java - 第二个套接字写入似乎没有发送到网络

Question

我正在创建一个简单的网络客户端。它读取一个文本文件并将每一行放入网络。在远端，有一个服务器读取传入行并以 CSV 文本行进行响应。

我用于测试的传出文件很简单:

6216448319，理查德·尼克松，登录
6216448319，理查德·尼克松，注销

响应应该是“已登录”。随后是“已注销”。

第一行处理得很好，但尽管第二行似乎已写入套接字，但服务器从未看到传入消息。我已尽力遵循在线文档和各种教程，但我所看到的似乎都没有表现出相同的行为。我错过了什么？

如果我在自己的文件中发送每一行，服务器会正​​确响应。

protected Integer call() {
    LOG.info("Starting spooler for file {}, address {}:{}", spoolFile, ipAddress, port);
    InetAddress server = null;
    try {
        server = InetAddress.getByName(ipAddress);
        LOG.info("IP Address: {}", server.getHostAddress());
    } catch (Exception e) {
        LOG.error("Unknown host: {}", ipAddress, e);
    }
    try (Socket socket = new Socket(server, port);
         BufferedWriter socketWriter = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
         //PrintWriter socketWriter = new PrintWriter(socket.getOutputStream(), true);
         BufferedReader socketReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
         BufferedReader fileReader = new BufferedReader(new InputStreamReader(new FileInputStream(spoolFile)))
    ) {
        // Read the spool file line by line and put it out on the wire.
        String line;
        while ((line = fileReader.readLine()) != null) {
            if (isCancelled()) {
                LOG.error("Spool has been cancelled.");
                break;
            }
            line = line.trim();
            LOG.info("OUT({}): [{}]", line.length(), line);
            //Wait until the channel has successfully written out the line.
            LOG.info("Socket is {} for write.", socket.isConnected() ? "connected" : "not connected");
            socketWriter.write(line);
            socketWriter.flush();
            TalkmanMessage outMessage = new TalkmanMessage(line);
            outMessageList.add(outMessage);
            // Wait for the network to respond.
            // Apparently, readline() blocks until a message is received.
            LOG.info("Waiting for response...");
            LOG.info("Socket is {} for read.", socket.isConnected() ? "connected" : "not connected");
            String msg = socketReader.readLine();
            LOG.info("IN({}): [{}]", msg == null ? null : msg.length(), msg);
            TalkmanMessage inMessage = new TalkmanMessage(msg);
            inMessage.setDelay(
                    Duration.between(outMessage.getTime(), inMessage.getTime()).toNanos());
            inMessageList.add(inMessage);
            //The readline() seems to leave a non-printing byte in the socket. Read that out.
            int leftOver;
            do {
                LOG.info("Socket is {} for EOL", socket.isConnected() ? "connected." : "not connected");
                leftOver = socketReader.read();
                LOG.info("Read {} from socket.", leftOver);
            } while (leftOver > -1);
        }
    } catch (Exception e) {
        LOG.error("Unable to read from file/write to .", e);
    }
    return 1;
}

日志记录命令产生以下输出:

OUT(29): [6216448319,Richard Nixon,Log In] 
Socket is connected for write.
Waiting for response... 
Socket is connected for read. 
IN(12): ["Logged in."]
Socket is connected for EOL 
Read 13 from socket. S
Socket is connected for EOL 
Read 10 from socket. 
Socket is connected for EOL 
Read -1 from socket. 
OUT(30): [6216448319,Richard Nixon,Log Out] 
Socket is connected for write. 
Waiting for response... 
Socket is connected for read. IN(null): [null] 
Socket is connected for EOL 
Read -1 from socket.

Answer 1

1. 您忽略了流结束。一次read()返回-1，连接已关闭。

2. 你不断测试是错误的socket.isConnected() 。它不会神奇地变成假的。这不是对等断开连接的测试。

3. 您确实应该向对方写入行吗？即调用 newLine()发送完每一行后？

4. 事实上，您应该只是复制字节，而不是读取行、删除/恢复行终止符、修剪等。使用流，而不是读取器和写入器。

5. 如果你正在假脱机，为什么你期望每一行都有响应？假脱机的本质是你只需编写。返回的数据(如下)绝不表明它是每行的响应。

6. 您似乎正在尝试阅读 EOL，它已被 newLine() 删除。 。请参阅 Javadoc。这没有道理。而且您还尝试通过在发送的每一行上读取直到流结束来完成此操作，这更没有意义。

7. 服务器向您发送的内容如下:

   IN(12): ["Logged in."]<some line terminator, probably but not certainly CR LF because of below>
   S <CR><LF>
   

   然后它关闭了连接。

我建议您需要彻底检查应用程序协议(protocol)。