maven使用的netty版本如下：

		<dependency>
			<groupId>io.netty</groupId>
			<artifactId>netty-all</artifactId>
			<version>4.1.4.Final</version>
		</dependency>

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
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.handler.codec.LengthFieldBasedFrameDecoder;
import io.netty.handler.codec.LengthFieldPrepender;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.util.CharsetUtil;
import util.LogCore;

public class TcpServer {
	private static final String IP = "127.0.0.1";
	private static final int PORT = 9999;
	/** 用於分配處理業務執行緒的執行緒組個數 */
	protected static final int BIZGROUPSIZE = Runtime.getRuntime().availableProcessors() * 2; // 預設
	/** 業務出現執行緒大小 */
	protected static final int BIZTHREADSIZE = 4;
	/*
	 * NioEventLoopGroup實際上就是個執行緒池,
	 * NioEventLoopGroup在後臺啟動了n個NioEventLoop來處理Channel事件,
	 * 每一個NioEventLoop負責處理m個Channel,
	 * NioEventLoopGroup從NioEventLoop數組裡挨個取出NioEventLoop來處理Channel
	 */
	private static final EventLoopGroup bossGroup = new NioEventLoopGroup(BIZGROUPSIZE);
	private static final EventLoopGroup workerGroup = new NioEventLoopGroup(BIZTHREADSIZE);

	protected static void run() throws Exception {
		ServerBootstrap b = new ServerBootstrap();
		b.group(bossGroup, workerGroup);
		b.channel(NioServerSocketChannel.class);
		b.childHandler(new ChannelInitializer<SocketChannel>() {
			@Override
			public void initChannel(SocketChannel ch) throws Exception {
				ChannelPipeline pipeline = ch.pipeline();
				pipeline.addLast("frameDecoder", new LengthFieldBasedFrameDecoder(Integer.MAX_VALUE, 0, 4, 0, 4));
				pipeline.addLast("frameEncoder", new LengthFieldPrepender(4));
				pipeline.addLast("decoder", new StringDecoder(CharsetUtil.UTF_8));
				pipeline.addLast("encoder", new StringEncoder(CharsetUtil.UTF_8));
				pipeline.addLast(new TcpServerHandler());
			}
		});

		b.bind(IP, PORT).sync();
		LogCore.BASE.info("TCP伺服器已啟動");
	}

	protected static void shutdown() {
		workerGroup.shutdownGracefully();
		bossGroup.shutdownGracefully();
	}

	public static void main(String[] args) throws Exception {
		LogCore.BASE.info("啟動TCP伺服器...");
		TcpServer.run();
		// TcpServer.shutdown();
	}
}
 

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import util.LogCore;

public class TcpServerHandler extends SimpleChannelInboundHandler<Object> {

	@Override
	protected void channelRead0(ChannelHandlerContext ctx, Object msg) throws Exception {
		LogCore.BASE.info("SERVER接收到訊息:" + msg);
		ctx.channel().writeAndFlush("server accepted msg:" + msg);
	}

	@Override
	public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
		LogCore.BASE.warn("exceptionCaught!", cause);
		ctx.close();
	}
}
 

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
import io.netty.handler.codec.LengthFieldPrepender;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.util.CharsetUtil;
import util.LogCore;

public class TcpClient {
	public static String HOST = "127.0.0.1";
	public static int PORT = 9999;

	public static Bootstrap bootstrap = getBootstrap();
	public static Channel channel = getChannel(HOST, PORT);

	/**
	 * 初始化Bootstrap
	 */
	public static final Bootstrap getBootstrap() {
		EventLoopGroup group = new NioEventLoopGroup();
		Bootstrap b = new Bootstrap();
		b.group(group).channel(NioSocketChannel.class);
		b.handler(new ChannelInitializer<Channel>() {
			@Override
			protected void initChannel(Channel ch) throws Exception {
				ChannelPipeline pipeline = ch.pipeline();
				pipeline.addLast("frameDecoder", new LengthFieldBasedFrameDecoder(Integer.MAX_VALUE, 0, 4, 0, 4));
				pipeline.addLast("frameEncoder", new LengthFieldPrepender(4));
				pipeline.addLast("decoder", new StringDecoder(CharsetUtil.UTF_8));
				pipeline.addLast("encoder", new StringEncoder(CharsetUtil.UTF_8));
				pipeline.addLast("handler", new TcpClientHandler());
			}
		});
		b.option(ChannelOption.SO_KEEPALIVE, true);
		return b;
	}

	public static final Channel getChannel(String host, int port) {
		Channel channel = null;
		try {
			channel = bootstrap.connect(host, port).sync().channel();
		} catch (Exception e) {
			LogCore.BASE.error("連線Server(IP{},PORT{})失敗", host, port, e);
			return null;
		}
		return channel;
	}

	public static void sendMsg(String msg) throws Exception {
		if (channel != null) {
			channel.writeAndFlush(msg).sync();
		} else {
			LogCore.BASE.warn("訊息傳送失敗,連線尚未建立!");
		}
	}

	public static void main(String[] args) throws Exception {
		try {
			long t0 = System.nanoTime();
			for (int i = 0; i < 100; i++) {
				TcpClient.sendMsg(i + "你好1");
			}
			long t1 = System.nanoTime();
			LogCore.BASE.info("time used:{}", t1 - t0);
		} catch (Exception e) {
			LogCore.BASE.error("main err:", e);
		}
	}
}
 

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import util.LogCore;

public class TcpClientHandler extends SimpleChannelInboundHandler<Object> {

	@Override
	protected void channelRead0(ChannelHandlerContext ctx, Object msg) throws Exception {
		LogCore.BASE.info("client接收到伺服器返回的訊息:" + msg);
	}
}