Netty4源码分析—ServerSocketChannel注册到Selector
public B channel(Class<? extends C> channelClass) { if (channelClass == null) { throw new NullPointerException("channelClass"); } return channelFactory(new BootstrapChannelFactory<C>(channelClass));}

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final ChannelFuture initAndRegister() { final Channel channel = channelFactory().newChannel();//(1) try { init(channel);//(2) } catch (Throwable t) { channel.unsafe().closeForcibly(); return channel.newFailedFuture(t); } ChannelPromise regPromise = channel.newPromise();//(3) group().register(channel, regPromise);//(4) if (regPromise.cause() != null) { if (channel.isRegistered()) { channel.close(); } else { channel.unsafe().closeForcibly(); } } return regPromise; }

private void register0(ChannelPromise promise) { try { // check if the channel is still open as it could be closed in the mean time when the register // call was outside of the eventLoop if (!ensureOpen(promise)) { return; } doRegister(); //将serverchannel注册到selector中 registered = true; promise.setSuccess(); pipeline.fireChannelRegistered(); if (isActive()) { pipeline.fireChannelActive(); } } catch (Throwable t) { // Close the channel directly to avoid FD leak. closeForcibly(); closeFuture.setClosed(); if (!promise.tryFailure(t)) { logger.warn( "Tried to fail the registration promise, but it is complete already. " + "Swallowing the cause of the registration failure:", t); } } }

private static void doBind0( final ChannelFuture regFuture, final Channel channel, final SocketAddress localAddress, final ChannelPromise promise) { // This method is invoked before channelRegistered() is triggered. Give user handlers a chance to set up // the pipeline in its channelRegistered() implementation. channel.eventLoop().execute(new Runnable() { //(1) @Override public void run() { if (regFuture.isSuccess()) { channel.bind(localAddress, promise).addListener(ChannelFutureListener.CLOSE_ON_FAILURE); } else { promise.setFailure(regFuture.cause()); } } });}

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