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Netty框架的基础上，以下是一个客户端和服务器端的实现代码示例

客户端代码：

package netty2;
import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
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.NioSocketChannel;
import java.net.InetSocketAddress;
public class EchoClient {
    public static void main(String[] args) throws Exception {
        int port = 8001;
        final EchoClientHandler clientHandler = new EchoClientHandler();
        EventLoopGroup eventLoopGroup = new NioEventLoopGroup();
        try {
            Bootstrap b = new Bootstrap();
            b.group(eventLoopGroup)
                    .channel(NioSocketChannel.class)
                    .remoteAddress(new InetSocketAddress("localhost", port))
                    .handler(new ChannelInitializer
   
    () {
                        @Override
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
                            socketChannel.pipeline().addLast(clientHandler);
                        }
                    });
            final ChannelFuture f = b.connect();
            f.addListener(new GenericFutureListener
    
     () {
                @Override
                public void operationComplete(Future
     
       future) throws Exception {
                    if (future.isSuccess()) {
                        System.out.println("已经连接到服务器！");
                        ByteBuf byteBuf = Unpooled.copiedBuffer("aaaaaaaaaaaaaaaa", Charset.defaultCharset());
                        ChannelFuture channelFuture = f.channel().writeAndFlush(byteBuf);
                    } else {
                        Throwable throwable = future.cause();
                        throwable.printStackTrace();
                    }
                }
            });
            f.channel().closeFuture().sync();
        } catch (InterruptedException e) {
            eventLoopGroup.shutdownGracefully().sync();
        }
    }
}
     
    
   

服务器端代码：

package netty2;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.buffer.ByteBufAllocator;
import io.netty.channel.ChannelFuture;
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 java.net.InetSocketAddress;
public class EchoServer {
    public static void main(String[] args) throws Exception {
        int port = 8001;
        EchoServerFirstInHandler firstHandler = new EchoServerFirstInHandler();
        EchoServerSecondInHandler secondHandler = new EchoServerSecondInHandler();
        EchoServerOutHandler outHandler = new EchoServerOutHandler();
        EventLoopGroup eventLoopGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(eventLoopGroup)
                    .channel(NioServerSocketChannel.class)
                    .localAddress(new InetSocketAddress(port))
                    .childHandler(new ChannelInitializer
   
    () {
                        @Override
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
                            ChannelPipeline channelPipeline = socketChannel.pipeline();
                            channelPipeline.addFirst(outHandler);
                            channelPipeline.addLast(firstHandler);
                            channelPipeline.addLast(secondHandler);
                        }
                    });
            ChannelFuture f = serverBootstrap.bind().sync();
            f.channel().closeFuture().sync();
        } catch (InterruptedException e) {
            eventLoopGroup.shutdownGracefully().sync();
        }
    }
}
   

辅助处理器类：

package netty2;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.util.CharsetUtil;
import java.nio.charset.Charset;
public class EchoServerOutHandler extends ChannelOutboundHandlerAdapter {
    public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
        System.out.println("EchoServerOutHandler write: " + ((ByteBuf) msg).toString(Charset.defaultCharset()));
        ctx.write(msg, promise);
    }
}

以上代码示例展示了Netty框架在TCP协议中实现Echo协议的客户端和服务器端通信，基于NIO机制，支持非阻塞IO。通过Bootstrap类进行异步连接，采用分段读写的策略，确保高效处理大量数据流量。

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