要通過Netty管理Mybatis的連接池，你需要遵循以下步驟：

1. 引入依賴：確保你的項目中已經引入了Netty和Mybatis的相關依賴。

2. 創建連接池：使用Mybatis提供的SqlSessionFactory創建一個連接池。你可以使用內置的PooledSqlSessionFactory或者自定義一個連接池實現。

import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.apache.ibatis.io.Resources;
import java.io.InputStream;
import java.util.Properties;

public class MybatisUtil {
    private static SqlSessionFactory sqlSessionFactory;

    static {
        try {
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            Properties properties = new Properties();
            properties.load(inputStream);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(properties);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static SqlSessionFactory getSqlSessionFactory() {
        return sqlSessionFactory;
    }
}

3. 創建Netty的ChannelHandler：為了在Netty中使用Mybatis，你需要創建一個自定義的ChannelHandler，用于處理數據庫操作。在這個ChannelHandler中，你可以使用Mybatis的SqlSession來執行SQL語句。

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;

public class MybatisChannelHandler extends ChannelInboundHandlerAdapter {
    private SqlSessionFactory sqlSessionFactory;

    public MybatisChannelHandler(SqlSessionFactory sqlSessionFactory) {
        this.sqlSessionFactory = sqlSessionFactory;
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        // 處理接收到的消息
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        cause.printStackTrace();
        ctx.close();
    }

    public void executeSql(String sql, Object... params) {
        try (SqlSession sqlSession = sqlSessionFactory.openSession()) {
            // 使用SqlSession執行SQL語句
            // 例如：sqlSession.selectOne("com.example.mapper.UserMapper.selectUserById", params);
            sqlSession.close();
        }
    }
}

4. 在Netty服務器中添加ChannelHandler：將你的MybatisChannelHandler添加到Netty服務器的ChannelPipeline中。

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelInitializer;
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.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;

public class NettyServer {
    public static void main(String[] args) throws InterruptedException {
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel ch) {
                            ch.pipeline().addLast(new StringDecoder());
                            ch.pipeline().addLast(new StringEncoder());
                            ch.pipeline().addLast(new MybatisChannelHandler(MybatisUtil.getSqlSessionFactory()));
                        }
                    });

            serverBootstrap.bind(8080).sync().channel().closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

現在，你可以在Netty服務器中使用Mybatis連接池執行SQL語句了。請注意，這個示例僅用于演示目的，實際項目中你可能需要根據需求進行調整。