netty 客户端代码

下面是一个简单的 Netty 客户端代码示例：

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;

public class NettyClient {
    private final String host;
    private final int port;

    public NettyClient(String host, int port) {
        this.host = host;
        this.port = port;
    }

    public void run() throws Exception {
        Bootstrap bootstrap = new Bootstrap();
        bootstrap.group(new NioEventLoopGroup())
            .channel(NioSocketChannel.class)
            .remoteAddress(new InetSocketAddress(host, port))
            .handler(new ChannelInitializer<SocketChannel>() {
                @Override
                protected void initChannel(SocketChannel ch) throws Exception {
                    ch.pipeline().addLast(new SimpleChannelInboundHandler<String>() {
                        @Override
                        protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
                            System.out.println("Received message: " + msg);
                        }
                    });
                }
            })
            .option(ChannelOption.SO_KEEPALIVE, true);

        ChannelFuture cf = bootstrap.connect().sync();
        cf.channel().closeFuture().sync();
    }

    public static void main(String[] args) throws Exception {
        NettyClient client = new NettyClient("localhost", 8080);
        client.run();
    }
}

这个客户端实现了一个简单的 Netty 客户端，可以连接到指定的主机和端口，并发送消息并接收来自服务器的响应。在上面的代码中，我们使用了 NIO 事件循环组、NioSocketChannel、ChannelInitializer 和 SimpleChannelInboundHandler。在 ChannelInitializer 中，我们添加了一个 SimpleChannelInboundHandler 来处理从服务器接收到的消息。在 main 方法中，我们创建了一个 NettyClient 对象，并调用 run 方法来启动客户端。