Kotlin coroutines resumeWithException错误。

Question

我决定用kotlin的程序来获取设备的位置（一次，不更新），所以最后我得到了这个代码。

@SuppressLint("MissingPermission")
suspend fun LocationManager.getCurrentLocationOnce(): Location {
    return suspendCancellableCoroutine { continuation ->
        try {
            val locationListener = object : SimpleLocationListener {
                override fun onLocationChanged(location: Location?) {
                    if (location == null) {
                        [email protected](this)
                        continuation.resumeWithException(FailedToRetrieveLocationException("Location is NULL"))
                    } else {
                        [email protected](this)
                        continuation.resume(location)
                    }
                }

                override fun onProviderEnabled(provider: String?) {}

                override fun onProviderDisabled(provider: String?) {
                    [email protected](this)
                    continuation.resumeWithException(ProviderDisabledException(provider ?: ""))
                }

            }

            this.requestSingleUpdate(
                LocationManager.GPS_PROVIDER,
                locationListener,
                null
            )
        } catch (e : Exception) {
            continuation.resumeWithException(e)
        }
    }
}

当GPS开启时，一切正常，但当GPS关闭时，程序失败，出现异常 ProviderDisabledException这就是原因。

override fun onProviderDisabled(provider: String?) {
                    [email protected](this)
                    continuation.resumeWithException(ProviderDisabledException(provider ?: ""))
                }

但我不知道为什么会失败，因为在我使用这个函数的地方，我已经有了。

try {
            val locationManager = (requireActivity().getSystemService(Context.LOCATION_SERVICE) as? LocationManager)
                ?: throw FailedToRetrieveLocationException("Location Service is null")
            val location = locationManager.getCurrentLocationOnce()
            log("[GOOGLE] downloadRestaurantsWithGPSLocationGoogle",
                "Successfully got location={lat:${location.latitude}, long:${location.longitude}}")
            downloadRestaurantsWithLocation(location)
        } catch (ex : FailedToRetrieveLocationException) {
            logError("[GOOGLE] downloadRestaurantsWithGPSLocationGoogle", ex)
            throw ex
        } catch (providerException : ProviderDisabledException) {
            logError("[GOOGLE] downloadRestaurantsWithGPSLocationGoogle", providerException)
            throw providerException
        } catch (e : Exception) {
            logError("[GOOGLE] downloadRestaurantsWithGPSLocationGoogle", e)
            throw e
        }

所以我记录了异常，然后把它重新扔给调用者函数 在调用者函数中，我捕捉到了这个异常。

            try {
                    log("[GOOGLE] downloadRestaurants", "Starting donwload restaurants for GOOGLE")
                    downloadRestaurantsWithGPSLocationGoogle()
                } catch (e : Exception) {
                    logError("[GOOGLE] error happened while getting location", e)
                    downloadRestaurantsWithFusedLocationGoogle()
                }

而在错误的堆栈跟踪中，我只得到了这个。

E/[GOOGLE] downloadRestaurantsWithGPSLocationGoogle: my.package.location.exceptions.ProviderDisabledException: Provider gps disabled
        at my.package.common.location.LocationUtilsKt$getCurrentLocationOnce$$inlined$suspendCancellableCoroutine$lambda$1.onProviderDisabled(LocationUtils.kt:45)
        at android.location.LocationManager$ListenerTransport._handleMessage(LocationManager.java:384)
        at android.location.LocationManager$ListenerTransport.access$000(LocationManager.java:300)
        at android.location.LocationManager$ListenerTransport$1.handleMessage(LocationManager.java:316)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:207)
        at android.app.ActivityThread.main(ActivityThread.java:6878)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:876)

我不知道为什么应用程序会失败，因为像这样的代码是完美的。

lifecycleScope.launch {
    try {
        throwError()
    } catch (e : Exception) {
        e.printStackTrace()
    }
}

private suspend fun throwError() {
    return suspendCancellableCoroutine { continuation ->
        continuation.resumeWithException(ProviderDisabledException("TEST"))
    }
}

