Sussex Slipcote", "Sveciaost", "Swaledale", "Sweet Style Swiss", "Swiss", "Syrian (Armenian String)", "Tala", "Taleggio", "Tamie", "Tasmania Highland Chevre Log", "Taupiniere", "Teifi", "Telemea", "Testouri", "Tete de Moine", "Tetilla", "Texas Goat Student", "Tibet", "Tillamook Cheddar", "Zamorano", "Zanetti Grana Padano", "Zanetti Parmigiano Reggiano");

class StudentAdapter : PagedListAdapter(diffCallback) { override fun onBindViewHolder(holder: StudentViewHolder, position: Int) { holder.bindTo(getItem(position)) }override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): StudentViewHolder = StudentViewHolder(parent)companion object { /** * 这个diff回调通知PagedListAdapter在新列表到来的时候如何计算列表差异 * * 当您使用“add”按钮添加一个Student的时候，PagedListAdapter使用diffCallback t去检测到与以前的Item的不同，所以它只需要重画和重新绑定一个视图。 * * @see android.support.v7.util.DiffUtil */ private val diffCallback = object : DiffUtil.ItemCallback() { override fun areItemsTheSame(oldItem: Student, newItem: Student): Boolean = oldItem.id == newItem.id/** * 注意 kotlin的== 等价于java的equas()方法 */ override fun areContentsTheSame(oldItem: Student, newItem: Student): Boolean = oldItem == newItem } } }

class StudentViewHolder(parent :ViewGroup) : RecyclerView.ViewHolder( LayoutInflater.from(parent.context).inflate(R.layout.student_item, parent, false)) {private val nameView = itemView.findViewById(R.id.name) var student : Student? = null/** * Items might be null if they are not paged in yet. PagedListAdapter will re-bind the * ViewHolder when Item is loaded. */ fun bindTo(student : Student?) { this.student = student nameView.text = student?.name } }

class StudentiewModel(app: Application) : AndroidViewModel(app) { val dao = StudentDb.get(app).studentDao()companion object {private const val PAGE_SIZE = 30/**如果启用了占位符，PagedList将报告完整的大小,但是有的Item在onBind方法中可能会为空(PagedListAdapter在加载数据时触发重新绑定） 如果禁用了占位符，onBind将永远不会收到null。如果你禁用占位符那么你应该禁用滚动条，不然随着页面已加载的增多，滚动条将随着新页面的加载而抖动 */ private const val ENABLE_PLACEHOLDERS = true } #Config可以设置页面显示的数量，是否启动占位符等等 val students = LivePagedListBuilder(dao.allStudentByName(), PagedList.Config.Builder() .setPageSize(PAGE_SIZE) .setEnablePlaceholders(ENABLE_PLACEHOLDERS) .build()).build() //直接插入到数据库 fun insert(text: CharSequence) = ioThread { dao.insert(Student(id = 0, name = text.toString())) } //从数据库删除 fun remove(cheese: Student) = ioThread { dao.delete(cheese) } }

class MainActivity : AppCompatActivity() { private val viewModel by lazy(LazyThreadSafetyMode.NONE) { ViewModelProviders.of(this@MainActivity).get(StudentiewModel::class.java) }override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main)val adapter = StudentAdapter() cheeseList.adapter = adapter// 将adapter添加订阅到ViewModel，当列表改变时，Adapter中的item会被刷新viewModel.students.observe(this, Observer(adapter::submitList))initAddButtonListener() initSwipeToDelete() }private fun initSwipeToDelete() { ItemTouchHelper(object : ItemTouchHelper.Callback() { // //使Item能向左或向右滑动 override fun getMovementFlags(recyclerView: RecyclerView, viewHolder: RecyclerView.ViewHolder): Int = makeMovementFlags(0, ItemTouchHelper.LEFT or ItemTouchHelper.RIGHT)override fun onMove(recyclerView: RecyclerView, viewHolder: RecyclerView.ViewHolder, target: RecyclerView.ViewHolder): Boolean = false//当项被滑动时，通过ViewModel删除该项。列表项将会自动删除，因为adapter正在观察这个Live List。 override fun onSwiped(viewHolder: RecyclerView.ViewHolder?, direction: Int) { (viewHolder as? StudentViewHolder)?.student?.let { viewModel.remove(it) } } }).attachToRecyclerView(cheeseList) }private fun addStudnet() { val newCheese = inputText.text.trim() if (newCheese.isNotEmpty()) { viewModel.insert(newCheese) inputText.setText("") } }private fun initAddButtonListener() { addButton.setOnClickListener { addStudnet() }// 当用户点击屏幕键盘上的“完成”按钮时，保存item. inputText.setOnEditorActionListener({ _, actionId, _ -> if (actionId == EditorInfo.IME_ACTION_DONE) { addStudnet() return@setOnEditorActionListener true } false // action that isn't DONE occurred - ignore }) // 当用户单击按钮或按enter时，保存该 item. inputText.setOnKeyListener({ _, keyCode, event -> if (event.action == KeyEvent.ACTION_DOWN && keyCode == KeyEvent.KEYCODE_ENTER) { addStudnet() return@setOnKeyListener true } false // event that isn't DOWN or ENTER occurred - ignore }) } }

