java - netty echo 服务器发送消息，但我没有看到它

Question

我正在阅读默认手册 link我遇到了一个问题。我的回显服务器向客户端发送消息，但我没有看到它们。作为远程登录程序，我使用腻子。代码是一样的:

public class DiscardServerHandler extends ChannelInboundHandlerAdapter { // (1)

@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) { // (2)
    ChannelFuture cf = ctx.write(msg);
    ctx.flush();
    if (!cf.isSuccess()) {
        System.out.println("Send failed: " + cf.cause());
    }else{
        System.out.println("Send worked.");
    }
}

@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) { // (4)
    // Close the connection when an exception is raised.
    cause.printStackTrace();
    ctx.close();
}
}

第二类:

public class DiscardServer {

private int port;

public DiscardServer(int port) {
    this.port = port;
}

public void run() throws Exception {
    EventLoopGroup bossGroup = new NioEventLoopGroup(); // (1)
    EventLoopGroup workerGroup = new NioEventLoopGroup();
    try {
        ServerBootstrap b = new ServerBootstrap(); // (2)
        b.group(bossGroup, workerGroup)
                .channel(NioServerSocketChannel.class) // (3)
                .childHandler(new ChannelInitializer<SocketChannel>() { // (4)
                    @Override
                    public void initChannel(SocketChannel ch) throws Exception {
                        ch.pipeline().addLast(new DiscardServerHandler());
                    }
                })
                .option(ChannelOption.SO_BACKLOG, 128)          // (5)
                .childOption(ChannelOption.SO_KEEPALIVE, true); // (6)

        // Bind and start to accept incoming connections.
        ChannelFuture f = b.bind(port).sync(); // (7)

        // Wait until the server socket is closed.
        // In this example, this does not happen, but you can do that to gracefully
        // shut down your server.
        f.channel().closeFuture().sync();
    } finally {
        workerGroup.shutdownGracefully();
        bossGroup.shutdownGracefully();
    }
}

public static void main(String[] args) throws Exception {
    int port;
    if (args.length > 0) {
        port = Integer.parseInt(args[0]);
    } else {
        port = 8080;
    }
    new DiscardServer(port).run();
}
}

cf.isSuccess() 是正确的，但在控制台 (putty) 中，我没有看到任何东西。如果我只想发送文本

ctx.writeAndFlush(Unpooled.copiedBuffer("Netty MAY rock!", CharsetUtil.UTF_8));

• 它有效。但是，如果我尝试发送“msg”——我什么也得不到。预先感谢您的回复。

Answer 1

要读取和写入非 ByteBuf 消息，您需要解码器和编码器。

ch.pipeline().addLast(new LineBasedFrameDecoder(80))
                    .addLast(new StringDecoder())
                    .addLast(new StringEncoder())
                    .addLast(new DiscardServerHandler());

或者您可以手动解码和编码消息。将String编码成ByteBuf

ctx.writeAndFlush(Unpooled.copiedBuffer("Netty MAY rock!", CharsetUtil.UTF_8));