Toast.makeText 当我在 Android Studio 的异步线程中调用它时会导致应用程序崩溃吗？

Question

以下代码是关于Google基于应用内支付的办公示例code。

我必须在真实的移动设备中测试它 phone 因为很难在 Android Studio 模拟器中测试 Google 应用内支付。

不幸的是，当我打开 FragmentBuy 时，该应用程序在真实移动设备 phone 中崩溃了，我几乎没有得到有关崩溃的错误信息。

我再次检查了我的代码，我猜有两个地方导致崩溃，一个是 private fun processPurchases(purchasesResult: Set<Purchase>) ，另一个是 private fun acknowledgeNonConsumablePurchasesAsync(nonConsumables: List<Purchase>).

1：他们在异步线程中启动Toast.makeTex，是崩溃的原因吗？

2：Billing.getInstance(requireActivity(), getString(R.string.skuRegisterApp))和Billing.getInstance(requireContext), getString(R.string.skuRegisterApp))哪个正确？

3：我的代码还有其他问题吗？

FragmentBuy.kt

class FragmentBuy : Fragment() {

    private lateinit var binding: LayoutBuyBinding

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
        binding = DataBindingUtil.inflate(
            inflater, R.layout.layout_buy, container, false
        )
   
        val mBilling=Billing.getInstance(requireActivity(), getString(R.string.skuRegisterApp)) // or Billing.getInstance(requireContext), getString(R.string.skuRegisterApp))

        mBilling.initBillingClient()

        binding.btnPurchase.setOnClickListener {
           mBilling.purchaseProduct(requireActivity())
        }

        return binding.root
    }

}

fun Context.toast(msg: String){
    Toast.makeText(this, msg, Toast.LENGTH_LONG).show()
}


fun Fragment.toast(@StringRes resId: Int) {
    toast(requireContext().getString(resId))
}

Billing.kt

class Billing private constructor (private val mContext: Context, private val purchaseItem :String)
        :PurchasesUpdatedListener, BillingClientStateListener   {

     private lateinit var playStoreBillingClient: BillingClient
     private val mapSkuDetails = mutableMapOf<String,SkuDetails>()

     fun initBillingClient() {
         playStoreBillingClient = BillingClient
             .newBuilder(mContext)
             .enablePendingPurchases() // required or app will crash
             .setListener(this)
             .build()

         if (!playStoreBillingClient.isReady) {
             playStoreBillingClient.startConnection(this)
         }
     }

    override fun onBillingSetupFinished(billingResult: BillingResult) {
        when (billingResult.responseCode) {
            BillingClient.BillingResponseCode.OK -> {
                querySkuDetailsAsync(BillingClient.SkuType.INAPP, listOf(purchaseItem) )
                queryAndProcessPurchasesAsync()
                mContext.toast(R.string.msgBillINIOK)
            }
            ...
        }
    }

    private fun querySkuDetailsAsync(@BillingClient.SkuType skuType: String, skuList: List<String>) {
        val params = SkuDetailsParams.newBuilder().setSkusList(skuList).setType(skuType).build()
        playStoreBillingClient.querySkuDetailsAsync(params) { billingResult, skuDetailsList ->
            when (billingResult.responseCode) {
                BillingClient.BillingResponseCode.OK -> {
                    if (skuDetailsList.orEmpty().isNotEmpty()) {
                        skuDetailsList?.forEach {
                            mapSkuDetails.put(it.sku,it)
                        }
                    }
                }
                '''
            }
        }
    }

    private fun queryAndProcessPurchasesAsync() {
        val purchasesResult = HashSet<Purchase>()
        var result = playStoreBillingClient.queryPurchases(BillingClient.SkuType.INAPP)
        result?.purchasesList?.apply { purchasesResult.addAll(this) }

        processPurchases(purchasesResult)
    }


    private fun processPurchases(purchasesResult: Set<Purchase>): Job {
        return CoroutineScope(Job() + Dispatchers.IO).launch {
            val validPurchases = HashSet<Purchase>(purchasesResult.size)
            purchasesResult.forEach { purchase ->
                if (purchase.purchaseState == Purchase.PurchaseState.PURCHASED) {
                    if (purchase.sku.equals(purchaseItem)) {
                        if (isSignatureValid(purchase)) {
                            validPurchases.add(purchase)
                            setIsRegisteredAppAsTrue(mContext)
                            mContext.toast(R.string.msgOrderOK)  //Will it be crash?
                        }
                    }
                }
                ...

