Android kotlin协程

说明

可代替线程整异步
可控制，灵活（控制优先级，内存占用等）
速度快效率高
有数量上限

使用

runBlocking 一般用于测试不建议使用
GlobalScope.launch 全局的生命周期跟随application 不建议使用
CoroutineScope(job) 用
基本使用

  runBlocking {Log.i("test_coroutine","我是一个runBlocking")}Log.i("test_coroutine","我在 runBlocking 协程外 且在 协程后")GlobalScope.launch {Log.i("test_coroutine","我是一个GlobalScope")}Log.i("test_coroutine","我在 GlobalScope 协程外 且在 协程后")val job = Job()val coroutineScope = CoroutineScope(job)coroutineScope.launch {Log.i("test_coroutine","我是一个coroutineScope")}Log.i("test_coroutine","我在 coroutineScope 协程外 且在 协程后")

结果
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分析

runBlocking 阻塞主线程执行了协程后继续执行

GlobalScope.launch 不阻塞继续执行主线程后执行协程
coroutineScope.launch 不阻塞继续执行主线程后执行协程

增加延时，效果更明显 delay(1000)

  runBlocking {delay(1000)Log.i("test_coroutine","我是一个runBlocking")}Log.i("test_coroutine","我在 runBlocking 协程外 且在 协程后")GlobalScope.launch {delay(1000)Log.i("test_coroutine","我是一个GlobalScope")}Log.i("test_coroutine","我在 GlobalScope 协程外 且在 协程后")val job = Job()val coroutineScope = CoroutineScope(job)coroutineScope.launch {delay(1000)Log.i("test_coroutine","我是一个coroutineScope")}Log.i("test_coroutine","我在 coroutineScope 协程外 且在 协程后")

结果
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分析

runBlocking 阻塞主线程执行了协程后继续执行

GlobalScope.launch 协程内容最后执行
coroutineScope.launch 协程内容最后执行

1.1 协程里的挂起

 val coroutineScope = CoroutineScope(Job())val job = coroutineScope.launch {delay(1000)Log.i("test_coroutine","我是一个coroutineScope")      //1launch {delay(1000)Log.i("test_coroutine","我是一个coroutineScope 里的 launch")  // 4delay(1000)Log.i("test_coroutine","我是一个coroutineScope 里的 launch1")  //5}Log.i("test_coroutine","我是一个coroutineScope1")  // 2Log.i("test_coroutine","我是一个coroutineScope2")  // 3}

结果
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继续玩

 val coroutineScope = CoroutineScope(Job())val job = coroutineScope.launch {delay(1000)Log.i("test_coroutine","我是一个coroutineScope")   //1launch {delay(1000)Log.i("test_coroutine","我是一个coroutineScope 里的 launch")  //3delay(1000)Log.i("test_coroutine","我是一个coroutineScope 里的 launch1")  //5}Log.i("test_coroutine","我是一个coroutineScope1")  //2delay(1500)                                          //多了个delayLog.i("test_coroutine","我是一个coroutineScope2")  //4}

结果
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join()

 val coroutineScope = CoroutineScope(Job())val job = coroutineScope.launch {delay(1000)Log.i("test_coroutine","我是一个coroutineScope")  //1val job1 = launch {delay(1000)Log.i("test_coroutine","我是一个coroutineScope 里的 launch")  //3delay(1000)Log.i("test_coroutine","我是一个coroutineScope 里的 launch1")  //4}Log.i("test_coroutine","我是一个coroutineScope1")  //2job1.join()delay(1500)                                          //多了个delayLog.i("test_coroutine","我是一个coroutineScope2")  //5}

结果：执行的时候 job1加入了进来
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cancel()

 val coroutineScope = CoroutineScope(Job())val job = coroutineScope.launch {delay(1000)Log.i("test_coroutine","我是一个coroutineScope")  //1val job1 = launch {delay(1000)Log.i("test_coroutine","我是一个coroutineScope 里的 launch")  //3delay(1000)Log.i("test_coroutine","我是一个coroutineScope 里的 launch1")  //不执行}Log.i("test_coroutine","我是一个coroutineScope1")  //2delay(1500)                                          //多了个delayLog.i("test_coroutine","我是一个coroutineScope2")  //4cancel()}

