java - 客户端程序响应http请求

Question

更新:感谢@MartinFrank 的想法，我将 http header 添加到结果中，并且它有效。

HTTP/1.1 200 OK
Content-Type: text/html
Content-Length: result.length()

<小时/>

我正在开发一个客户端程序来使用网络应用程序。 Web 服务器应用程序将向客户端发送“获取”请求。然后客户端程序将开始监听与秤设备连接的 COM 端口，并将结果重量以字符串形式返回到 Web 服务器应用程序。

我尝试使用 ARC 客户端发送请求来测试程序

http://localhost:8083/test

系统能够打印

Listening for connection on port 8083 ....
Just connected to /0:0:0:0:0:0:0:1:50346
GET /test HTTP/1.1
HOST: localhost:8083
result ??? 3 741g

但请求一直卡在请求阶段，没有响应结果，如下图:

ARC client

知道如何从客户端程序获得正确的响应吗？感谢您的帮助。

  static public void main(String[] args)
{

    ServerSocket server;
    try {
        server = new ServerSocket(8083);
    System.out.println("Listening for connection on port 8083 ...."); 
        while (true) {
            Socket clientSocket = server.accept();
            System.out.println("Just connected to " + clientSocket.getRemoteSocketAddress());
            InputStreamReader isr = new InputStreamReader(clientSocket.getInputStream());
            BufferedReader reader = new BufferedReader(isr);
            String line = reader.readLine();
            while (!line.isEmpty()) {
                System.out.println(line);
                line = reader.readLine();
            }
            String result = openConnection();.//listen to COM port and return weight result.
            var pw = new PrintWriter(clientSocket.getOutputStream(), true);
            System.out.print(" result ???  "+result);
            pw.println(result);
        }
    } catch (IOException e) {
        e.printStackTrace();
    } 

}

   public static String openConnection()
{
    if(comPort == null || !comPort.isOpen()) {
        comPort = SerialPort.getCommPorts()[0];
        comPort.setComPortParameters(2400,7,SerialPort.ONE_STOP_BIT,SerialPort.EVEN_PARITY);
        comPort.openPort();
        System.out.println("COM port open: " + comPort.getDescriptivePortName());
    }else {
        System.out.println("COM port already open: " + comPort.getDescriptivePortName());
    }
    while(fullWeight == null) {
        fullWeight = getWeight();
    }
    return fullWeight;

}

还尝试对结果进行硬编码并删除端口功能。

  static public void main(String[] args)
{
....
            //String result = openConnection();
            String result = "OK"; 
            var pw = new PrintWriter(clientSocket.getOutputStream(), true);
            pw.println(result);
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

Answer 1

我认为您需要刷新 PrintWriter 才能有效发送响应

pw.println(result);
pw.flush();