一、通过Channel和Buffer拷贝文件

@Test
public void channelCopyFile() throws IOException {
    FileInputStream fis = new FileInputStream("e:\\老文件.jpg");
    FileChannel fisChannel = fis.getChannel();

    FileOutputStream fos = new FileOutputStream("e:\\新文件.jpg");
    FileChannel channel = fos.getChannel();

    ByteBuffer bf = ByteBuffer.allocate(512);
    // 从老通道循环读取数据
    while (fisChannel.read(bf) != -1) {
        // 反转缓冲区
        bf.flip();
        // 写入新通道
        channel.write(bf);
        bf.clear();
    }
    // 关闭流
    fos.close();
    fis.close();
    System.out.println("over");
}

 

二、transferTo

@Test
    public void TransferTo() throws IOException {
        FileInputStream fis = new FileInputStream("e:\\222.jpg");
        FileChannel fisChannel = fis.getChannel();

        FileOutputStream fos = new FileOutputStream("e:\\新文件.jpg");
        FileChannel channel = fos.getChannel();

        fisChannel.transferTo(0, fisChannel.size(), channel);
        // 关闭流
        fos.close();
        fis.close();
        System.out.println("over");
    }

 

三、transferFrom

 1  @Test
 2     public void transferFrom() throws IOException {
 3         FileInputStream fis = new FileInputStream("e:\\222.jpg");
 4         FileChannel fisChannel = fis.getChannel();
 5 
 6         FileOutputStream fos = new FileOutputStream("e:\\新文件.jpg");
 7         FileChannel channel = fos.getChannel();
 8 
 9         channel.transferFrom(fisChannel, 0, fisChannel.size());
10         // 关闭流
11         fos.close();
12         fis.close();
13         System.out.println("over");
14     }