downloadFile.js

const Jsoup = org.jsoup.Jsoup,
	FileOutputStream = java.io.FileOutputStream,
	Byte = java.lang.Byte,
	JavaArray = java.lang.reflect.Array;

// ...

function downloadFile(url, file) {
	let inputStream, outputStream;
	try {
		let execute = Jsoup.connect(url)
				.ignoreHttpErrors(true)
				.ignoreContentType(true)
				.execute();
		inputStream = execute.bodyStream();
		outputStream = new FileOutputStream(file);
		let buf = JavaArray.newInstance(Byte.TYPE, 4096), reads;
		while ((reads = inputStream.read(buf)) > 0)
			outputStream.write(buf, 0, reads);
	} catch (e) {
		Log.e(e.getMessage());
	} finally {
		try {
			if (!inputStream) inputStream.close();
			if (!outputStream) outputStream.close();
		} catch (e) {
			Log.e(e.getMessage());
		}
	}
}