public class FileCopy {    public static void main(String[] args) {        String path = "d:\\1.txt";        String newPath = "d:\\2.txt";        try {            InputStream is = new FileInputStream(path);            OutputStream os = new FileOutputStream(newPath);            int len = 0;            byte[] b = new byte[1024];            while((len = is.read(b)) != -1)                os.write(b,0,len);            os.close();            is.close();        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }    }}

 入出len byte while 关