WorkManager

• 后台工作程序只能在特定条件下调度任务(例如只有设备处于充电状态，该任务才会运行)
• 一旦你调度了任务，就可以忘记任务的存在，调度程序应该提供在所需条件匹配的情况下保证任务运行。
• 每个任务可以与另外一个任务并行链接，以并行或顺序运行多个任务。

• 你必须拥有对任务的控制权，调度程序应该提供API以轻松取消计划任务。

• 你的应用程序可能会需要显示任务的状态。
• 假设你要上传照片并且需要在界面上显示上传的百分比。
• 调度程序必须提供API以轻松获取任务的当前状态，如果任务完成之后可以传递一些结果数据，那就更棒了！

• 调度程序API应该在所有的Android版本中都一样。

• Worker：指定您需要执行的任务。WorkManager API包含一个抽象Worker类。你扩展这个类并且在这里执行这个工作。
  
• WorkRequest：代表一个单独的任务。至少，WorkRequest对象指定应该执行任务的Worker类。但是，您也可以向WorkRequest对象添加细节，指定任务应该运行的环境。每个工作请求都有一个自动生成的唯一ID; 您可以使用ID来执行诸如取消排队任务或获取任务的状态等操作。WorkRequest是一个抽象类; 在您的代码中，您将使用一个直接子类，一个timeworkrequest（一次性）或PeriodicWorkRequest（周期性）。
  
  • WorkRequest.Builder：创建工作请求对象的构造类。同样，您将使用一个子类，OneTimeWorkRequest。建筑商或PeriodicWorkRequest.Builder。
  • Constraints：指定任务运行时间的限制（例如，“仅在连接到网络时”）。

• WorkManager：排队和管理工作请求。你传递你的WorkRequest 对象WorkManager来排队的任务。WorkManager调度任务的方式是分散系统资源的负载，同时遵守您指定的约束条件。
  
• WorkStatus：包含有关特定任务的信息。包含关于特定任务的信息。WorkManager为每个WorkRequest对象提供一个LiveData。LiveData保存一个WorkStatus对象; 通过观察这个LiveData，您可以确定任务的当前状态，并在任务完成后获得任何返回值。
  

implementation "android.arch.work:work-runtime-ktx:1.0.0-alpha01"

class AdWorker : Worker() { override fun doWork(): WorkerResult { //输入data val is_open = this.inputData.getBoolean("is_open_ad", false) if (is_open) { //模拟延时操作 Thread.sleep(10000) val ad = getAd() outputData = https://www.it610.com/article/Data.Builder().putString("key_ad", ad).build()Log.e("ad", "SUCCESS") return WorkerResult.SUCCESS } else { Log.e("ad", "FAILURE:") return WorkerResult.FAILURE }}private fun getAd(): String { return "我是广告君，没进刚哥知识星球的赶紧加入了啊~~" + System.currentTimeMillis() }}

val myConstraints = Constraints.Builder() .setRequiresDeviceIdle(true) .setRequiresCharging(true) .build()

