上文說到了，channelHandler, 顧名思義 handler 處理者
從channelPipeline的定義中看出，channelPipeline是channelHandler的集合
public interface ChannelPipeline extends Iterable<Entry<String, ChannelHandler>>
檢視其接口定義和源碼可以看出
接口方法
分為三類
Handler life cycle methods
Inbound event handler methods
Outbound event handler methods
netty源碼分析 之五 transport(ChannelHandler)接口方法ChannelHandlerAdapterChannelHandlerContext 接着看AbstractChannelHandlerContext ChannelHandlerInvokerSingleThreadEventLoop 
netty源碼分析 之五 transport(ChannelHandler)接口方法ChannelHandlerAdapterChannelHandlerContext 接着看AbstractChannelHandlerContext ChannelHandlerInvokerSingleThreadEventLoop ChannelHandlerAdapter
大多數的handler都繼承它了
netty源碼分析 之五 transport(ChannelHandler)接口方法ChannelHandlerAdapterChannelHandlerContext 接着看AbstractChannelHandlerContext ChannelHandlerInvokerSingleThreadEventLoop ChannelHandlerContext
netty源碼分析 之五 transport(ChannelHandler)接口方法ChannelHandlerAdapterChannelHandlerContext 接着看AbstractChannelHandlerContext ChannelHandlerInvokerSingleThreadEventLoop 接着看AbstractChannelHandlerContext
看其類的核心實作是，invoker
netty源碼分析 之五 transport(ChannelHandler)接口方法ChannelHandlerAdapterChannelHandlerContext 接着看AbstractChannelHandlerContext ChannelHandlerInvokerSingleThreadEventLoop ChannelHandlerInvoker
netty源碼分析 之五 transport(ChannelHandler)接口方法ChannelHandlerAdapterChannelHandlerContext 接着看AbstractChannelHandlerContext ChannelHandlerInvokerSingleThreadEventLoop SingleThreadEventLoop
這個類裡面已經有 DefaultChannelHandlerInvoker
netty源碼分析 之五 transport(ChannelHandler)接口方法ChannelHandlerAdapterChannelHandlerContext 接着看AbstractChannelHandlerContext ChannelHandlerInvokerSingleThreadEventLoop 