结果 job 和子job1都停了
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job1.cancel()

 val coroutineScope = CoroutineScope(Job())val job = coroutineScope.launch {delay(1000)Log.i("test_coroutine","我是一个coroutineScope")val job1 = launch {delay(1000)Log.i("test_coroutine","我是一个coroutineScope 里的 launch")delay(1000)Log.i("test_coroutine","我是一个coroutineScope 里的 launch1")}Log.i("test_coroutine","我是一个coroutineScope1")delay(1500)                                          //多了个delayLog.i("test_coroutine","我是一个coroutineScope2")job1.cancel()Log.i("test_coroutine","我是一个coroutineScope3")}

结果 job继续执行 job1停了
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job1.cancelAndJoin() 执行完之后取消

  val coroutineScope = CoroutineScope(Job())val job = coroutineScope.launch {delay(1000)Log.i("test_coroutine","我是一个coroutineScope")val job1 = launch {var i = 0while(i<10){yield()delay(500)Log.i("test_coroutine","我是一个coroutineScope 里的 launch>>${i++}")}}Log.i("test_coroutine","我是一个coroutineScope1")delay(1500)                                          //多了个delayLog.i("test_coroutine","我是一个coroutineScope2")job1.join()job1.cancel()Log.i("test_coroutine","我是一个coroutineScope3")}

结果 job1并没有被取消
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job1.cancelAndJoin()

   val coroutineScope = CoroutineScope(Job())val job = coroutineScope.launch {delay(1000)Log.i("test_coroutine","我是一个coroutineScope")val job1 = launch {var i = 0while(i<10){yield()delay(500)Log.i("test_coroutine","我是一个coroutineScope 里的 launch>>${i++}")}}Log.i("test_coroutine","我是一个coroutineScope1")delay(1500)                                          //多了个delayLog.i("test_coroutine","我是一个coroutineScope2")job1.cancelAndJoin()Log.i("test_coroutine","我是一个coroutineScope3")}

结果
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ensureActive() 在协程不在 active 状态时会立即抛出异常。
yield() yield 会进行的第一个工作就是检查任务是否完成，如果 Job 已经完成的话，就会抛出 CancellationException 来结束协程。yield 应该在定时检查中最先被调用
async

 val async = async {var i = 0while(i<10 && isActive){delay(500)Log.i("test_coroutine","我是一个coroutineScope 里的 launch>>${i++}")}"完事啦"}Log.i("test_coroutine","我是一个coroutineScope1")delay(1500)                                          //多了个delayLog.i("test_coroutine","我是一个coroutineScope2")val result = async.await()Log.i("test_coroutine","我是一个coroutineScope3 result>"+result)Log.i("test_coroutine","我是一个coroutineScope4")

结果
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withTimeout

 Log.i("test_coroutine","我是一个coroutineScope")withTimeout(3000){var i = 0while(i<10 && isActive){delay(500)Log.i("test_coroutine","我是一个coroutineScope 里的 launch>>${i++}")}}Log.i("test_coroutine","我是一个coroutineScope1")delay(1500)                                          //多了个delayLog.i("test_coroutine","我是一个coroutineScope2")

结果时间到后所在的协程也不继续执行了
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Android中的协程

MainScope

MainScope().launch {}

viewModelScope
implementation ‘androidx.lifecycle:lifecycle-viewmodel-android:2.8.0’
implementation ‘androidx.lifecycle:lifecycle-viewmodel-ktx:2.8.0’
implementation ‘androidx.lifecycle:lifecycle-common:2.8.0’

 viewModelScope.launch {}

lifecycleScope

  lifecycleScope.launch {}

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rememberCoroutineScope() 可能会因为组件状态变化而移除此协程

@Composable
inline fun rememberCoroutineScope(crossinline getContext: @DisallowComposableCalls () -> CoroutineContext ={ EmptyCoroutineContext }
): CoroutineScope {val composer = currentComposerval wrapper = remember {CompositionScopedCoroutineScopeCanceller(createCompositionCoroutineScope(getContext(), composer))}return wrapper.coroutineScope
}

currentRecomposeScope currentRecomposeScope 是一个在任何Composable函数中都能访问的成员
作用是使当前时刻组合无效，强制触发重组

val currentRecomposeScope: RecomposeScope@ReadOnlyComposable@OptIn(InternalComposeApi::class)@Composable get() {val scope = currentComposer.recomposeScope ?: error("no recompose scope found")currentComposer.recordUsed(scope)return scope}