public void read() {
    //必須是NioEventLoop方法調(diào)用的, 不能通過(guò)外部線程調(diào)用
    assert eventLoop().inEventLoop();
    //服務(wù)端channel的config
    final ChannelConfig config = config();
    //服務(wù)端channel的pipeline
    final ChannelPipeline pipeline = pipeline();
    //處理服務(wù)端接入的速率
    final RecvByteBufAllocator.Handle allocHandle = unsafe().recvBufAllocHandle();
    //設(shè)置配置
    allocHandle.reset(config);
    boolean closed = false;
    Throwable exception = null;
    try {
        try {
            do {
                //創(chuàng)建jdk底層的channel
                //readBuf用于臨時(shí)承載讀到鏈接
                int localRead = doReadMessages(readBuf);
                if (localRead == 0) {
                    break;
                }
                if (localRead < 0) {
                    closed = true;
                    break;
                }
                //分配器將讀到的鏈接進(jìn)行計(jì)數(shù)
                allocHandle.incMessagesRead(localRead);
                //連接數(shù)是否超過(guò)最大值
            } while (allocHandle.continueReading());
        } catch (Throwable t) {
            exception = t;
        }
        int size = readBuf.size();
        //遍歷每一條客戶端連接
        for (int i = 0; i < size; i ++) {
            readPending = false;
            //傳遞事件, 將創(chuàng)建NioSokectChannel進(jìn)行傳遞
            //最終會(huì)調(diào)用ServerBootstrap的內(nèi)部類ServerBootstrapAcceptor的channelRead()方法
            pipeline.fireChannelRead(readBuf.get(i));
        }
        readBuf.clear();
        allocHandle.readComplete();
        pipeline.fireChannelReadComplete();
        //代碼省略
    } finally {
        //代碼省略
    }
}

private final List<Object> readBuf = new ArrayList<Object>();

protected int doReadMessages(List<Object> buf) throws Exception {
    //根據(jù)當(dāng)前jdk底層的serverSocketChannel拿到j(luò)dk底層channel
    SocketChannel ch = javaChannel().accept();
    try {
        if (ch != null) {
            //封裝成一個(gè)NioSokectChannel扔到buf中
            buf.add(new NioSocketChannel(this, ch));
            return 1;
        }
    } catch (Throwable t) {
        //代碼省略
    }
    return 0;
}

public NioSocketChannel(Channel parent, SocketChannel socket) {
    super(parent, socket);
    config = new NioSocketChannelConfig(this, socket.socket());
}

protected AbstractNioByteChannel(Channel parent, SelectableChannel ch) { 
    super(parent, ch, SelectionKey.OP_READ);
}

protected AbstractNioChannel(Channel parent, SelectableChannel ch, int readInterestOp) {
    super(parent);
    this.ch = ch;
    this.readInterestOp = readInterestOp;
    try {
        //設(shè)置為非阻塞
        ch.configureBlocking(false);
    } catch (IOException e) {
        //代碼省略
    }
}

protected AbstractChannel(Channel parent) {
    this.parent = parent;
    id = newId();
    unsafe = newUnsafe();
    pipeline = newChannelPipeline();
}

protected AbstractNioUnsafe newUnsafe() {
    return new NioByteUnsafe();
}

public NioSocketChannel(Channel parent, SocketChannel socket) {
    super(parent, socket);
    config = new NioSocketChannelConfig(this, socket.socket());
}

private NioSocketChannelConfig(NioSocketChannel channel, Socket javaSocket) {
    super(channel, javaSocket);
}

public DefaultSocketChannelConfig(SocketChannel channel, Socket javaSocket) {
    super(channel);
    if (javaSocket == null) {
        throw new NullPointerException("javaSocket");
    }
    //保存當(dāng)前javaSocket
    this.javaSocket = javaSocket;
    //是否禁止Nagle算法
    if (PlatformDependent.canEnableTcpNoDelayByDefault()) {
        try {
            setTcpNoDelay(true);
        } catch (Exception e) {
        }
    }
}

public DefaultChannelConfig(Channel channel) {
    this(channel, new AdaptiveRecvByteBufAllocator());
}