How to implement OAuth flow for streaming platform API using Java HTTP calls

[Luke_Brilliant]

I’m working on a Java application that needs to connect to a popular streaming service’s chat system. I’ve already set up my application credentials and obtained the necessary client ID from their developer portal.

The issue I’m facing is implementing the OAuth authorization code flow using native Java HTTP requests. I want to avoid using external libraries if possible and stick to the built-in HTTP client functionality.

Here’s a basic example of what I’m trying to achieve:

public class StreamAuthenticator {
    private String clientSecret = "your_app_secret";
    private String applicationId = "your_app_id";
    private String callbackUrl = "http://localhost:8080/callback";
    
    public void initiateAuthFlow() {
        String authEndpoint = "https://api.streaming-service.com/oauth/authorize";
        String params = "client_id=" + applicationId + 
                       "&redirect_uri=" + callbackUrl + 
                       "&response_type=code";
        // How do I handle the redirect and token exchange?
    }
}

What’s the proper way to handle the authorization callback and exchange the code for an access token? Any guidance would be helpful since I’m still learning HTTP request handling in Java.

[danwilson85]

just wrapped this up last week and hit the same problems. the redirect handling is what’ll get you - your HttpServer context path has to match the callback URL exactly or you won’t catch the auth code. also, token expiration is a pain since most streaming APIs only give you 1-hour tokens, so build in refresh logic from the start. 1 thing that caught me off guard: some services need PKCE even when their docs barely mention it.

[Grace_31Dance]

OAuth flows get tricky when you’re handling browser stuff from Java. You’ll want to use Desktop.getDesktop().browse() to pop open the auth URL in their default browser. Set up your HttpServer to catch the callback, then shut it down right after you get the authorization code - otherwise you’ll tie up that port.

Here’s the gotcha: when you’re building your token request, the headers matter way more than you’d think. Most streaming services are super picky about User-Agent strings and will just reject anything that looks generic. I found this out the hard way - kept getting 403s even though my parameters were perfect.

One more thing - treat those tokens like passwords. They’re basically keys to user accounts, so encrypt them if you’re saving to disk.

[CreativePainter33]

Handling the callback with localhost redirects can indeed be complex. To manage this, I suggest using HttpServer from com.sun.net.httpserver to listen on the designated callback port. Upon successful authorization, a GET request will be sent with the authorization code in the query parameters. Capture that code and then perform a POST request to the token endpoint using HttpClient. Ensure to include parameters such as grant_type=authorization_code, along with the captured code, client_id, client_secret, and redirect_uri as form data in your request. Typically, streaming services return a JSON response containing your access_token and refresh_token. Additionally, consider implementing the state parameter for security: create a random string, append it to your authorization URL, and validate it upon receiving the callback.

[olivias]

You’re missing the local server setup to catch the callback and handle the token exchange. I just built something like this - you need a simple HTTP server running on your callback port to grab the authorization code. Once you pull the code from the callback URL params, POST it to the token endpoint with your client credentials. The streaming service sends back an access token as JSON. Don’t forget to set Content-Type to application/x-www-form-urlencoded for the token exchange. Here’s what tripped me up: some streaming APIs need specific scopes in your auth URL, so check their docs for required permissions. And URL-encode your parameters or you’ll get auth failures.