Java NIO

核心组成

Channels
- FileChannel
- DatagramChannel
- SocketChannel
- ServerSocketChannel
Buffers
- ByteBuffer
- CharBuffer
- DoubleBuffer
- FloatBuffer
- IntBuffer
- LongBuffer
- ShortBuffer
```
 数据可以从Channel读到Buffer中，也可以从Buffer 写到Channel中
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Selectors(Selector允许单线程处理多个 Channel)