本文仅适用与Netty4.0.32版本，其他版本是否适用表示并不清楚...
Netty服务器启动流程：
1、创建线程池
创建处理连接的线程池:bossGroup
创建处理所有事件的线程池:workerGroup
???EventLoopGroup bossGroup = new NioEventLoopGroup(); ???EventLoopGroup workerGroup = new NioEventLoopGroup();
2、设定辅助启动类。ServerBootStrap
传入1中开辟的线程池
指定连接该服务器的channel类型
指定需要执行的childHandler
设置部分参数，如AdaptiveRecvByteBufAllocator缓存大小
.Option用于设置bossGroup相关参数
.childOption用于设置workerGroup相关参数
2.5、此处可处理一个问题：超长字符串在服务端handler无法被一次接收完
可通过此句进行设置：.childOption(ChannelOption.RCVBUF_ALLOCATOR, new AdaptiveRecvByteBufAllocator(64, MAX_LENGTH_OF_MSG, 65536))
???ServerBootstrap serverBootstrap = new ServerBootstrap(); ???serverBootstrap.group(bossGroup, workerGroup) ???.channel(NioServerSocketChannel.class)//设置channel类型 ???.childOption(ChannelOption.RCVBUF_ALLOCATOR, new AdaptiveRecvByteBufAllocator(64, MAX_LENGTH_OF_MSG, 65536)) ???.childHandler(new childChannelHandler());//选择执行handler
此处的MAX_LENGTH_OF_MSG必须为2的次幂，不然肯定不会是你设置的那个值，具体会变成什么，源码还没看，等看了再补充...
2.75、构建Handler处理流程
样例如下：
public class childChannelHandler extends ChannelInitializer<SocketChannel>{ ???????@Override ???????protected void initChannel(SocketChannel ch) throws Exception { ???????????//TODO 添加各种功能handler 消息加解密，消息规范检测，构建返回码 ???????????ch.pipeline().addLast(new NettyServerHandler()); ???????} ???}当要添加多个handler时，就必须注意添加的顺序。
这里的handler分为两种类型：
一种继承ChannelInboundHandler，用于处理来自客户端的消息，比如对客户端的消息进行解码，读取等等。该类型在pipeline中的执行顺序与添加顺序一致。
一种继承ChannelOutboundHandler，用于处理即将发往客户端的消息，比如对该消息进行编辑，编码等等。该类型在pipeline中的执行顺序与添加顺序相反。
而且ChannelOutboundHandler的所有handler，放在ChannelInboundHandler下面是执行不到的。
比如：
public class childChannelHandler extends ChannelInitializer<SocketChannel>{ ???????@Override ???????public void initChannel(SocketChannel ch) throws Exception { ???????????ch.pipeline().addLast(new OutboundHandler1()); //handler1 ???????????ch.pipeline().addLast(new OutboundHandler2()); //handler2 ???????????ch.pipeline().addLast(new InboundHandler1()); //handler3 ???????????ch.pipeline().addLast(new InboundHandler2()); //handler4 ???????} ???}以上4个handler的实际执行顺序分别为handler3 -> handler4 -> handler2 ->handler1
如果在handler4下方加上OutboundHandler3，那么这个handler是不会被执行到的。
3、同步等待绑定指定端口
此处可多次执行bind语句绑定多个端口
???ChannelFuture channelFuture = serverBootstrap.bind(8080).sync(); ???channelFuture = serverBootstrap.bind(8081).sync(); ???... ???
4、同步等待服务器关闭信息
channelFuture.channel().closeFuture().sync();
5、最后关闭此前开辟的两个线程池
bossGroup.shutdownGracefully(); workerGroup.shutdownGracefully();
最后整段服务器代码如下：
package Netty;import io.netty.bootstrap.ServerBootstrap;import io.netty.channel.ChannelFuture;import io.netty.channel.ChannelInitializer;import io.netty.channel.ChannelOption;import io.netty.channel.EventLoopGroup;import io.netty.channel.nio.NioEventLoopGroup;import io.netty.channel.socket.SocketChannel;import io.netty.channel.socket.nio.NioServerSocketChannel;import io.netty.channel.AdaptiveRecvByteBufAllocator;public class NettyServer { ???public void startServerInPort(int port) throws Exception{ ???????EventLoopGroup bossGroup = new NioEventLoopGroup(); ???????EventLoopGroup workerGroup = new NioEventLoopGroup(); ???????try{ ???????????//设置启动辅助类 ???????????ServerBootstrap serverBootstrap = new ServerBootstrap(); ???????????serverBootstrap.group(bossGroup, workerGroup) ???????????.channel(NioServerSocketChannel.class)//设置channel类型 ???????????.childOption(ChannelOption.RCVBUF_ALLOCATOR, new AdaptiveRecvByteBufAllocator(64, 2048, 65536)) ???????????.childHandler(new childChannelHandler());//选择执行handler ???????????????????????//阻塞等待服务器完全启动 ???????????ChannelFuture channelFuture = serverBootstrap.bind(port).sync(); ???????????????????????channelFuture.channel().closeFuture().sync(); ???????}finally{ ???????????bossGroup.shutdownGracefully(); ???????????workerGroup.shutdownGracefully(); ???????} ???} ???public class childChannelHandler extends ChannelInitializer<SocketChannel>{ ???????@Override ???????protected void initChannel(SocketChannel ch) throws Exception { ???????????//TODO 添加各种功能handler 消息加解密，消息规范检测，构建返回码 ???????????ch.pipeline().addLast(new NettyServerHandler()); ???????} ???}}客户端的这部分代码和服务器端差不多，就不另开一文啰嗦了。之间贴代码：
import io.netty.bootstrap.Bootstrap;import io.netty.channel.ChannelFuture;import io.netty.channel.ChannelInitializer;import io.netty.channel.ChannelOption;import io.netty.channel.EventLoopGroup;import io.netty.channel.nio.NioEventLoopGroup;import io.netty.channel.socket.SocketChannel;import io.netty.channel.socket.nio.NioSocketChannel;public class NettyClient { ???????public void sendMsgToServer() throws Exception{ ???????EventLoopGroup group = new NioEventLoopGroup(); ???????try{ ???????????//设置辅助启动类信息 ???????????Bootstrap bootstrap = new Bootstrap(); ???????????bootstrap.group(group) ???????????.channel(NioSocketChannel.class)//选择channel类型 ???????????.option(ChannelOption.TCP_NODELAY, true) ???????????.handler(new childChannelHandler()); ???????????????????????//阻塞等待成功连接服务器 ???????????ChannelFuture channelFuture = bootstrap.connect(localhost,8000).sync(); ???????????????????????//阻塞等待来自服务器的处理结果 ???????????channelFuture.channel().closeFuture().sync(); ???????}finally{ ???????????group.shutdownGracefully(); ???????} ???} ???????private class childChannelHandler extends ChannelInitializer<SocketChannel>{ ???????@Override ???????protected void initChannel(SocketChannel ch) throws Exception { ???????????//TODO 添加其他功能处理Handler，如消息加解密 ???????????ch.pipeline().addLast(new NettyClientHandler()); ???????} ???}}Netty从没听过到入门 -- 服务器端详解
原文地址：https://www.cnblogs.com/blackshine/p/9003936.html