class AdEngine { fun schedulAd() { val adReauest = OneTimeWorkRequestBuilder() .setInputData( Data.Builder().putBoolean("is_open_ad", true) .build() ) .setConstraints(myConstraints) .addTag("tag_ad") .build() WorkManager.getInstance().enqueue(adReauest) //保存任务ID val adRequestId = adReauest.id var arid by Preference("adRequestId", "") arid = adRequestId.toString()} //这是约束条件 @RequiresApi(Build.VERSION_CODES.M) val myConstraints = Constraints.Builder() .setRequiresDeviceIdle(true) .setRequiresCharging(true) .build() }

class Preference(val name: String, private val default: T) { private val prefs: SharedPreferences by lazy { App.instance.applicationContext.getSharedPreferences(name, Context.MODE_PRIVATE) }operator fun getValue(thisRef: Any?, property: KProperty<*>): T { Log.i("info", "调用$this 的getValue()") return getSharePreferences(name, default) }operator fun setValue(thisRef: Any?, property: KProperty<*>, value: T) { Log.i("info", "调用$this 的setValue() value参数值为：$value") putSharePreferences(name, value) }@SuppressLint("CommitPrefEdits") private fun putSharePreferences(name: String, value: T) = with(prefs.edit()) { when (value) { is Long -> putLong(name, value) is String -> putString(name, value) is Int -> putInt(name, value) is Boolean -> putBoolean(name, value) is Float -> putFloat(name, value) else -> throw IllegalArgumentException("This type of data cannot be saved!") }.apply() }@Suppress("UNCHECKED_CAST") private fun getSharePreferences(name: String, default: T): T = with(prefs) { val res: Any = when (default) { is Long -> getLong(name, default) is String -> getString(name, default) is Int -> getInt(name, default) is Boolean -> getBoolean(name, default) is Float -> getFloat(name, default) else -> throw IllegalArgumentException("This type of data cannot be saved!") } return res as T } }

class App :Application(){ companion object {// 伴生对象java里的静态属性 lateinit var instance: App private set }override fun onCreate() { super.onCreate() instance = this } }

，添加到LifecycleOwner（AppCompatActivity本身就是一个LifecycleOwner），我们就可以根据state的改变，改变TextView的内容。显示我们的广告语。结果我们会发现并不会直接调起来APP，这是为什么呢？
因为我们用的是LiveData，当Activity销毁后，LiveData处于未激活的状态，不回去接受数据的改变，只有Activity从新获得生命周期后，LiveData才会接受数据的变化，从而受到LiveData的通知，所以想要做坏事的同学，这条路行不通的，谷歌只是为了保证一些任务的可靠性，而不是保证你的App的生命。
当然任务可以执行就可以取消
WorkManager.getInstance().cancelByWorkId(uuid);
链式调用

WorkManager.getInstance（）. beginWith（workA1，workA2，workA3） .then （workB） .then（workC1，workC2）.enqueue（）;

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这样就完了吗？还有更复杂的链式调用 WorkContinuation大家可以自行学习下。

class Main2Activity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main2) button.setOnClickListener(View.OnClickListener { val adEngine: AdEngine = AdEngine() adEngine.schedulAd()showAd(this, textad) })showAd(this, textad) }}fun showAd(lifeowner: LifecycleOwner, textad: TextView) {var arid by Preference("adRequestId", "") if (!arid.equals("")) { val uuid = UUID.fromString(arid) //public abstract LiveData getStatusById(@NonNull UUID id); WorkManager.getInstance().getStatusById(uuid) .observe(lifeowner, android.arch.lifecycle.Observer { state ->if (state != null && state.state.isFinished) { val adResult = state.outputData.getString("key_ad", "无") textad.text = adResult} })}}

Slices

Slices 在国内应用的范围不广，重要是因为Slices是 Google Assistant 的延伸，谷歌希望使用者能过快速到达App里面的某个特点功能，举一例子就是，你对Google Assistant说你要回家，那么以前可能只会出现滴滴，Uber的选项，但是引进Slices之后会显示更加详细的数据列表，比如滴滴item下会出现到家多少距离，多少钱，是否立即打车等等。Google Assistant 在国内不好用，但是谷歌有这个功能开源我们自己其实也可以去实现，可能小米会把这个功能给小艾同学吧。
开始搭建我们的Slices吧。
注意注意：开发环境必须是Android Studio 3.2 以及以上，最低版本Android 4.4 (API level 19) ，我们可以从官网下载Android Studio 3.2 ，图标是黄色的，可以和我们之前的Android Studio 共存，相互没有干扰，讲实话Android Studio 3.2 真的处处是坑，特别和Kotlin配合，那真的是一言难尽，苦不堪言。
no.1
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如果没有这个选项的话

