Netty 连接池不向服务器发送消息

Question

我有一个简单的 netty 连接池和一个简单的 HTTP 端点，可以使用该池将 TCP 消息发送到 ServerSocket。相关代码如下所示，客户端（NettyConnectionPoolClientApplication）是：

@SpringBootApplication
@RestController
public class NettyConnectionPoolClientApplication {

  private SimpleChannelPool simpleChannelPool;

  public static void main(String[] args) {
    SpringApplication.run(NettyConnectionPoolClientApplication.class, args);
  }

  @PostConstruct
  public void setup() throws Exception {
    EventLoopGroup group = new NioEventLoopGroup();
    Bootstrap bootstrap = new Bootstrap();

    bootstrap.group(group);
    bootstrap.channel(NioSocketChannel.class);
    bootstrap.option(ChannelOption.SO_KEEPALIVE, true);
    bootstrap.remoteAddress(new InetSocketAddress("localhost", 9000));
    bootstrap.handler(new ChannelInitializer<SocketChannel>() {
      protected void initChannel(SocketChannel socketChannel) throws Exception {
        ChannelPipeline pipeline = socketChannel.pipeline();
        pipeline.addLast(new DelimiterBasedFrameDecoder(8192, Delimiters.lineDelimiter()));
        pipeline.addLast(new StringDecoder());
        pipeline.addLast(new StringEncoder());
        pipeline.addLast(new DummyClientHandler());
      }
    });
    simpleChannelPool = new SimpleChannelPool(bootstrap, new DummyChannelPoolHandler());
  }

  @RequestMapping("/test/{msg}")
  public void test(@PathVariable String msg) throws Exception {
    Future<Channel> future = simpleChannelPool.acquire();

    future.addListener((FutureListener<Channel>) f -> {
      if (f.isSuccess()) {
        System.out.println("Connected");
        Channel ch = f.getNow();
        ch.writeAndFlush(msg + System.lineSeparator());

        // Release back to pool
        simpleChannelPool.release(ch);
      } else {
        System.out.println("not successful");
      }
    });
  }
}

和服务器 (ServerSocketRunner)

public class ServerSocketRunner {

  public static void main(String[] args) throws Exception {
    ServerSocket serverSocket = new ServerSocket(9000);
    while (true) {
      Socket socket = serverSocket.accept();

      new Thread(() -> {
        System.out.println("New client connected");
        try (PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
            BufferedReader in = new BufferedReader(
                new InputStreamReader(socket.getInputStream()));) {

          String inputLine, outputLine;
          out.println("Hello client!");

          do {
            inputLine = in.readLine();
            System.out.println("Received: " + inputLine);
          } while (!"bye".equals(inputLine));

          System.out.println("Closing connection...");
          socket.close();
        } catch (Exception e) {
          e.printStackTrace();
        }
      }).start();
    }
  }
}

DummyChannelPoolHandler and DummyClientHandler 只是打印出发生的事件，所以它们是不相关的。当服务器和客户端启动并且我向测试端点发送测试消息时，我可以看到服务器打印 "New client connected" 但客户端发送的消息未打印。 None 个客户端发送的连续消息被服务器打印出来。

如果我尝试 telnet，一切正常，服务器会打印出消息。它也适用于具有相同 bootstrap 配置且没有连接池 (SimpleNettyClientApplication) 的常规 netty 客户端。

谁能看看我的连接池有什么问题，我没主意了

Netty 版本：4.1.39.Final

所有代码都可用here。

更新

听从 Norman Maurer 的建议。我添加了

ChannelFuture channelFuture = ch
    .writeAndFlush(msg + System.lineSeparator());

channelFuture.addListener(writeFuture -> {
  System.out
      .println("isSuccess(): " + channelFuture.isSuccess() + " : " + channelFuture.cause());
});

这会打印出来

isSuccess: false : java.lang.UnsupportedOperationException: unsupported message type: String (expected: ByteBuf, FileRegion)

为了修复它，我只是将 String 转换为 ByteBuf

ch.writeAndFlush(Unpooled.wrappedBuffer((msg + System.lineSeparator()).getBytes()));

Answer 1

您应该检查 writeAndFlush(...) 返回的 ChannelFuture 的状态。我怀疑它失败了。

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