Answer 1

所以，我终于意识到为什么它会让应用崩溃了=)。所有的coroutines都没问题。

问题出在这个方法上。

@Throws(ProviderDisabledException::class, FailedToRetrieveLocationException::class)
private fun downloadRestaurantsWithGPSLocationGoogle() = lifecycleScope.launch {
    log("[GOOGLE] downloadRestaurantsWithGPSLocationGoogle", "Trying to get location via GPS")
    try {
        val locationManager = (requireActivity().getSystemService(Context.LOCATION_SERVICE) as? LocationManager)
            ?: throw FailedToRetrieveLocationException("Location Service is null")
        val location = locationManager.getCurrentLocationOnce()
        log("[GOOGLE] downloadRestaurantsWithGPSLocationGoogle",
            "Successfully got location={lat:${location.latitude}, long:${location.longitude}}")
        downloadRestaurantsWithLocation(location)
    } catch (ex : FailedToRetrieveLocationException) {
        ex.printStackTrace()
        logError("[GOOGLE] downloadRestaurantsWithGPSLocationGoogle", ex)
        throw ex
    } catch (providerException : ProviderDisabledException) {
        providerException.printStackTrace()
        logError("[GOOGLE] downloadRestaurantsWithGPSLocationGoogle", providerException)
        throw providerException
    } catch (e : Exception) {
        e.printStackTrace()
        logError("[GOOGLE] downloadRestaurantsWithGPSLocationGoogle", e)
        throw e
    }
}

问题是我从coroutine中抛出了异常，而不是在coroutine中处理这个异常，所以我启动了我的coroutine，所有的try-cathces都被跳过了，因为这里我使用的是fire and forget风格。所以为了解决这个问题，我需要用这个方法暂停并抛出异常。试图捕捉错误的地方。

private fun downloadRestaurants() = lifecycleScope.launch {
        log("downloadRestaurantsWithLocationSort",
            "Requesting Manifest.permission.ACCESS_COARSE_LOCATION & Manifest.permission.ACCESS_FINE_LOCATION permissions")
        val user = requestPermissions(
            Manifest.permission.ACCESS_COARSE_LOCATION,
            Manifest.permission.ACCESS_FINE_LOCATION
        )
        if (!user.any { !it.second }) {
            // permission is granted, can download restaurants and sort by nearest
            log("downloadRestaurantsWithLocationSort", "Permissions is granted")
            log("MANUFACTURER", Build.MANUFACTURER)
            if (Build.MANUFACTURER == "Huawei" || Build.MANUFACTURER == "HUAWEI") {
                showToast("HUAWEI")
                try {
                    log("[HUAWEI] downloadRestaurants", "Starting donwload restaurants for HUAWEI")
                    downloadRestaurantsWithGPSLocationHuawei()
                } catch (e : Exception) { // this will not work, because FIRE and FORGET
                    e.printStackTrace()
                    logError("[HUAWEI] error happened while getting location", e)
                    mainViewModel.downloadRestaurantsHeaders(null)
                }
            } else {
                showToast("NOT A HUAWEI")
                try {
                    log("[GOOGLE] downloadRestaurants", "Starting donwload restaurants for GOOGLE")
                    downloadRestaurantsWithGPSLocationGoogle()
                } catch (e : Exception) { // this will not work, because FIRE and FORGET
                    e.printStackTrace()
                    logError("[GOOGLE] error happened while getting location", e)
                    downloadRestaurantsWithFusedLocationGoogle()
                }
            }
        } else {
            // permission is not granted, just download the restaurants
            log("downloadRestaurantsWithLocationSort", "Permissions is NOT granted")
            mainViewModel.downloadRestaurantsHeaders(null)
        }
    }

所以答案是： downloadRestaurantsWithGPSLocationGoogle 和 downloadRestaurantsWithFusedLocationGoogle 暂停，不要在它们里面单独启动coroutine。(删除 lifecycleScope.launch)