值得一说的是 依赖的版本真的很坑，注意是否依赖了正确的版本

implementation "androidx.slice:slice-core:1.0.0-alpha1" implementation "androidx.slice:slice-builders:1.0.0-alpha1"

no.2

class MySliceProvider : SliceProvider() { /** * Instantiate any required objects. Return true if the provider was successfully created, * false otherwise. */ override fun onCreateSliceProvider(): Boolean { return true }override fun onMapIntentToUri(intent: Intent?): Uri { // Note: implementing this is only required if you plan on catching URL requests. // This is an example solution. var uriBuilder: Uri.Builder = Uri.Builder().scheme(ContentResolver.SCHEME_CONTENT) if (intent == null) return uriBuilder.build() val data = https://www.it610.com/article/intent.data if (data != null && data.path != null) { val path = data.path.replace("/", "") uriBuilder = uriBuilder.path(path) } val context = context if (context != null) { uriBuilder = uriBuilder.authority(context.getPackageName()) } return uriBuilder.build() }override fun onBindSlice(sliceUri: Uri): Slice? { val context = getContext() ?: return null return if (sliceUri.path == "/") { // Path recognized. Customize the Slice using the androidx.slice.builders API. // Note: ANR and StrictMode are enforced here so don't do any heavy operations. // Only bind data that is currently available in memory. ListBuilder(context, sliceUri) .addRow { it.setTitle("URI found.") } .build() } else { // Error: Path not found. ListBuilder(context, sliceUri) .addRow { it.setTitle("URI not found.") } .build() } }override fun onSlicePinned(sliceUri: Uri?) { }override fun onSliceUnpinned(sliceUri: Uri?) { // Remove any observers if necessary to avoid memory leaks. } }

绑定Slice

override fun onBindSlice(sliceUri: Uri): Slice? { val activityAction = createActivityAction() return if (sliceUri.path == "/ssy") { ListBuilder(context, sliceUri, ListBuilder.INFINITY) .addRow { it.setTitle("URI found. 我是标题") it.setSubtitle("我是子标题") //设置Action it.setPrimaryAction(activityAction)} } .build() } else { ListBuilder(context, sliceUri, ListBuilder.INFINITY) .addRow { it.setTitle("URI not found.") } .build() } } //创建Action fun createActivityAction(): SliceAction { val intent = Intent(context, MainActivity::class.java) return SliceAction(PendingIntent.getActivity(context, 0, intent, 0), IconCompat.createWithResource(context, R.drawable.ic_launcher_background), "Open MainActivity." ) }

将URL转变成content URI

override fun onMapIntentToUri(intent: Intent?): Uri {var uriBuilder: Uri.Builder = Uri.Builder().scheme(ContentResolver.SCHEME_CONTENT) if (intent == null) return uriBuilder.build() val data = https://www.it610.com/article/intent.data if (data != null && data.path != null) { val path = data.path.replace("/ssy", "") uriBuilder = uriBuilder.path(path) } val context = context if (context != null) { uriBuilder = uriBuilder.authority(context.getPackageName()) } return uriBuilder.build() }

这样我们我们就完成了一个简单的Slice，什么？怎么用？下载这个slice-viewer.apk充当Google Assistant吧，然后我们需要做的是
adb shell am start -a android.intent.action.VIEW -d slice-content://com.simple.slicesapplication/ssy
蓝色的是我们自己的Content Uri，这样就会在slice-viewer.apk打开我们的slice了。


