Descargar archivos de Internet con Java

<!-- https://mvnrepository.com/artifact/org.asynchttpclient/async-http-client -->
<dependency>
    <groupId>org.asynchttpclient</groupId>
    <artifactId>async-http-client</artifactId>
    <version>2.10.4</version>
</dependency>

https://thumbs.gfycat.com/TepidLinearCollie-size_restricted.gif

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.concurrent.ExecutionException;
import org.asynchttpclient.Dsl;
import org.asynchttpclient.AsyncCompletionHandler;
import org.asynchttpclient.AsyncHandler;
import org.asynchttpclient.AsyncHttpClient;
import org.asynchttpclient.HttpResponseBodyPart;
import org.asynchttpclient.Response;

/**
 * @see https://www.jc-mouse.net/
 * @author mouse
 */
public class Main {

    public static void main(String[] args) {
        try {
            //archivo a descargar
            final String ORIGEN = "https://thumbs.gfycat.com/TepidLinearCollie-size_restricted.gif";
            //archivo destino
            final String DESTINO = "archivo_descargado.gif";

            FileOutputStream stream = new FileOutputStream(DESTINO);

            AsyncHttpClient client = Dsl.asyncHttpClient();

            AsyncCompletionHandler<FileOutputStream> asyncHandler = new AsyncCompletionHandler<FileOutputStream>() {
                @Override
                public AsyncHandler.State onBodyPartReceived(HttpResponseBodyPart bodyPart)
                        throws Exception {
                    System.out.println("onBodyPartReceived LEN:" + bodyPart.length() + " bytes | Ultima parte: " + bodyPart.isLast());
                    //escribe en archivo parte por parte                   
                    stream.getChannel().write(bodyPart.getBodyByteBuffer());
                    return AsyncHandler.State.CONTINUE;
                }

                @Override
                public FileOutputStream onCompleted(Response response)
                        throws Exception {
                    System.out.println("Descarga completa");
                    return stream;
                }
            };

            FileOutputStream fos = client.prepareGet(ORIGEN).execute(asyncHandler).get();
            fos.close();
        } catch (FileNotFoundException ex) {
            System.err.println(ex.getMessage());
        } catch (InterruptedException | ExecutionException | IOException ex) {
            System.err.println(ex.getMessage());
        }

    }

}