netty核心源码一 ChannelPipeline

最新推荐文章于 2025-06-22 08:01:05 发布

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本文详细解析了Netty框架中ChannelPipeline的工作原理，包括读写操作流程及涉及的关键方法，为开发者深入理解Netty提供了清晰的指导。

说到channelPipeline 我们下载netty源码，先看其接口定义，再看具体的实现

通过前面的例子，我们知道addLast方法之类的可以注册一些channelHandler,今天我们来看下具体的实现原理

先看官方提供的视图

 * <pre>
 *                                                 I/O Request
 *                                            via {@link Channel} or
 *                                        {@link ChannelHandlerContext}
 *                                                      |
 *  +---------------------------------------------------+---------------+
 *  |                           ChannelPipeline         |               |
 *  |                                                  \|/              |
 *  |    +----------------------------------------------+----------+    |
 *  |    |                   ChannelHandler  N                     |    |
 *  |    +----------+-----------------------------------+----------+    |
 *  |              /|\                                  |               |
 *  |               |                                  \|/              |
 *  |    +----------+-----------------------------------+----------+    |
 *  |    |                   ChannelHandler N-1                    |    |
 *  |    +----------+-----------------------------------+----------+    |
 *  |              /|\                                  .               |
 *  |               .                                   .               |
 *  | ChannelHandlerContext.fireIN_EVT() ChannelHandlerContext.OUT_EVT()|
 *  |          [method call]                      [method call]         |
 *  |               .                                   .               |
 *  |               .                                  \|/              |
 *  |    +----------+-----------------------------------+----------+    |
 *  |    |                   ChannelHandler  2                     |    |
 *  |    +----------+-----------------------------------+----------+    |
 *  |              /|\                                  |               |
 *  |               |                                  \|/              |
 *  |    +----------+-----------------------------------+----------+    |
 *  |    |                   ChannelHandler  1                     |    |
 *  |    +----------+-----------------------------------+----------+    |
 *  |              /|\                                  |               |
 *  +---------------+-----------------------------------+---------------+
 *                  |                                  \|/
 *  +---------------+-----------------------------------+---------------+
 *  |               |                                   |               |
 *  |       [ Socket.read() ]                    [ Socket.write() ]     |
 *  |                                                                   |
 *  |  Netty Internal I/O Threads (Transport Implementation)            |
 *  +-------------------------------------------------------------------+
 * </pre>

上面这个流程图，左边的线路表示读取，socket.read, 也就是从服务端接受到请求之后的处理过程。

会涉及到哪些方法呢？如下图

 <li>Inbound event propagation methods:
 *     <ul>
 *     <li>{@link ChannelHandlerContext#fireChannelRegistered()}</li>
 *     <li>{@link ChannelHandlerContext#fireChannelActive()}</li>
 *     <li>{@link ChannelHandlerContext#fireChannelRead(Object)}</li>
 *     <li>{@link ChannelHandlerContext#fireChannelReadComplete()}</li>
 *     <li>{@link ChannelHandlerContext#fireExceptionCaught(Throwable)}</li>
 *     <li>{@link ChannelHandlerContext#fireUserEventTriggered(Object)}</li>
 *     <li>{@link ChannelHandlerContext#fireChannelWritabilityChanged()}</li>
 *     <li>{@link ChannelHandlerContext#fireChannelInactive()}</li>
 *     </ul>
 * </li>

右边的线路表示，socket.write

 * <li>Outbound event propagation methods:
 *     <ul>
 *     <li>{@link ChannelHandlerContext#bind(SocketAddress, ChannelPromise)}</li>
 *     <li>{@link ChannelHandlerContext#connect(SocketAddress, SocketAddress, ChannelPromise)}</li>
 *     <li>{@link ChannelHandlerContext#write(Object, ChannelPromise)}</li>
 *     <li>{@link ChannelHandlerContext#flush()}</li>
 *     <li>{@link ChannelHandlerContext#read()}</li>
 *     <li>{@link ChannelHandlerContext#disconnect(ChannelPromise)}</li>
 *     <li>{@link ChannelHandlerContext#close(ChannelPromise)}</li>
 *     </ul>
 * </li>