为何在服务器端内购验证中复用Google Access Token而非每次申领新令牌？

Great question—this is a common point of confusion when working with Google's OAuth 2.0 tokens for server-side in-app purchase validation. Let’s break down the key reasons why reusing valid access tokens is the better approach:

• Avoid hitting API rate limits
  Google enforces strict rate limits on all its API endpoints, including the token refresh endpoint. If you request a new access token for every single purchase validation, you’ll quickly burn through your quota, leading to 429 Too Many Requests errors. This would grind your validation workflow to a halt, which is critical to avoid in production systems handling user purchases.

• Reduce latency and improve performance
  Each request for a new access token adds an extra round-trip to Google’s servers. For every purchase validation, you’d first have to fetch the token, then send the actual validation request. This extra network call increases the total time taken to process the purchase, hurting both user experience (if users are waiting for purchase confirmation) and your server’s overall throughput.

• Minimize authentication overhead
  The refresh token flow is explicitly designed to cut down on repeated heavy authentication. Instead of re-sending your client credentials (client ID, client secret) and going through full authorization checks every time, you just use the long-lived refresh token to get a new access token quickly. This reduces the chance of errors from repeated credential submissions and streamlines the entire process.

• Increase system stability
  More external requests mean more points of failure. If Google’s token endpoint experiences temporary downtime or high latency, a "request new token every time" approach would break your entire validation pipeline. Reusing a valid access token lets you continue processing purchases normally until the token expires, giving you a buffer against external service disruptions.

That said, if your system handles an extremely low volume of validation requests, you might not run into these issues—but for any production-grade service, reusing valid access tokens is the standard, recommended practice.

内容的提问来源于stack exchange，提问作者GuyC