無法使用 socket.recv() 從服務器接收數據

Question

我有一個 python 客戶端，它以 json 格式將一些數據（命名空間、metric_name、時間戳、metric_value、維度）發送到 java 服務器並接收響應。

這是客戶端代碼的一部分：

def _init_socket(self):
    logger.info("initial socket, hostname {}, port {}".format(self.host, self.port))
    client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    address = (self.host, self.port)
    client.connect(address)
    self.client = client

def send_put_metrics_request(self, namespace, metric_name, metric_value, dimensions): 
    try:
        self._init_socket()
        timestamp = int(round(time.time() * 1000))
        send_data = self.convert_to_json(namespace, metric_name, timestamp, metric_value, dimensions)
        self.client.send(bytes(send_data + "\n", encoding=self.encoding))
        self.client.shutdown(socket.SHUT_WR)

        data = self.client.recv(1024)
        print(data)

    finally:
        self.client.close()

在服務器端，我只想將 HelloWorld 返回給客戶端。 這是java服務器代碼的一部分：

    public void start() {
        logger.info("Daemon Server is listening for metrics");

        try (final ServerSocket serverSocket = new ServerSocket()) {
            final int port = 7072;
            serverSocket.bind(new InetSocketAddress(port));

            while (true) {
                final Socket socket = serverSocket.accept();
                threadPool.submit(() -> process(socket));
            }
        } catch (final Exception e) {
            logger.error(Thread.currentThread().getId() + " failed to make a connection to the server socket"
                + e.getMessage());
            throw new ConnectToServerSocketException(Thread.currentThread().getId()
                + " failed to make a connection to the server socket" + e.getMessage());
        } finally {
            threadPool.shutdown();
        }
    }


    protected void process(final Socket socket) {
        final Message message;
        try (final InputStream input = socket.getInputStream()) {
            final OutputStream output = socket.getOutputStream();
            final OutputStreamWriter osw = new OutputStreamWriter(output, "UTF8");
            final PrintWriter writer = new PrintWriter(new BufferedWriter(osw));
            message = objectMapper.readValue(inputStreamToString(input), Message.class);
// pls ignore the below line, it just calls another method to do something
            final String res = forwardMetrics(message);
            logger.info("Thread " + Thread.currentThread().getId() + " processed result: " + res);

            writer.println("HelloWorld"+"\n");
            writer.flush();
            socket.close();
            logger.info("Socket closed")

        } catch (final IOException e) {
            logger.error(e.getMessage());
            logger.error("Daemon server failed to read input from socket");
            throw new ReadFromSocketException("Failed to read input from socket", e);
        }

    }

然后在我啟動服務器並通過客戶端以正確的格式發送請求之后。 我沒有從客戶端得到“HelloWorld”。 打印結果只是b' ' 。 從服務器端的日志來看，它執行所有行，直到套接字關閉。

我想知道為什么沒有打印出來。

Answer 1

不保證客戶端中的socket.recv()會在第一次獲取時返回響應。 我建議你在 while 循環中調用recv()直到它收到None 。