Kotlin 协程 viewModelScope 中的改造调用 [英] Retrofit call in Kotlin Coroutines viewModelScope

问题描述

最近我更新了我的 ViewModel 以使用新的 viewModelScope.从它的实现中，我看到 Dispatchers.Main.immediate 被设置为 viewModelScope 的默认 CoroutineDispatcher.

Recently I've updated my ViewModel to use new viewModelScope. From its' implementation, I see that Dispatchers.Main.immediate is set as the default CoroutineDispatcher for viewModelScope.

因此，当在 viewModelScope.launch 中打印当前的 Thread 时，它会给出 Thread[main,5,main]

So when printing the current Thread in viewModelScope.launch it gives Thread[main,5,main]

但这是我的问题.虽然它在主线程中运行，但以下代码对我来说适用，它执行网络调用.

But here is my question. Although this runs in Main Thread, the following code works for me which performs a network call.

viewModelScope.launch {
    userRepo.login(email, password)
}

这里的userRepo.login(email, password)是suspend函数，调用Retrofitsuspend函数.

Here userRepo.login(email, password) is suspend function, which calls Retrofit suspend function.

那么这是如何工作的，如果我的当前线程是主线程?

So how this works, if my Current Thread is Main Thread?

推荐答案

之所以有效，是因为 Retrofit 的 suspend 实现委托给 Call.enqueue.这意味着它默认已经在自己的后台执行器上执行，而不是使用调用者的 Dispatcher.

It works because Retrofit's suspend implementation delegates to Call<T>.enqueue. This means it already executes on its own background executor by default instead of using the caller's Dispatcher.

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