Stripe Payments & SaaS Billing Systems · 课时

处理异步事件的 Webhook

设置并处理 Webhook，以响应来自 Stripe 的异步事件；这对于支付完成后更新应用状态至关重要。

处理异步事件的 Webhook 是 CoddyKit 上的免费 Stripe Payments & SaaS Billing Systems 课时。这是第 2 节课，共 4 节。你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。这是 Stripe Payments & SaaS Billing Systems 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Stripe Payments & SaaS Billing Systems 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

Payments Aren't Always Instant

When you process payments, things don't always happen instantly. Think about a bank transfer: it takes time for funds to move and clear. This is called an asynchronous event.

Your application needs a way to know when these background processes are complete or if something important changes with a payment.

Webhooks: Your Payment Alarms

This is where webhooks come in! A webhook is an automated message sent from one application to another when a specific event occurs.

They act like 'alarms' or 'notifications'.
Instead of your app constantly asking Stripe, 'Is the payment done yet?' (known as 'polling'), Stripe tells your app directly when something happens.

Stripe's Event Notifications

Stripe uses webhooks to notify your application about important events in your account. These could be:

A payment succeeding or failing.
A refund being issued.
A customer's subscription changing.

By listening to these events, your app can update its own records, send customer emails, or trigger other business logic.

Key Webhook Event Types

There are many types of webhook events, but some are crucial for payment processing:

payment_intent.succeeded: A payment has been successfully captured.
charge.refunded: A refund has been processed for a charge.
customer.subscription.updated: A customer's subscription plan or status has changed.

You choose which events your application wants to receive notifications for.

Setting Up Your Webhook Endpoint

To receive webhook events, you need to provide Stripe with a special URL on your server. This URL is called your webhook endpoint.

When an event occurs, Stripe sends an HTTP POST request to this URL, containing the event data. You configure this URL and select event types in your Stripe Dashboard.

Your Server Listens In

Your webhook endpoint is just a regular HTTP endpoint in your application. It waits for Stripe to send data. Here's a conceptual look at what such an endpoint might do:

public class WebhookController {
  @PostMapping("/stripe-webhook")
  public ResponseEntity<String> handleWebhook(@RequestBody String payload, @RequestHeader("Stripe-Signature") String sigHeader) {
    // 1. Verify the signature (CRUCIAL!)
    // 2. Parse the event payload
    // 3. Process the event based on its type
    return new ResponseEntity<>("Event received", HttpStatus.OK);
  }
}

Trust, But Verify!

Imagine someone malicious sends fake payment success messages to your webhook endpoint. Without verification, your app might mistakenly grant access to a service or ship a product without payment!

This is why webhook signature verification is absolutely critical. It ensures that incoming events truly originate from Stripe and haven't been tampered with.

Secure Your Webhook Endpoint

Stripe sends a unique signature in the Stripe-Signature header with each webhook event. You use your unique webhook secret (from your Stripe Dashboard) to compute a matching signature locally.

If the signatures match, you can trust the event. Here's how you'd use the Stripe Java library to do this:

import com.stripe.model.Event;
import com.stripe.exception.SignatureVerificationException;
import com.stripe.net.Webhook;

public class VerifyWebhook {
  public static void main(String[] args) {
    // In a real app, these come from the HTTP request:
    String jsonPayload = "{"id":"evt_test","object":"event","type":"payment_intent.succeeded"}";
    String stripeSignatureHeader = "t=1678886400,v1=5d53a9f0a... (truncated)"; // Placeholder
    String webhookSecret = "whsec_your_secret_here"; // Get this from Stripe Dashboard

    System.out.println("--- Webhook Signature Verification ---");

    try {
      Event event = Webhook.constructEvent(
          jsonPayload, stripeSignatureHeader, webhookSecret
      );

      System.out.println("✅ Webhook signature verified!");
      System.out.println("Event Type: " + event.getType());
      // Now process the 'event' object safely
    } catch (SignatureVerificationException e) {
      System.err.println("❌ Verification FAILED: " + e.getMessage());
      System.err.println("Make sure the signature and secret are correct.");
    } catch (Exception e) {
      System.err.println("An unexpected error occurred: " + e.getMessage());
    }
  }
}

Robust Event Handling

Beyond security, your webhook handler should be robust:

Respond Quickly (200 OK): Stripe expects a 200 status code within a few seconds. If not, it might retry the event.
Idempotency: Design your handler to process the same event multiple times without causing duplicate actions. Stripe might resend events.
Asynchronous Processing: Don't do heavy processing directly in the webhook endpoint. Delegate tasks to background jobs (e.g., queues) to respond quickly.

Webhook Security Question

Why is it crucial to verify the signature of incoming webhook events from Stripe?

Recap: Webhooks for Async Events

You've learned how webhooks are essential for handling asynchronous events in payment processing:

They provide real-time notifications from Stripe.
You configure an endpoint and listen for specific event types.
Signature verification is critical for security.
Robust handlers respond quickly and process events idempotently.

Mastering webhooks is key to building reliable and secure payment integrations!

常见问题解答

「处理异步事件的 Webhook」课时是免费的吗？

是的 — 「处理异步事件的 Webhook」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Stripe Payments & SaaS Billing Systems 课程的其余内容，请升级到 CoddyKit PRO。 Stripe Payments & SaaS Billing Systems 课程共包含 4 节课。

「处理异步事件的 Webhook」这节课中我会学到什么？

设置并处理 Webhook，以响应来自 Stripe 的异步事件；这对于支付完成后更新应用状态至关重要。你通过在浏览器中直接运行的动手代码来练习 Stripe Payments & SaaS Billing Systems，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 Stripe Payments & SaaS Billing Systems 需要有经验吗？

无需任何先前经验。CoddyKit 上的 Stripe Payments & SaaS Billing Systems 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。这是第 2 节课，共 4 节。

「处理异步事件的 Webhook」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 Stripe Payments & SaaS Billing Systems 课中编写并运行代码吗？

能。每节 Stripe Payments & SaaS Billing Systems 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

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