How can I stream real-time OpenAI API responses in Java using OkHttp?

Below is an example using OkHttp to call the completion endpoint in streaming mode. Note that OpenAI’s streaming endpoint returns data as Server-Sent Events (SSE), so you may receive lines that start with "data:" and even a termination message (often "[DONE]"). This example reads the response line by line and prints out the streamed content.

JAVACopied
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;
import okhttp3.MediaType;
import okio.BufferedSource;
import java.io.IOException;

public class OpenAiStreamExample {
    private static final String API_URL = "https://api.openai.com/v1/completions";
    private static final String API_KEY = "your-api-key"; // Replace with your API key

    public static void main(String[] args) {
        OkHttpClient client = new OkHttpClient();
        MediaType mediaType = MediaType.parse("application/json; charset=utf-8");

        String json = "{" +
                "\"model\": \"text-davinci-003\", " +
                "\"prompt\": \"Say this is a test\", " +
                "\"stream\": true" +
                "}";

        RequestBody requestBody = RequestBody.create(json, mediaType);
        Request request = new Request.Builder()
                .url(API_URL)
                .post(requestBody)
                .addHeader("Authorization", "Bearer " + API_KEY)
                .build();

        try (Response response = client.newCall(request).execute()) {
            if (!response.isSuccessful()) {
                throw new IOException("Unexpected response code " + response);
            }

            BufferedSource source = response.body().source();
            while (!source.exhausted()) {
                String line = source.readUtf8Line();
                if (line != null && !line.trim().isEmpty()) {
                    // Lines usually start with "data:"
                    if (line.startsWith("data: ")) {
                        String data = line.substring("data: ".length()).trim();
                        // Check for stream termination marker
                        if ("[DONE]".equals(data)) {
                            break;
                        }
                        System.out.println(data);
                    }
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Explanation

• OkHttpClient and Request:
  We create a new OkHttp client and build a POST request to the OpenAI completions endpoint. The request includes our JSON payload with the "stream": true flag.

• RequestBody:
  The JSON payload is sent with the appropriate content type.

• Streaming Response Handling:
  We obtain a BufferedSource from the response body and then loop through the data line by line. SSE responses typically include lines starting with "data: ", which we trim and process. In this example, if the stream returns a line with [DONE], it breaks from the loop.

This sample should help you receive partial results in real time from the OpenAI API when using streaming mode.