如何从 Xamarin 项目中的跨平台页面打开和关闭 Android 活动

Question

I have cross-platform app, but one function in my app can work only in Android (GooglePay). I created an activity for it, and trying to open this activity in Xamarin Form page using DependencyService:

IPay pay = DependencyService.Get<IPay>();
Console.WriteLine(pay.GetResult());

Code of my activity is in this answer

So, as I understand, I need to call it with Bundle object, because I got an exception in this code:

PaymentsClient paymentsClient = WalletClass.GetPaymentsClient(
             this,
             new WalletClass.WalletOptions.Builder()
                     .SetEnvironment(WalletConstants.EnvironmentTest)
                     .Build()
        );

As I understand, activity is null without a bundle. Exception is:

Java.Lang.NullPointerException. Message = Attempt to invoke virtual method 'android.content.Context android.content.Context.getApplicationContext()' on a null object reference

So, I cannot find, if it is the right way to open an activity, and, if it is right, how to create right Bundle.

Answer 1

Google provides the SupportWalletFragment class, which will display a branded Purchase button within the fragment:

var walletFragment = SupportWalletFragment.NewInstance (WalletFragmentOptions.NewBuilder ()
    .SetEnvironment (WalletConstants.EnvironmentSandbox)
    .SetMode (WalletFragmentMode.BuyButton)
    .SetTheme (WalletConstants.ThemeLight)
    .SetFragmentStyle (new WalletFragmentStyle ()
        .SetBuyButtonText (BuyButtonText.BuyWithGoogle)
        .SetBuyButtonAppearance (BuyButtonAppearance.Classic)
        .SetBuyButtonWidth (Dimension.MatchParent))
    .Build ());

The MaskedWalletRequest class is used to build a new purchase request. You could use any payment gateway that can accept EMVCO Network Tokens, or in this case set up your Stripe account as the payment gateway with some configuration options:

var maskedWalletRequest = MaskedWalletRequest.NewBuilder ()

// Request credit card tokenization with Stripe
.SetPaymentMethodTokenizationParameters (
    PaymentMethodTokenizationParameters.NewBuilder ()
        .SetPaymentMethodTokenizationType (PaymentMethodTokenizationType.PaymentGateway)
        .AddParameter ("gateway", "stripe")
        .AddParameter ("stripe:publishableKey", STRIPE_PUBLISHABLE_KEY)
        .AddParameter ("stripe:version", "1.15.1")
        .Build ())
    .SetShippingAddressRequired (true)
    .SetMerchantName ("Xamarin")
    .SetPhoneNumberRequired (true)
    .SetShippingAddressRequired (true)
    .SetEstimatedTotalPrice ("20.00")
    .SetCurrencyCode ("USD")
    .Build();

For more details you could check the devblogs .

You could also use the plugin InAppBillingPlugin from Nuget. And get started by reading through the In-App Billing Plugin documentation .

Answer 2

Well, finally, I found the way to solve this problem.

Used this sourse - not funcional, works only with GPay India, but have some good points:

• Use MessagingCenter to send data to native code and get it back
• Use MainActivity, because it is only activity, that can work with 'null' Bundle

So now my code:

long orderId = 1;
long sum = 1;
long[] data = new long[2] {orderId, sum };

MessagingCenter.Send((App)Xamarin.Forms.Application.Current, "PayViaGooglePay", data);

MessagingCenter.Subscribe<App, string>((App)Application.Current, $"tokenteleportation{orderId}", async (sender, arg) =>
        {
// getting result from arg
}

And code in MainActivity:

MessagingCenter.Subscribe<App, long[]>((App)Xamarin.Forms.Application.Current, "PayViaGooglePay", (sender, arg) =>
        {
            OrderId = arg[0];
            PayViaGooglePay(this, arg[1]);
        });

//sending request, getting token

MessagingCenter.Send((App)Xamarin.Forms.Application.Current, $"tokenteleportation{OrderId}", TOKEN);