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Using Retrofit in Java

Retrofit is a type-safe HTTP client library for Java and Android. It simplifies the process of consuming RESTful web services by generating Java interface definitions based on RESTful API endpoints. Retrofit handles the boilerplate code for making HTTP requests and parsing responses, making it easy to work with web APIs in Java applications.

We've implemented a code sample that you can re-use to convert your HTML documents to PDF, JPG, PNG or WEBP using PDFShift and Java:

import okhttp3.MediaType;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;

import org.json.JSONObject;

import java.nio.file.Files;
import java.nio.file.Paths;

public class PDFConverter {

    private static final MediaType JSON
            = MediaType.get("application/json; charset=utf-8");

    private static OkHttpClient client = new OkHttpClient();

    static byte[] convert(String apiKey, JSONObject params, String endpoint) throws IOException {
        if (!endpoint.equals("pdf") && !endpoint.equals("png") && !endpoint.equals("jpg") && !endpoint.equals("webp")) {
            throw new IllegalArgumentException("Invalid endpoint");

        String url = "" + endpoint;

        RequestBody body = RequestBody.create(params.toString(), JSON);
        Request request = new Request.Builder()
                .addHeader("Authorization", "Basic " + java.util.Base64.getEncoder().encodeToString(("api:" + apiKey).getBytes()))
        Response response = client.newCall(request).execute();

        if (!response.isSuccessful()) {
            throw new IOException("Unexpected code " + response);

        if (params.has("filename") || params.has("webhook")) {
            // Return in JSON in this case
            return new Gson().fromJson(new String(response.body().bytes()), JsonObject.class).toString().getBytes();

        // Returns the bytes
        return response.body().bytes();

Here's how you can use the above code:

public static void main(String[] args) throws IOException {
    JSONObject params = new JSONObject();
    params.put("source", "");
    byte[] binary = convert("sk_XXXXXXXXXXXXXX", params, "pdf");
    Files.write(Paths.get("result.pdf"), binary);

We've tested this code with the latest version of Retrofit and it's ready to be used in your project.

But if you were to encounter any bugs or issues while running it (or if you want to suggest changes to improve the code), please contact us and we'll be happy to help you out.