netty案例，netty4.1源码分析篇三《Netty服务端初始化过程以及反射工厂的作用》

private void bing(int port) {
    //配置服务端NIO线程组
    EventLoopGroup parentGroup = new NioEventLoopGroup(); //NioEventLoopGroup extends MultithreadEventLoopGroup Math.max(1, SystemPropertyUtil.getInt("io.netty.eventLoopThreads", NettyRuntime.availableProcessors() * 2));
    EventLoopGroup childGroup = new NioEventLoopGroup();
    try {
        ServerBootstrap b = new ServerBootstrap();
        b.group(parentGroup, childGroup)
                .channel(NioServerSocketChannel.class)    //非阻塞模式
                .option(ChannelOption.SO_BACKLOG, 128)
                .childHandler(new MyChannelInitializer());
        ChannelFuture f = b.bind(port).sync();
        System.out.println("itstack-demo-netty server start done. {关注公众号：bugstack虫洞栈，获取源码}");
        f.channel().closeFuture().sync();
    } catch (InterruptedException e) {
        e.printStackTrace();
    } finally {
        childGroup.shutdownGracefully();
        parentGroup.shutdownGracefully();
    }

}

public interface ServerSocketChannel extends ServerChannel {
    @Override
    ServerSocketChannelConfig config();
    @Override
    InetSocketAddress localAddress();
    @Override
    InetSocketAddress remoteAddress();
}

public ServerBootstrap group(EventLoopGroup parentGroup, EventLoopGroup childGroup) {
    super.group(parentGroup);
    if (childGroup == null) {
        throw new NullPointerException("childGroup");
    }
    if (this.childGroup != null) {
        throw new IllegalStateException("childGroup set already");
    }
    this.childGroup = childGroup;
    return this;
}

public B channel(Class<? extends C> channelClass) {
    if (channelClass == null) {
        throw new NullPointerException("channelClass");
    }
    return channelFactory(new ReflectiveChannelFactory<C>(channelClass));
}

public T newChannel() {
    try {
        return constructor.newInstance();
    } catch (Throwable t) {
        throw new ChannelException("Unable to create Channel from class " + constructor.getDeclaringClass(), t);
    }
}

public <T> B option(ChannelOption<T> option, T value) {
    if (option == null) {
        throw new NullPointerException("option");
    }
    if (value == null) {
        synchronized (options) {
            options.remove(option);
        }
    } else {
        synchronized (options) {
            options.put(option, value);
        }
    }
    return self();
}

public ServerBootstrap childHandler(ChannelHandler childHandler) {
    if (childHandler == null) {
        throw new NullPointerException("childHandler");
    }
    this.childHandler = childHandler;
    return this;
}

b.bind(port).sync();

private ChannelFuture doBind(final SocketAddress localAddress) {
    final ChannelFuture regFuture = initAndRegister();
    final Channel channel = regFuture.channel();
    if (regFuture.cause() != null) {
        return regFuture;
    }

    if (regFuture.isDone()) {
        // At this point we know that the registration was complete and successful.
        ChannelPromise promise = channel.newPromise();
        doBind0(regFuture, channel, localAddress, promise);
        return promise;
    } else {
        // Registration future is almost always fulfilled already, but just in case it's not.
        final PendingRegistrationPromise promise = new PendingRegistrationPromise(channel);
        regFuture.addListener(new ChannelFutureListener() {
            @Override
            public void operationComplete(ChannelFuture future) throws Exception {
                Throwable cause = future.cause();
                if (cause != null) {
                    // Registration on the EventLoop failed so fail the ChannelPromise directly to not cause an
                    // IllegalStateException once we try to access the EventLoop of the Channel.
                    promise.setFailure(cause);
                } else {
                    // Registration was successful, so set the correct executor to use.
                    // See https://github.com/netty/netty/issues/2586
                    promise.registered();

                    doBind0(regFuture, channel, localAddress, promise);
                }
            }
        });
        return promise;
    }
}

private static ServerSocketChannel newSocket(SelectorProvider provider) {
    try {
        /**
         *  Use the {@link SelectorProvider} to open {@link SocketChannel} and so remove condition in
         *  {@link SelectorProvider#provider()} which is called by each ServerSocketChannel.open() otherwise.
         *
         *  See <a href="https://github.com/netty/netty/issues/2308">#2308</a>.
         */
        return provider.openServerSocketChannel();
    } catch (IOException e) {
        throw new ChannelException(
                "Failed to open a server socket.", e);
    }
}

ServerSocketChannelImpl(SelectorProvider sp) throws IOException {
    super(sp);
    this.fd =  Net.serverSocket(true);
    this.fdVal = IOUtil.fdVal(fd);
    this.state = ST_INUSE;
}