public class IOStream {
    public static void main(String[] args) throws IOException {
        //目標文件大小：43.9M
        Original ();//使用自建緩沖區方式復制文件耗時148毫秒
        Buff (); //使用包裝流復制文件耗時2727毫秒
        Utils ();//使用工具類復制文件耗時104毫秒
    }
    //使用自建緩沖區方式復制文件
    private static void Original() throws IOException {

        File file = new File ("source.mp4");
        InputStream in  = new FileInputStream (file);
        OutputStream out = new FileOutputStream ("/Users/Shared/a.mp4");

        long startTime = System.currentTimeMillis ();

        byte[] arr = new byte[8192];
        int len;
        while ((len = in.read (arr) )!= -1){
            out.write (arr);
        }

        long endTime = System.currentTimeMillis ();
        System.out.println (endTime-startTime);

        in.close ();
        out.close ();
    }
    //使用包裝流方式復制文件
    private static void Buff() throws IOException {
        File file = new File ("source.mp4");
        InputStream in  = new FileInputStream (file);
        BufferedInputStream bfi= new BufferedInputStream (in);
        OutputStream out = new FileOutputStream ("/Users/Shared/b.mp4");
        BufferedOutputStream bfo = new BufferedOutputStream (out);

        long startTime = System.currentTimeMillis ();

        int len;
        while ((len = bfi.read () )!= -1){
            bfo.write (len);
        }

        long endTime = System.currentTimeMillis ();
        System.out.println (endTime-startTime);

        bfi.close ();
        bfo.close ();
    }

    //使用工具包復制文件
    private static void Utils() throws IOException {

        File file1 = new File ("source.mp4");//文件大小：43.9M
        File file2 = new File ("/Users/Shared/c.mp4");

        long startTime = System.currentTimeMillis ();

        FileUtils.copyFile (file1,file2);

        long endTime = System.currentTimeMillis ();
        System.out.println (endTime-startTime);
    }
}

字節流的三種操作方法效率對比