Android按钮单击事件的Kotlin协程流程示例? [英] Kotlin coroutine flow example for Android button click event?

问题描述

我曾经使用Channel将点击事件从Anko View类发送到Activity类，但是越来越多的Channel函数被标记为已弃用.所以我想开始使用Flow api.

I used to use Channel to send out click event from Anko View class to Activity class, however more and more Channel functions are marked as deprecated. So I wanted to start using Flow apis.

我在下面迁移了代码:

private val btnProduceChannel = Channel<Unit>()
val btnChannel : ReceiveChannel<Unit> = btnProduceChannel 

// Anko
button {
    onClick {
        btnProduceChannel.send(Unit)
    }
}

收件人:

lateinit var btnFlow: Flow<Unit>
    private set

button {
    btnFlow = flow { 
       onClick { 
            emit(Unit) 
       }
    }
}

我现在必须将流属性标记为var，它不像以前那样优雅.这样对吗?定义属性时可以像Flow一样初始化Rx Subject吗?

I have to mark flow properties as var now which is not so elegant as before. Is this way right? Can I init a Rx Subject like Flow when defining the property?

我拿回Channel，然后用consumeAsFlow():

private val btnChannel = Channel<Unit>()

// This can be collected only once
val btnFlow = btnChannel.consumeAsFlow()

// Or add get() to make property can be collected multiple times
// But the "get()" can be easily forgotten and I don't know the performance of create flow every access
val btnFlow get() = btnChannel.consumeAsFlow()


// Send event with btnChannel

这似乎比lateinit var好，但是有什么方法可以完全摆脱Channel? (尽管Flow本身像callbackFlow，channelFlow一样使用频道)

This seems better than lateinit var one, but any way to get rid of Channel completely? (Though Flow itself like callbackFlow, channelFlow are using channel)

推荐答案

尽管我没有在项目中使用Anko，但是我已经编写了此函数与常规按钮引用一起使用，请查看它是否对您有帮助:

Although I don't use Anko in my project, I've written this function to use with regular button references, see if it helps you:

fun View.clicks(): Flow<Unit> = callbackFlow {
    setOnClickListener {
        offer(Unit)
    }
    awaitClose { setOnClickListener(null) }
}

可能的用法示例是:

button.clicks()
   .onEach { /*React on a click event*/ }
   .launchIn(lifecycleScope)

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