使用Kotlin 1.3在Android中迁移到Kotlin协程 [英] Migrate to Kotlin coroutines in Android with Kotlin 1.3

问题描述

我应该在我的build.gradle文件中进行哪些更改或导入类以在带有Kotlin 1.3的Android项目中使用稳定的协程函数?

What should I change in my build.gradle file or import in classes to use stable coroutine functions in my Android project with Kotlin 1.3 ?

我的build.gradle

implementation "org.jetbrains.kotlin:kotlin-coroutines-core:$coroutines_version" implementation "org.jetbrains.kotlin:kotlin-coroutines-android:$coroutines_version"

implementation "org.jetbrains.kotlin:kotlin-coroutines-core:$coroutines_version" implementation "org.jetbrains.kotlin:kotlin-coroutines-android:$coroutines_version"

我当然使用Android Studio 3.3预览

Of course I use Android Studio 3.3 Preview

推荐答案

在build.gradle中，将库更改为

implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.1.1'.

删除(如果已添加):

kotlin {
    experimental {
        coroutines "enable"
    }
}

在代码中将launch更改为GlobalScope.launch(Dispatchers.IO)或GlobalScope.launch(Dispatchers.Main).

更新

请使用局部协程上下文而不是全局范围(例如，参见 http://kotlinlang.org/docs/reference/coroutines/coroutine-context-and-dispatchers.html ).

Please, use local coroutine context instead of global scope (see, for instance, http://kotlinlang.org/docs/reference/coroutines/coroutine-context-and-dispatchers.html).

活动

请参见 https://github.com /Kotlin/kotlinx.coroutines/blob/master/ui/coroutines-guide-ui.md .

实施CoroutineScope:

class YourActivity : AppCompatActivity(), CoroutineScope {

添加局部变量job并将其初始化:

Add a local variable job and initialize it:

private lateinit var job: Job

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)

    job = Job()
}

创建一个协程上下文并在Activity销毁时将其取消:

Create a coroutine context and cancel it on Activity destroy:

override fun onDestroy() {
    job.cancel()
    super.onDestroy()
}

override val coroutineContext: CoroutineContext
    get() = Dispatchers.Main + job

对于片段(与Activity中的相同)

实施协程范围:

class YourFragment : Fragment(), CoroutineScope {

创建一个局部变量job，并在onCreate()中对其进行初始化. (我尝试编写private val job: Job = Job()，但遇到了一个问题，即在ViewPager中您将创建Fragment s及其作业.由于我们将在ViewPager中刷卡时取消onDestroy()中的job重新创建工作).

Create a local variable job and initialize it in onCreate(). (I tried to write private val job: Job = Job(), but bumped into problem that in ViewPager you will create Fragments and their jobs. As we will cancel the job in onDestroy() during swiping in ViewPager, we should recreate the job).

private lateinit var job: Job

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)

    ...
    job = Job()
}

创建一个协程上下文并在Fragment destroy上将其取消:

Create a coroutine context and cancel it on Fragment destroy:

override val coroutineContext: CoroutineContext
    get() = Dispatchers.Main + job // You can use different variants here. 

override fun onDestroy() {
    job.cancel()
    super.onDestroy()
}

启动示例

照常使用launch:

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
    super.onViewCreated(view, savedInstanceState)
    launch {
        // Wait for result of I/O operation without blocking the main thread.
        withContext(Dispatchers.IO) {
            interactor.getCountry().let {
                countryName = it.name
            }
        }

        // Update views in the UI thread.
        country.updateCaption(countryName)
    }
}

就我而言，当我将API请求与常规回调一起使用时，出现了问题.尚未调用回调内部的launch内部.所以我用交互器重写了该代码.

In my case a problem occured when I used API requests with usual callbacks. A launch interior inside a callback hasn't been called. So I rewrote that code with interactors.

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