javaIO复制文件有关问题

public static void main(String[] args) {        long startTime = System.nanoTime();        try {        File file = new File("F:\\old.gif");        File newfile = new File("F:\\new.gif");        FileInputStream in = new FileInputStream(file);        FileOutputStream out = new FileOutputStream(newfile);        byte[] b = new byte[1024];        while(in.read(b,0,1024)!=-1){            out.write(b,0,1024);        }        in.close();        out.close();        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e){            e.printStackTrace();        }        long time = System.nanoTime()-startTime;        System.out.println(time/(1000*1000)+"ms");    }