Netty创建连接

执行channel.read也就是AbstractChannel#read

注册到workerGroup，执行方法register

pipeline.read

read:unsafe.beginRead();默认实现在AbstractUnsafe的beginRead中

是否首次连接

processSelectKeyOptimized

如果channel处于激活状态

pipeline.fireChannelActive传播渠道Active事件

Handler3(是否实现read)

unsafe.read开始读

NioEventLoop.run

HeadContext的ChannelActive方法

开始channelRead传播

register0

HeadContext的read方法

Handler2(是否实现read)

server侧的unsafe其实是AbstractNioMessageUnsafe

TailContext(没有实现read)

Pipeline

是

Worker Group线程组

ServerBootstrapAcceptor

doRegister模板方法，这个就是JDK式的注册

1.封装JDK的SocketChannel产生NioSocketChannel

readIfIsAutoRead

实现逻辑如下图注册读事件的图中

    注册读事件@Override    protected void doBeginRead() throws Exception {        // Channel.read() or ChannelHandlerContext.read() was called        final SelectionKey selectionKey = this.selectionKey;        if (!selectionKey.isValid()) {            return;        }        readPending = true;        final int interestOps = selectionKey.interestOps();        if ((interestOps & readInterestOp) == 0) {            selectionKey.interestOps(interestOps | readInterestOp);        }    }

执行AbstractNioChannel下的AbstractUnsafe内的register

有连接请求进入

Handler1(是否实现read)

Server(NioServerSocketChannel)