copyFile.js

// This code is made for Rhino JavaScript engine with Java runtime

const FileInputStream = java.io.FileInputStream,
	FileOutputStream = java.io.FileOutputStream,
	Byte = java.lang.Byte,
	JavaArray = java.lang.reflect.Array;

function copyFile(src, dest) {
	let inputStream, outputStream;
	try {
		inputStream = new FileInputStream(src);
		outputStream = new FileOutputStream(dest);
		let buf = JavaArray.newInstance(Byte.TYPE, 4096), reads;
		while ((reads = inputStream.read(buf)) > 0)
			outputStream.write(buf, 0, reads);
	} catch (e) {
		e.printStackTrace();
	} finally {
		try {
			if (!inputStream) inputStream.close();
			if (!outputStream) outputStream.close();
		} catch (e) {
			e.printStackTrace();
		}
	}
}