在Kotlin中制作功能块

问题描述

我很感谢您可能已经回答了这个问题，但是我找不到适合我的解决方案.

I appreciate that this may have already been answered but I'm unable to find a solution that works for me.

Tl; dr:如何制作功能块?

Tl;dr: How do make a function block?

我有以下Kotlin中为Android API 28编写的与BLE相关的代码.

I have the following BLE-related code written in Kotlin for Android API 28.

override fun onServicesDiscovered(gatt: BluetoothGatt?, status: Int) {

    for (gattService: BluetoothGattService in gatt!!.services) {

        for (gattChar: BluetoothGattCharacteristic in gattService.characteristics) {

                if (gattChar.uuid.toString().contains(ADC_SAMPLESET_0) && !subscribed_0) {

                    subscribed_0 = true

                    gatt.setCharacteristicNotification(gattChar, true)

                    val descriptor = gattChar.getDescriptor(
                            UUID.fromString(BleNamesResolver.CLIENT_CHARACTERISTIC_CONFIG)
                    )
                    descriptor.value = BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE
                    gatt.writeDescriptor(descriptor)
                }

上面的if语句被重复多次以促进订阅多个BLE特性.不幸的是，gatt.writeDescriptor()函数异步运行.在调用gatt.writeDescriptor()获取下一个特性之前，我需要等待它返回.我该如何实现?

The if-statement above is repeated multiple times to facilitate subscription to multiple BLE characteristics. Unfortunately, the gatt.writeDescriptor() function runs asynchronously. I need to wait for it to return before calling gatt.writeDescriptor() for the next characteristic. How do I achieve this?

我已经尝试在kotlinx.coroutines.experimental.*中使用runBlocking和GlobalScope.launch，但是我不能完全确定它们是否正确.

I've tried using runBlocking and GlobalScope.launch in kotlinx.coroutines.experimental.* but I'm not entirely sure that they're the right thing.

谢谢，亚当

推荐答案

onDescriptorWrite()方法可能会有所帮助.您应该已经覆盖了它.

The onDescriptorWrite() method might be helpful. You should already be overriding it.

请尝试以下操作:

private var canContinue = false;

override fun onServicesDiscovered(gatt: BluetoothGatt, status: Int) { //gatt shouldn't be null, so the null-safe ? isn't needed
    loopAsync(gatt);
}

override fun onDescriptorWrite(gatt: BluetoothGatt, descriptor: BluetoothGattDescriptor, status: Int) {
    canContinue = true; //allow the loop to continue once a descriptor is written
}

private fun loopAsync(gatt: BluetoothGatt) {
    async { //Run it async
        gatt.services.forEach { gattService -> //Kotlin has a handy Collections.forEach() extension function
            gattService.characteristics.forEach { gattChar -> //Same for this one
                if (gattChar.uuid.toString().contains(ADC_SAMPLESET_0) && !subscribed_0) {
                    subscribed_0 = true

                    gatt.setCharacteristicNotification(gattChar, true)

                    val descriptor = gattChar.getDescriptor(
                            UUID.fromString(BleNamesResolver.CLIENT_CHARACTERISTIC_CONFIG)
                    }
                    descriptor.value = BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE
                    gatt.writeDescriptor(descriptor)
                    while(!canContinue); //wait until canContinue becomes true and then continue
                }
            }
        }
    }
}

这有点hacky.可能有一种使用递归的方法，但是嵌套的for循环使这一过程变得棘手.

This is a little hacky. There is probably a way to do this with recursion, but the nested for loops make that tricky.

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