Download file with HTTP resumable

DownloadUtils.java

import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;
import okhttp3.ResponseBody;
import org.apache.commons.io.IOUtils;

import java.io.*;
import java.net.URL;

public class DownloadUtils {

    OkHttpClient client = new OkHttpClient();

    public void downloadResumable(URL url, File file, int maxTry) throws IOException {
        maxTry = Math.max(maxTry, 1);
        boolean finished = false;

        long contentLength = getUrlContentLength(url);

        while (!finished) {

            long currentLength = getFileLength(file);

            // check current file less than declared size
            if (currentLength >= contentLength) {
                finished = true;
                break;
            }

            boolean isResume = currentLength > 0;

            Request.Builder requestBuilder = new Request.Builder();

            if (isResume) {
                requestBuilder.header("Range", "bytes=" + currentLength + "-");
            }

            Request request = requestBuilder.url(url).build();
            Response response = client.newCall(request).execute();
            ResponseBody body = response.body();

            try (InputStream inputStream = body.byteStream();
                 OutputStream outputStream = new FileOutputStream(file, isResume)) {
                IOUtils.copy(inputStream, outputStream);
                finished = true;
            } catch (IOException ioException) {
                maxTry--;
                if (maxTry <= 0) {
                    throw ioException;
                }
            }
        }

    }

    long getUrlContentLength(URL url) throws IOException {
        Request.Builder requestBuilder = new Request.Builder();
        Request request = requestBuilder.url(url).head().build();
        Response response = client.newCall(request).execute();
        return Long.parseLong(response.header("Content-Length"));
    }

    long getFileLength(File file) {
        return file.exists() ? file.length() : 0;
    }


}