一、利用通道完成文件的复制(非直接缓冲区)
1 long start = System.currentTimeMillis(); 2 FileInputStream fis = new FileInputStream("g:/29.mp4"); 3 FileOutputStream fos = new FileOutputStream("g:/30.mp4"); 4 //获取通道 5 FileChannel inChannel = fis.getChannel(); 6 FileChannel outChannel = fos.getChannel(); 7 //分配指定大小缓冲区 8 ByteBuffer buf = ByteBuffer.allocate(1024); 9 //将通道中的数据存入缓冲区 10 while (inChannel.read(buf) != -1){ 11 buf.flip(); 12 //将缓冲区的数据写入到通道中 13 outChannel.write(buf); 14 buf.clear();//清空缓冲区 15 } 16 outChannel.close(); 17 inChannel.close(); 18 fis.close(); 19 fos.close(); 20 21 long end = System.currentTimeMillis(); 22 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）
1 long start = System.currentTimeMillis(); 2 FileChannel inChannel = FileChannel.open(Paths.get("g:/29.mp4"), StandardOpenOption.READ); 3 FileChannel outChannel = FileChannel.open(Paths.get("g:/30.mp4"), StandardOpenOption.WRITE,StandardOpenOption.READ, StandardOpenOption.CREATE); 4 6 //内存映射文件 7 MappedByteBuffer inMappedBuf = inChannel.map(FileChannel.MapMode.READ_ONLY,0,inChannel.size()); 8 MappedByteBuffer outMappedBuf = outChannel.map(FileChannel.MapMode.READ_WRITE,0,inChannel.size()); 9 10 //直接对缓冲区进行数据的读写操作 11 byte[] dst = new byte[inMappedBuf.limit()]; 12 inMappedBuf.get(dst); 13 outMappedBuf.put(dst); 14 15 inChannel.close(); 16 outChannel.close(); 17 18 long end = System.currentTimeMillis(); 19 System.out.println("消耗的时间为：" + (end - start));//522