文章图片
image.png
点击会跳转到我们的app。
什么？觉得不够丰富？来来来，阿秀同志请坐下，有好东西给你
创建一个带有Togglebutton和进度条 的Slice和action，只需要替换我们上面的Slice和action即可

fun createBrightnessSlice(sliceUri: Uri): Slice { val toggleAction = SliceAction(createToggleIntent(), "Toggle adaptive brightness", true) return ListBuilder(context, sliceUri, ListBuilder.INFINITY) .addRow { it.apply { setTitle("Adaptive brightness") setSubtitle("Optimizes brightness for available light") //这是togglebutton setPrimaryAction(toggleAction) } }.addInputRange { it.apply { //这个是进度条 setInputAction(brightnessPendingIntent) setMax(100) setValue(45) } }.build() }fun createToggleIntent(): PendingIntent { val intent = Intent(context, MyBroadcastReceiver::class.java) return PendingIntent.getBroadcast(context, 0, intent, 0) }class MyBroadcastReceiver : BroadcastReceiver() {override fun onReceive(context: Context, intent: Intent) { if (intent.hasExtra(Slice.EXTRA_TOGGLE_STATE)) { Toast.makeText(context, "Toggled:" + intent.getBooleanExtra( Slice.EXTRA_TOGGLE_STATE, false), Toast.LENGTH_LONG).show() } }companion object { const val EXTRA_MESSAGE = "message" }

啥？就这些？你想点击Slice后，在Slice上面动态修改一些信息，这是你的应用吗？咋想这么多呢？好吧，怕你了，来来来（谷歌官网的代码有坑，真的有坑）

fun createDynamicSlice(sliceUri: Uri): Slice { return when (sliceUri.path) { "/ssy" -> { val toastAndIncrementAction = SliceAction(createToastAndIncrementIntent("Item clicked"), IconCompat.createWithResource(context, R.drawable.no1), "Increment.") ListBuilder(context, sliceUri, ListBuilder.INFINITY) .addRow { it.apply { setPrimaryAction(toastAndIncrementAction) setTitle("Count: ${MyBroadcastReceiver.receivedCount}") setSubtitle("Click me") } } .build() } else -> { ListBuilder(context, sliceUri, ListBuilder.INFINITY) .addRow { it.setTitle("URI not found.") } .build() } } }fun createToastAndIncrementIntent(s: String): PendingIntent { return PendingIntent.getBroadcast(context, 0, Intent(context, MyBroadcastReceiver::class.java) .putExtra(android.app.slice.Slice.EXTRA_TOGGLE_STATE, s), 0) }class MyBroadcastReceiver : BroadcastReceiver() {override fun onReceive(context: Context, intent: Intent) { if (intent.hasExtra(Slice.EXTRA_TOGGLE_STATE)) { Toast.makeText(context, "Toggled:" + intent.getBooleanExtra( Slice.EXTRA_TOGGLE_STATE, false), Toast.LENGTH_LONG).show() receivedCount++; context.contentResolver.notifyChange(sliceUri, null) } }companion object { var receivedCount = 0 val sliceUri = Uri.parse("content://com.simple.slicesapplication/ssy") const val EXTRA_MESSAGE = "message" } }

这回行了吧，什么布局能不能改？啥你想加广告？真是，好吧好吧
Slice templates 这个大哥叫切片模板
定义你的切片模板 切片是通过使用ListBuilder构造的 。ListBuilder允许您添加列表中显示的不同类型的行。本节介绍每种行类型及其构造方式。
SliceAction
Slice模板的最基本元素是 SliceAction。SliceAction包含一个标签以及一个PendingIntent， 并且是以下之一：

• 图标按钮
• 默认切换
• 自定义切换（具有开/关状态的可绘图）

切片模板 SliceAction由本节其余部分描述的模板构建器使用。SliceAction可以定义一个图像模式，用于确定如何为该动作呈现图像：

• ICON_IMAGE：尺寸小，可上色
• SMALL_IMAGE：体积小，不可着色
• LARGE_IMAGE：最大的尺寸和不可着色

HeaderBuilder
在大多数情况下，您应该使用HeaderBuilder为您的模板设置标题 。标头可以支持以下内容：

• 标题
• 字幕
• 摘要字幕
• 主要行动

下面显示了一些示例头部配置。请注意，灰色框显示潜在的图标和填充位置：


文章图片
image.png 标题在不同的表面上呈现 当需要切片时，显示表面决定如何渲染切片。请注意，托管表面之间的渲染可能有所不同。
在较小的格式中，通常只显示标题（如果存在）。如果您为标题指定了摘要，则会显示摘要文本而不是字幕文本。
如果您没有在模板中指定标题，则通常会显示添加到ListBuilder的第一行


