Opções CLI

ChromeOptions options = new ChromeOptions();
options.setCapability("gsg:customcap", true);
WebDriver driver = new RemoteWebDriver(new URL("http://localhost:4444"), options);
driver.get("https://selenium.dev");
driver.quit();

options.setCapability("se:downloadsEnabled", true);

{
  "value": {
    "names": [
      "Red-blue-green-channel.jpg"
    ]
  }
}

{
  "value": {
    "filename": "Red-blue-green-channel.jpg",
    "contents": "Base64EncodedStringContentsOfDownloadedFileAsZipGoesHere"
  }
}

curl -X GET "http://localhost:4444/session/90c0149a-2e75-424d-857a-e78734943d4c/se/files"

{
  "value": {
    "names": [
      "Red-blue-green-channel.jpg"
    ]
  }
}

curl -H "Accept: application/json" \
-H "Content-Type: application/json; charset=utf-8" \
-X POST -d '{"name":"Red-blue-green-channel.jpg"}' \
"http://localhost:4444/session/18033434-fa4f-4d11-a7df-9e6d75920e19/se/files"

{
  "value": {
    "filename": "Red-blue-green-channel.jpg",
    "contents": "UEsDBBQACAgIAJpagVYAAAAAAAAAAAAAAAAaAAAAUmVkLWJsAAAAAAAAAAAAUmVkLWJsdWUtZ3JlZW4tY2hhbm5lbC5qcGdQSwUGAAAAAAEAAQBIAAAAcNkAAAAA"
  }
}

import static java.util.Collections.singletonMap;
import static org.openqa.selenium.remote.http.Contents.string;

import java.io.File;
import java.lang.reflect.Type;
import java.net.URL;
import java.util.List;
import java.util.Map;
import java.util.concurrent.TimeUnit;
import org.openqa.selenium.By;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.firefox.FirefoxOptions;
import org.openqa.selenium.io.Zip;
import org.openqa.selenium.json.Json;
import org.openqa.selenium.json.TypeToken;
import org.openqa.selenium.remote.RemoteWebDriver;
import org.openqa.selenium.remote.http.Contents;
import org.openqa.selenium.remote.http.HttpClient;
import org.openqa.selenium.remote.http.HttpMethod;
import org.openqa.selenium.remote.http.HttpRequest;
import org.openqa.selenium.remote.http.HttpResponse;

public class DownloadsSample {

  public static void main(String[] args) throws Exception {
    // Assuming the Grid is running locally.
    URL gridUrl = new URL("http://localhost:4444");
    RemoteWebDriver driver = new RemoteWebDriver(gridUrl, firefoxOptions());
    try {
      demoFileDownloads(driver, gridUrl);
    } finally {
      driver.quit();
    }
  }

  private static void demoFileDownloads(RemoteWebDriver driver, URL gridUrl) throws Exception {
    // Make sure the following directory exists on your machine
    File dirToCopyTo = new File("/usr/downloads/file");
    driver.get("http://the-internet.herokuapp.com/download");
    WebElement element = driver.findElement(By.cssSelector(".example a"));
    element.click();

    // The download happens in a remote Node, which makes it difficult to know when the file
    // has been completely downloaded. For demonstration purposes, this example uses a
    // 10-second sleep which should be enough time for a file to be downloaded.
    // We strongly recommend to avoid hardcoded sleeps, and ideally, to modify your
    // application under test so it offers a way to know when the file has been completely
    // downloaded.
    TimeUnit.SECONDS.sleep(10);

    //This is the endpoint which will provide us with list of files to download and also to
    //let us download a specific file.
    String uri = String.format("/session/%s/se/files", driver.getSessionId());

    String fileToDownload = null;

    try (HttpClient client = HttpClient.Factory.createDefault().createClient(gridUrl)) {
      // To list all files that are were downloaded on the remote node for the current session
      // we trigger GET request.
      HttpRequest request = new HttpRequest(HttpMethod.GET, uri);
      HttpResponse response = client.execute(request);
      String text = string(response);
      Type responseType = new TypeToken<Map<String, Map<String, List<String>>>>() {
      }.getType();
      Map<String, Map<String, List<String>>> map = new Json().toType(text, responseType);
      Map<String, List<String>> parsedResponse = map.get("value");
      for (String eachFile : parsedResponse.get("names")) {
        if (fileToDownload == null) {
          // Let's say there were "n" files downloaded for the current session, we would like
          // to retrieve ONLY the first file.
          fileToDownload = eachFile;
        }
      }
    }
    try (HttpClient client = HttpClient.Factory.createDefault().createClient(gridUrl)) {
      // To retrieve a specific file from one or more files that were downloaded by the current session
      // on a remote node, we use a POST request.

      HttpRequest request = new HttpRequest(HttpMethod.POST, uri);
      request.setContent(Contents.asJson(singletonMap("name", fileToDownload)));
      HttpResponse response = client.execute(request);
      String text = string(response);
      Type responseType = new TypeToken<Map<String, Map<String, String>>>() {
      }.getType();

      Map<String, Map<String, String>> map = new Json().toType(text, responseType);
      Map<String, String> parsedResponse = map.get("value");
      // The returned map would contain 2 keys,
      // filename - This represents the name of the file (same as what was provided by the test)
      // contents - Base64 encoded String which contains the zipped file.
      String encodedContents = parsedResponse.get("contents");

      //The file contents would always be a zip file and has to be unzipped.
      Zip.unzip(encodedContents, dirToCopyTo);
      System.out.println("The file which was "
          + "downloaded in the node is now available in the directory: "
          + dirToCopyTo.getAbsolutePath());
    }
  }

  private static FirefoxOptions firefoxOptions() {
    FirefoxOptions options = new FirefoxOptions();
    // This capability tells the Grid, that this test should be routed ONLY to a node that can
    // auto manage downloads.
    options.setCapability("se:downloadsEnabled", true);
    // Options specific for Firefox to avoid prompting a dialog for downloads. They might
    // change in the future, so please refer to the Firefox documentation for up to date details.
    options.addPreference("browser.download.manager.showWhenStarting", false);
    options.addPreference("browser.helperApps.neverAsk.saveToDisk",
        "images/jpeg, application/pdf, application/octet-stream");
    options.addPreference("pdfjs.disabled", true);
    return options;
  }
}