Stripe – The Payment Solution

• Client side:
  Stripe provide Stripe.js library which you can add to your project by using script tag like,

<script src="https://js.stripe.com/v3/"></script>

Step 2 : Get Secret API Key And Publishable Key

Before accessing any Stripe API you need a secret API key which you can get from the stripe dashboard.

1. Open stripe dashboard
2. Expand developers menu from left hand menu
3. Select API keys option.
4. On the right side, under the standard keys click on the reveal key token button and copy the API key.

We need a Publishable key for web clients. You can get that by following the same steps given above but instead of a secret key you need to copy the publishable key.

Stripe.apiKey = "sk_test_4***************";

Map<String, Object> customerParams = new HashMap<>();
customerParams.put("email", "john@example.com");
customerParams.put("name", "John S");

// creating customer on stripe
Customer customer = Customer.create(customerParams);

After creating a customer you are able to add a card. Adding a card is needed to be done from the client side but before that you need a client secret that is present in the setup intent object, so first we need to create Setup Intent which should be created at server side.

Step 4: Create Setup Intent

• Server side:

Setup Intent object contains client secret that you need to pass to Stripe.js while creating a card from the web.

Stripe.apiKey = "sk_test_4***************";
Map<String, Object> params = new HashMap<>();
params.put("customer", id);
SetupIntent intent = SetupIntent.create(params);

You can get client secrets from the above setup intent by calling getClientSecret() method.

Step 5: Add Card

Add card is should be done from client side because we can’t expose user card details by using our server API. If you want to check the added card on the server side, Stripe provides web hooks that we can catch at our server and get the card details which are added.

• Create stripe object by providing publishable key as follows,

var stripe = ('pk_test_***********');

• Create element to accept card details, first create object of element and than use it to create card element in DOM

var element = stripe.elements();
var cardElement = element.create("card");

• Mount card element in DOM

<label for="card-element">Card</label>
<div id="card-element"></div>

<script>
  cardElement.mount('#card-element');
</script>

• Confirm the setup intent

var cardholderName = document.getElementById('cardholder-name');
var cardButton = document.getElementById('card-button');
var clientSecret = cardButton.dataset.secret;

cardButton.addEventListener('click', function(ev) {
stripe.confirmCardSetup(
clientSecret,
{
payment_method: {
card: cardElement,
billing_details: {
name: cardholderName.value,
},
},
}
).then(function(result) {
if (result.error) {
// Display error.message in your UI.
} else {
// The setup has succeeded. Display a success message.
}
});
});

After successful execution you will get payment method id in the result.setupIntent.payment_method field. This id is useful in the further process of payment.

Step 6: Pay Using Saved Cards.

Now, when we want to pay some amount with a selected payment method i.e. card, we can pass payment method id and customer id from client to server with our internal API and calculate amount at server side based on conditions or you can pass that through the same api where you are passing payment method id.

• Server-side:
  • First, you need to create PaymentIntent

Long amount = (long) ((100-50) * 100); //Your amount calculation
PaymentIntentCreateParams createParams = PaymentIntentCreateParams.builder()
.setAmount(amount).setCurrency("usd")
.setPaymentMethod("paymentMethodId")
.setCustomer(customerId)
.setDescription("About payment")
.setConfirmationMethod(PaymentIntentCreateParams 
.ConfirmationMethod.MANUAL).build();

PaymentIntent intent = PaymentIntent.create(createParams);

In the above code snippet, first we created parameters for payment intent where you need currency, amount and customer id as mandatory fields.

**Note:-Main thing we need to keep in mind here is the Confirmation Method that should be manual for future payments. If you put it as an auto then payment will get captured immediately.

After successful execution you can save this payment intent id in the database.

Step 7: Capture Actual Payment

When you are ready to capture the payment you just need Payment Intent id to that.

PaymentIntent paymentIntent = PaymentIntent.retrieve("paymentIntentId");
paymentIntent = paymentIntent.confirm();

If you need a receipt of payment you can retrieve from charges object which is present in above payment intent as follows,

Charge charge = paymentIntent.getCharges().getData().iterator().next();
String url = charge.getReceiptUrl();

Step 8: Testing

Stripe provides some test cards suitable to different test cases. Here are the some samples from them,