【Netty】服务端和客户端

private void start() throws Exception {
 final EchoServerHandler serverHandler = new EchoServerHandler();
 /**
         * NioEventLoop并不是一个纯粹的I/O线程，它除了负责I/O的读写之外
         * 创建了两个NioEventLoopGroup，
         * 它们实际是两个独立的Reactor线程池。
         * 一个用于接收客户端的TCP连接，
         * 另一个用于处理I/O相关的读写操作，或者执行系统Task、定时任务Task等。
         */
 EventLoopGroup bossGroup = new NioEventLoopGroup();
 EventLoopGroup childGroup = new NioEventLoopGroup();
 try {
 //ServerBootstrap负责初始化netty服务器，并且开始监听端口的socket请求
 ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, childGroup)
 .channel(NioServerSocketChannel.class)
 .localAddress(new InetSocketAddress(port))
 .childHandler(new ChannelInitializer<SocketChannel>() {
 @Override
 protected void initChannel(SocketChannel socketChannel) throws Exception {
//                            为监听客户端read/write事件的Channel添加用户自定义的ChannelHandler
                            socketChannel.pipeline().addLast(serverHandler);
 }
 });
 ChannelFuture f = b.bind().sync();
            f.channel().closeFuture().sync();
 } catch (InterruptedException e) {
            e.printStackTrace();
 } finally {
            bossGroup.shutdownGracefully().sync();
            childGroup.shutdownGracefully().sync();
 }
 }

 @Override
 void init(Channel channel) throws Exception {
 final Map<ChannelOption<?>, Object> options = options0();
 synchronized (options) {
            setChannelOptions(channel, options, logger);
 }
 final Map<AttributeKey<?>, Object> attrs = attrs0();
 synchronized (attrs) {
 for (Entry<AttributeKey<?>, Object> e: attrs.entrySet()) {
 @SuppressWarnings("unchecked")
 AttributeKey<Object> key = (AttributeKey<Object>) e.getKey();
                channel.attr(key).set(e.getValue());
 }
 }
 ChannelPipeline p = channel.pipeline();
 final EventLoopGroup currentChildGroup = childGroup;
 final ChannelHandler currentChildHandler = childHandler;
 final Entry<ChannelOption<?>, Object>[] currentChildOptions;
 final Entry<AttributeKey<?>, Object>[] currentChildAttrs;
 synchronized (childOptions) {
            currentChildOptions = childOptions.entrySet().toArray(newOptionArray(0));
 }
 synchronized (childAttrs) {
            currentChildAttrs = childAttrs.entrySet().toArray(newAttrArray(0));
 }
        p.addLast(new ChannelInitializer<Channel>() {
 @Override
 public void initChannel(final Channel ch) throws Exception {
 final ChannelPipeline pipeline = ch.pipeline();
 ChannelHandler handler = config.handler();
 if (handler != null) {
                    pipeline.addLast(handler);
 }
                ch.eventLoop().execute(new Runnable() {
 @Override
 public void run() {
                        pipeline.addLast(new ServerBootstrapAcceptor(
                                ch, currentChildGroup, currentChildHandler, currentChildOptions, currentChildAttrs));
 }
 });
 }
 });
 }

 private void start() throws Exception {
 /**
         * Netty用于接收客户端请求的线程池职责如下。
         * （1）接收客户端TCP连接，初始化Channel参数；
         * （2）将链路状态变更事件通知给ChannelPipeline
         */
 EventLoopGroup group = new NioEventLoopGroup();
 try {
 Bootstrap b = new Bootstrap();
            b.group(group)
 .channel(NioSocketChannel.class)
 .remoteAddress(new InetSocketAddress(host,port))
 .handler(new ChannelInitializer<SocketChannel>() {
 @Override
 protected void initChannel(SocketChannel socketChannel) throws Exception {
                            socketChannel.pipeline().addLast(new EchoClientHandler());
 }
 });
 //绑定端口
 ChannelFuture f = b.connect().sync();
            f.channel().closeFuture().sync();
 } catch (Exception e) {
 group.shutdownGracefully().sync();
 }
 }