            }
            acknowledgeNonConsumablePurchasesAsync(validPurchases.toList())
        }
    }


    private fun acknowledgeNonConsumablePurchasesAsync(nonConsumables: List<Purchase>) {
        nonConsumables.forEach { purchase ->
            val params = AcknowledgePurchaseParams.newBuilder()
                           .setPurchaseToken(purchase
                           .purchaseToken).build()

            playStoreBillingClient.acknowledgePurchase(params) { billingResult ->
                when (billingResult.responseCode) {
                    BillingClient.BillingResponseCode.OK -> {
                         mContext.toast(R.string.msgOrderAcknowledgeOK)     //Will it be crash?
                    }
                    else -> mContext.toast(R.string.msgOrderAcknowledgeError, billingResult.debugMessage)
                }
            }
        }
    }



    //执行playStoreBillingClient.launchBillingFlow(...)后 launch
    override fun onPurchasesUpdated(billingResult: BillingResult, purchases: MutableList<Purchase>?) {
        when (billingResult.responseCode) {
            BillingClient.BillingResponseCode.OK -> {
                purchases?.apply { processPurchases(this.toSet()) }
            }
            ...
        }
    }


    fun purchaseProduct(activity: Activity) {
        val skuDetails = mapSkuDetails[purchaseItem]
        skuDetails?.let{
            val purchaseParams = BillingFlowParams.newBuilder().setSkuDetails(skuDetails).build()
            playStoreBillingClient.launchBillingFlow(activity, purchaseParams)
        }
    }


    companion object {
        private const val LOG_TAG = "BillingRepository"

        private var INSTANCE: Billing? = null
        fun getInstance(mContext: Context, purchaseItem: String): Billing =
                     INSTANCE ?: synchronized(this) {
                         INSTANCE ?: Billing(mContext, purchaseItem).also { INSTANCE = it }
                     }
    }


}

Answer 1

要显示 Toast 你的 Thread 必须有 MessageQueue，在这种情况下，我建议你使用 Activity 而不是 Context 并使用方法 runOnUiThread

mActivity.runOnUiThread { 
    // show your Toast
}

Answer 2

对于任何界面更改，请调用 activity.runOnUiThread(runnable)。

并使用 Kotlin 调用

activity.runOnUiThread{
   toast("Your text") //since you are using extension function.
}

Answer 3

因为Toast在源代码中被Handler使用了。

private static class TN extends ITransientNotification.Stub {
    TN(String packageName, @Nullable Looper looper) {
        //There need the Looper first
        if (looper == null) {
            // Use Looper.myLooper() if looper is not specified.
            looper = Looper.myLooper();
            if (looper == null) {
                throw new RuntimeException(
                        "Can't toast on a thread that has not called Looper.prepare()");
            }
        }
        mHandler = new Handler(looper, null) {
            @Override
            public void handleMessage(Message msg) {
                switch (msg.what) {
                    case SHOW: {
                        IBinder token = (IBinder) msg.obj;
                        handleShow(token);
                        break;
                    }
                }
            }
        };
    }

    /**
     * schedule handleShow into the right thread
     */
    @Override
    @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 115609023)
    public void show(IBinder windowToken) {
        if (localLOGV) Log.v(TAG, "SHOW: " + this);
        //the show is used Handler
        mHandler.obtainMessage(SHOW, windowToken).sendToTarget();
    }
}

这是Toast源码中的TN，之所以显示Toast是Handler使用的，所以需要在Main Thread.If中使用需要在异步线程中使用Toast，我们需要创建一个Looper.

 new Thread(){
        @Override
        public void run() {
            super.run();
            Looper.prepare();
            Toast.makeText(MainActivity.this,"",Toast.LENGTH_SHORT).show();
            Looper.loop();
        }
    }.start();

Answer 4

是的。您只能显示来自 UI 主线程的 toast 消息。要从任何其他线程启动 toask 消息，您可以像这样使用 Hander：

 new Handler(Looper.getMainLooper()).post(() -> {
        Toast.makeText(someContext, "some toast", Toast.LENGTH_SHORT).show();
 });

此外，您必须使用 activity 上下文，而不是片段上下文。要从片段中获取 activity 上下文，您可以使用：

getActivity()

所以你可以在你的片段中做这样的事情：

 new Handler(Looper.getMainLooper()).post(() -> {
            Toast.makeText(getActivity(), "some toast", Toast.LENGTH_SHORT).show();
 });

由于您使用的是扩展函数，因此需要将其更改为使用 activity 上下文：

fun Fragment.toast(@StringRes resId: Int) {
    getActivity().toast(requireContext().getString(resId))
}

然后您可以在处理程序中使用 toast()（以从不同的线程显示它）：

 new Handler(Looper.getMainLooper()).post(() -> {
        toast("some toast")
 });

第一个更正确，但您应该在 activity 的上下文中使用 getString()：

Billing.getInstance(requireActivity(), getActivity().getString(R.string.skuRegisterApp))
其他一切似乎都很好

Toast.makeText 当我在 Android Studio 的异步线程中调用它时会导致应用程序崩溃吗？

Will Toast.makeText cause app crash when I invoke it in asynchronous thread in Android Studio?

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