Напишите поток ввода в файл java

InputStream pdf = // greate some input stream data
try (FileOutputStream outputStream = new FileOutputStream(new File("/Users/kirkbrown/documents/my.pdf"))) {

			int read;
			byte[] bytes = new byte[1024];

			while ((read = pdf.read(bytes)) != -1) {
				outputStream.write(bytes, 0, read);
			}
		}
Kirk-Patrick Brown