public class Main {

    // Add your Computer Vision key and endpoint to your environment variables.
    // After setting, close and then re-open your command shell or project for the changes to take effect.
    private static String key = "PASTE_YOUR_COMPUTER_VISION_KEY_HERE";
    private static String endpoint = "PASTE_YOUR_COMPUTER_VISION_ENDPOINT_HERE";

    private static String uriBase = endpoint + "/vision/v3.1/read/analyze";

    private static String imageToAnalyze =
            "https://raw.githubusercontent.com/MicrosoftDocs/azure-docs/master/articles/cognitive-services/Computer-vision/Images/readsample.jpg";

    public static void main(String[] args) {
        CloseableHttpClient httpTextClient = HttpClientBuilder.create().build();
        CloseableHttpClient httpResultClient = HttpClientBuilder.create().build();;

        System.out.println("Endpoint:         " + endpoint);
        System.out.println("key: " + key);

        try {
            // This operation requires two REST API calls. One to submit the image
            // for processing, the other to retrieve the text found in the image.

            URIBuilder builder = new URIBuilder(uriBase);

            // Prepare the URI for the REST API method.
            URI uri = builder.build();
            HttpPost request = new HttpPost(uri);

            // Request headers.
            request.setHeader("Content-Type", "application/json");
            request.setHeader("Ocp-Apim-Subscription-Key", key);

            // Request body.
            StringEntity requestEntity =
                    new StringEntity("{\"url\":\"" + imageToAnalyze + "\"}");
            request.setEntity(requestEntity);

            // Two REST API methods are required to extract text.
            // One method to submit the image for processing, the other method
            // to retrieve the text found in the image.

            // Call the first REST API method to detect the text.
            HttpResponse response = httpTextClient.execute(request);

            // Check for success.
            if (response.getStatusLine().getStatusCode() != 202) {
                // Format and display the JSON error message.
                HttpEntity entity = response.getEntity();
                String jsonString = EntityUtils.toString(entity);
                JSONObject json = new JSONObject(jsonString);
                System.out.println("Error:\n");
                System.out.println(json.toString(2));
                return;
            }

            // Store the URI of the second REST API method.
            // This URI is where you can get the results of the first REST API method.
            String operationLocation = null;

            // The 'Operation-Location' response header value contains the URI for
            // the second REST API method.
            Header[] responseHeaders = response.getAllHeaders();
            for (Header header : responseHeaders) {
                if (header.getName().equals("Operation-Location")) {
                    operationLocation = header.getValue();
                    break;
                }
            }

            if (operationLocation == null) {
                System.out.println("\nError retrieving Operation-Location.\nExiting.");
                System.exit(1);
            }

            // If the first REST API method completes successfully, the second
            // REST API method retrieves the text written in the image.
            //
            // Note: The response may not be immediately available. Text
            // recognition is an asynchronous operation that can take a variable
            // amount of time depending on the length of the text.
            // You may need to wait or retry this operation.

            System.out.println("\nText submitted.\n" +
                    "Waiting 10 seconds to retrieve the recognized text.\n");
            Thread.sleep(10000);

            // Call the second REST API method and get the response.
            HttpGet resultRequest = new HttpGet(operationLocation);
            resultRequest.setHeader("Ocp-Apim-Subscription-Key", key);

            HttpResponse resultResponse = httpResultClient.execute(resultRequest);
            HttpEntity responseEntity = resultResponse.getEntity();

            if (responseEntity != null) {
                // Format and display the JSON response.
                String jsonString = EntityUtils.toString(responseEntity);
                JSONObject json = new JSONObject(jsonString);
                System.out.println("Text recognition result response: \n");
                System.out.println(json.toString(2));
            }
        } catch (Exception e) {
            System.out.println(e.getMessage());
        }
    }
}