Netty实现socket一个客户端对三个服务端的java代码

以下是一个使用Netty实现一个客户端对三个服务端的Java代码示例：

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelHandlerContext;
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;
import java.net.InetSocketAddress;
import java.util.ArrayList;
import java.util.List;

public class MultiServerClient {

    private List<Channel> channels = new ArrayList<>();

    public void connect(String[] serverList) {
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            Bootstrap b = new Bootstrap();
            b.group(group)
                    .channel(NioSocketChannel.class)
                    .option(ChannelOption.TCP_NODELAY, true)
                    .handler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        public void initChannel(SocketChannel ch) throws Exception {
                            ch.pipeline().addLast(new ClientHandler());
                        }
                    });
            for (String server : serverList) {
                String[] addr = server.split(":");
                String host = addr[0];
                int port = Integer.parseInt(addr[1]);
                ChannelFuture f = b.connect(new InetSocketAddress(host, port)).sync();
                channels.add(f.channel());
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public void send(String message) {
        if (!channels.isEmpty()) {
            Channel channel = channels.get(0); // 这里选择第一个 Channel 实例发送数据
            channel.writeAndFlush(message);
        }
    }

    public void close() {
        for (Channel channel : channels) {
            channel.close();
        }
        channels.clear();
    }

    private static class ClientHandler extends ChannelInboundHandlerAdapter {
        @Override
        public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
            // 处理服务端响应的数据
        }
    }

    public static void main(String[] args) {
        MultiServerClient client = new MultiServerClient();
        String[] serverList = {"localhost:8080", "localhost:8081", "localhost:8082"};
        client.connect(serverList);
        client.send("Hello, world!");
        client.close();
    }
}

在`connect()`方法中，循环遍历服务端列表，对于每个服务端，创建一个`InetSocketAddress`实例，然后调用`Bootstrap`的`connect()`方法连接服务端，并将返回的`ChannelFuture`实例中的`Channel`保存到`channels`列表中。

在`send()`方法中，从`channels`列表中选择一个`Channel`实例，通过`writeAndFlush()`方法发送数据。

在`main()`方法中，创建一个`MultiServerClient`实例，传入服务端列表，连接服务端，发送数据，然后关闭连接。