Refreshing OAuth token with okhttp interceptors. All requests will wait until token refresh finished, and then will continue with the new token.

Interceptor.java

private class HttpInterceptor implements Interceptor {

	@Override
	public Response intercept(Chain chain) throws IOException {
		Request request = chain.request();

		//Build new request
		Request.Builder builder = request.newBuilder();
		builder.header("Accept", "application/json"); //if necessary, say to consume JSON
		
		String token = settings.getAccessToken(); //save token of this request for future
		setAuthHeader(builder, token); //write current token to request

		request = builder.build(); //overwrite old request
		Response response = chain.proceed(request); //perform request, here original request will be executed

		if (response.code() == 401) { //if unauthorized
			synchronized (httpClient) { //perform all 401 in sync blocks, to avoid multiply token updates
				String currentToken = settings.getAccessToken(); //get currently stored token

				if(currentToken != null && currentToken.equals(token)) { //compare current token with token that was stored before, if it was not updated - do update

					int code = refreshToken() / 100; //refresh token
					if(code != 2) { //if refresh token failed for some reason
						if(code == 4) //only if response is 400, 500 might mean that token was not updated
							logout(); //go to login screen
						return response; //if token refresh failed - show error to user
					}
				}

				if(settings.getAccessToken() != null) { //retry requires new auth token,
					setAuthHeader(builder, settings.getAccessToken()); //set auth token to updated
					request = builder.build();
					return chain.proceed(request); //repeat request with new token
				}
			}
		}

		return response;
	}
	
	private void setAuthHeader(Request.Builder builder, String token) {
		if (token != null) //Add Auth token to each request if authorized
			builder.header("Authorization", String.format("Bearer %s", token));
	}
	
	private int refreshToken() {
		//Refresh token, synchronously, save it, and return result code
		//you might use retrofit here
	}
	
	private int logout() {
		//logout your user
	}
}

@jaswanthm how to implement refresh token with Authenticator but avoid multiply token updates from different threads?

Hi.How do you implement the logout function within the interceptor? is The intercpetor standalone class or a part of an activity?

@Kolyall
In example synchronized block is used to avoid multiple tokens updates.

@andrconstruction
What kind of logout you need to implement?
Usually it's enough to "forget" api key (and then to not send it to server)

@paragones Did you find a way to refresh the token using rxjava?

@paragones Did you find a way to refresh the token using rxjava?

https://gist.github.com/mpetlyuk/77ac3221c1776d14654374faf2985d5a
look at my implementation. Include my transformer into each request observable via mehtod Observable.compose(/* refresh transformer*/)

Very useful. Thanks!

This is very good. Thanks for sharing this.
Only issue with this implementation is after token gets refreshed, all other requests get executed in serial.
Is there a way to make execution of those requests parallel?

private int refreshToken() {
		//Refresh token, synchronously, save it, and return result code
		//you might use retrofit here
}

So you are proposing to use retrofit inside Interceptor to refresh token? This is quite ugly workaround.