不识Netty真面目，只缘未读此真经 (3)

注意：追踪的是当前最新release的 4.1.58.Final 版本的源码。

<dependency> <groupId>io.netty</groupId> <artifactId>netty-all</artifactId> <version>4.1.58.Final</version> </dependency>

本文出自 行无际的博客 ：

https://www.cnblogs.com/itwild/

关键类

下面先重点看几个关键类的大致情况，方便我们读代码 。因为面向抽象编程，如果对常见类的继承层次一点不了解，读代码的过程会让人崩溃。你懂的！！！

NioEventLoopGroup

类定义：

io.netty.channel.nio.NioEventLoopGroup

/** * {@link MultithreadEventLoopGroup} implementations which is used for NIO {@link Selector} based {@link Channel}s. */ public class NioEventLoopGroup extends MultithreadEventLoopGroup

类图：

NioEventLoop

类定义：

io.netty.channel.nio.NioEventLoop

/** * {@link SingleThreadEventLoop} implementation which register the {@link Channel}'s to a * {@link Selector} and so does the multi-plexing of these in the event loop. * */ public final class NioEventLoop extends SingleThreadEventLoop

类图：

NioServerSocketChannel

类定义：

io.netty.channel.socket.nio.NioServerSocketChannel

/** * A {@link io.netty.channel.socket.ServerSocketChannel} implementation which uses * NIO selector based implementation to accept new connections. */ public class NioServerSocketChannel extends AbstractNioMessageChannel implements io.netty.channel.socket.ServerSocketChannel

类图：

NioSocketChannel

类定义：

io.netty.channel.socket.nio.NioSocketChannel

/** * {@link io.netty.channel.socket.SocketChannel} which uses NIO selector based implementation. */ public class NioSocketChannel extends AbstractNioByteChannel implements io.netty.channel.socket.SocketChannel

类图：

ChannelInitializer

类定义：

io.netty.channel.ChannelInitializer

/** * A special {@link ChannelInboundHandler} which offers an easy way to initialize a {@link Channel} once it was * registered to its {@link EventLoop}. * * Implementations are most often used in the context of {@link Bootstrap#handler(ChannelHandler)} , * {@link ServerBootstrap#handler(ChannelHandler)} and {@link ServerBootstrap#childHandler(ChannelHandler)} to * setup the {@link ChannelPipeline} of a {@link Channel}. * * <pre> * * public class MyChannelInitializer extends {@link ChannelInitializer} { * public void initChannel({@link Channel} channel) { * channel.pipeline().addLast("myHandler", new MyHandler()); * } * } * * {@link ServerBootstrap} bootstrap = ...; * ... * bootstrap.childHandler(new MyChannelInitializer()); * ... * </pre> * Be aware that this class is marked as {@link Sharable} and so the implementation must be safe to be re-used. * * @param <C> A sub-type of {@link Channel} */ @Sharable public abstract class ChannelInitializer<C extends Channel> extends ChannelInboundHandlerAdapter