从 API 获取 GET 数据

Your board can pull data from the internet the same way a browser does: by making an HTTP request to a URL. 🌐

A GET request asks a server, please send me this data. It only reads, it never changes anything on the other side.

Before any request, your ESP must already be on WiFi. Without a network connection there is nowhere to send the request.

The HTTPClient library gives you simple functions to make requests. Include it at the top of your sketch.

Make an HTTPClient object, then point it at your target URL with begin(). This sets up the request you are about to send.

Call GET() to fire the request. It returns an HTTP status code that tells you whether the server liked your request.

A code of 200 means success. Always check it before trusting the data, since 404 or 500 means something went wrong.

When the status is good, grab the actual data with getString(). This is the text the server sent back to you.

Call end() when you are done. This closes the connection and frees memory so the next request starts clean.

A negative status code does not come from the server. It means the request failed on your side, often no WiFi or a bad URL.

Add a delay between requests so you do not flood the API. Most services limit how often you may ask for data.

Your code received an HTTP status of 200. What does that tell you?

You connected, called GET(), checked for 200, read the body with getString(), and closed with end(). That is a full read from the web. 🎉