Java NIO Channel

Channel is a stream kind of representation in NIO. It is a representation of hardware, file, network device or other program.

There are several different channel that loads data differently.

• FileChannel
• DatagramChannel
• SocketChannel
• ServerSocketChannel

Unlike stream object, which can only input or output one at a time. A single Channel object can do both read and write simutanously.

try (RandomAccessFile file = new RandomAccessFile("data.md", "rw");
     FileChannel c = file.getChannel()) {
  final ByteBuffer b = ByteBuffer.allocate(64);
  b.clear();
  System.out.println("Read " + c.read(b));
  b.flip();
  System.out.println("Write " + c.write(b));
}

From the snippet above, we can tell that a single channel object can do both read and write.