# 什么是NIO

## 什么是NIO

Java NIO(New IO)是一个可以替代标准Java IO API的IO API（从Java 1.4开始)，也可以说成非阻塞式I/O.

## Java NIO提供了与标准IO不同的IO工作方式

**Java NIO: Channels and Buffers（通道和缓冲区）**

标准的IO基于字节流和字符流进行操作的，而NIO是基于通道（Channel）和缓冲区（Buffer）进行操作，数据总是从通道读取到缓冲区中，或者从缓冲区写入到通道中。

**Java NIO: Non-blocking IO（非阻塞IO）**

Java NIO可以让你非阻塞的使用IO，例如：当线程从通道读取数据到缓冲区时，线程还是可以进行其他事情。当数据被写入到缓冲区时，线程可以继续处理它。从缓冲区写入通道也类似。

**Java NIO: Selectors（选择器）**

Java NIO引入了选择器的概念，选择器用于监听多个通道的事件（比如：连接打开，数据到达）。因此，单个的线程可以监听多个数据通道。


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