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image.png
那我们就试一下

fun createSliceWithHeader(sliceUri: Uri): Slice= ListBuilder(context, sliceUri, ListBuilder.INFINITY) .setAccentColor(0xff0F9D) // Specify color for tinting icons .setHeader { it.apply { setTitle("Get a ride") setSubtitle("Ride in 4 min") setSummary("Work in 1 hour 45 min | Home in 12 min") } }.addRow { it.apply { setTitle("Home") setSubtitle("12 miles | 12 min | $9.00") addEndItem(IconCompat.createWithResource(context, R.drawable.ic_launcher_background), SliceHints.ICON_IMAGE) } } .build() }

文章图片
image.png
感觉有点意思了，不过还是没有想象中该有的样子。上下标题差不多有了，右边的icon可以多几个吗？

fun createSliceWithActionInHeader(sliceUri: Uri): Slice { // Construct our slice actions. val noteAction = SliceAction(takeNoteIntent, IconCompat.createWithResource(context, R.drawable.a), ICON_IMAGE, "Take note")val voiceNoteAction = SliceAction(voiceNoteIntent, IconCompat.createWithResource(context, R.drawable.b), ICON_IMAGE, "Take voice note")val cameraNoteAction = SliceAction(cameraNoteIntent, IconCompat.createWithResource(context, R.drawable.c), ICON_IMAGE, "Create photo note")// Construct the list. return ListBuilder(context, sliceUri, ListBuilder.INFINITY) .setAccentColor(0xfff4b4) // Specify color for tinting icons .setHeader { it.apply { setTitle("Create new note") setSubtitle("Easily done with this note taking app") } } .addAction(noteAction) .addAction(voiceNoteAction) .addAction(cameraNoteAction) .build() }

文章图片
image.png
最后来个全家桶


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image.png

fun createSliceWithGridRow(sliceUri: Uri): Slice { // Create the parent builder. val icon_a = IconCompat.createWithResource(context, R.mipmap.a) val icon_b = IconCompat.createWithResource(context, R.mipmap.b) val icon_c = IconCompat.createWithResource(context, R.mipmap.c) val icon_d = IconCompat.createWithResource(context, R.mipmap.d) val intent = Intent(context, MainActivity::class.java) val brightnessPendingIntent = PendingIntent.getActivity(context, 0, intent, 0) return ListBuilder(context, sliceUri, ListBuilder.INFINITY) .setHeader { it.apply { setTitle("玩具") setPrimaryAction(SliceAction(brightnessPendingIntent, icon_c, "Famous restaurants")) } } .addRow { it.apply {setSubtitle("12 miles | 12 min | $9.00") addEndItem(IconCompat.createWithResource(context, R.mipmap.b), SliceHints.LARGE_IMAGE) } }.addGridRow { it.apply { addCell { it.apply { addImage(icon_a, LARGE_IMAGE) addTitleText("积木") addText("￥100") setContentIntent(brightnessPendingIntent) } } addCell { it.apply { addImage(icon_b, LARGE_IMAGE) addTitleText("摇杆") addText("￥200") setContentIntent(brightnessPendingIntent) } } addCell { it.apply { addImage(icon_c, LARGE_IMAGE) addTitleText("十合一卡") addText("￥300") setContentIntent(brightnessPendingIntent) } } addCell { it.apply { addImage(icon_d, LARGE_IMAGE) addTitleText("手柄t") addText("￥200") setContentIntent(brightnessPendingIntent) } } } } .build() }

本篇把Paging、WorkManager、Slices的概念和简单的应用梳理了一遍，其中也发现了很多坑，网上好多文章，只是讲原理不写实例，或者有的人写了实例但是自己没有验证过，就是谷歌文档也有很多不清楚的地方，特别是Kotlin的依赖的配置，所幸把大部分的问题解决 了，不过还有一些问题依然不清楚，查看了官方文档，谷歌了众多文章可是资料很少，希望有小伙伴可以给解惑。一起学习。
【JetPack|JetPack （Paging、WorkManager、Slices介绍和使用方式）】大家可以点个关注，告诉我大家想要深入探究哪些问题，希望看到哪方面的文章，我可以免费给你写专题文章。。哈哈。。。
希望大家多多支持。。你的一个关注，是我坚持的最大动力。。

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