使用非直接缓冲区与直接缓冲区进行文件的复制（基于Channel）

一、利用通道完成文件的复制(非直接缓冲区)

   

        long start = System.currentTimeMillis();
        FileInputStream fis = new FileInputStream("g:/29.mp4");
        FileOutputStream fos = new FileOutputStream("g:/30.mp4");
        //获取通道
        FileChannel inChannel = fis.getChannel();
        FileChannel outChannel = fos.getChannel();
        //分配指定大小缓冲区
        ByteBuffer buf = ByteBuffer.allocate(1024);
        //将通道中的数据存入缓冲区
        while (inChannel.read(buf) != -1){
            buf.flip();
            //将缓冲区的数据写入到通道中
            outChannel.write(buf);
            buf.clear();//清空缓冲区
        }
        outChannel.close();
        inChannel.close();
        fis.close();
        fos.close();

        long end = System.currentTimeMillis();
        System.out.println("消耗的时间为：" + (end - start));//3231

二 、使用直接缓冲区完成文件的复制（内存映射）

         

        long start = System.currentTimeMillis();
        FileChannel inChannel = FileChannel.open(Paths.get("g:/29.mp4"), StandardOpenOption.READ);
        FileChannel outChannel = FileChannel.open(Paths.get("g:/30.mp4"), StandardOpenOption.WRITE,StandardOpenOption.READ, StandardOpenOption.CREATE);

        //内存映射文件
        MappedByteBuffer inMappedBuf = inChannel.map(FileChannel.MapMode.READ_ONLY,0,inChannel.size());
        MappedByteBuffer outMappedBuf = outChannel.map(FileChannel.MapMode.READ_WRITE,0,inChannel.size());

        //直接对缓冲区进行数据的读写操作
        byte[] dst = new byte[inMappedBuf.limit()];
        inMappedBuf.get(dst);
        outMappedBuf.put(dst);

        inChannel.close();
        outChannel.close();

        long  end = System.currentTimeMillis();
        System.out.println("消耗的时间为：" + (end - start));//522