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The Android Client Can't Receive A Response From The Python Server

- 1 answer

The python server receives an image file from the android and sends the string "OK" in response. The source code of the python server is as follows:

serverSocket = socket(AF_INET, SOCK_STREAM)

serverSocket.bind(ADDR)
print('bind')

serverSocket.listen(CLIENT_NUM)
print('listen')

while True:
print('waiting...')
try:
    connectionSocket, addr_info = serverSocket.accept()
    print('accept')
    print('--client information--')
    print(connectionSocket)

    img = open("./img.jpg", 'wb')
    while True:
        img_data = connectionSocket.recv(BUFSIZE)
        data = img_data
        if img_data:
            while img_data:
                print("receiving Img...")
                img_data = connectionSocket.recv(BUFSIZE)
                data += img_data
            else:
                break
    img_file = open("img.jpg", "wb")
    print("finish img recv")
    img_file.write(data)
    img_file.close()

    connectionSocket.send("OK".encode())
    connectionSocket.close()
    print('connection closed')

except KeyboardInterrupt:
    sys.exit(0)

The android client sends an image file to the python server and it receive the string "OK" from python server. The source code of python server is as follows:

 public void run() {
    try {
        InetAddress serverAddr = InetAddress.getByName(serverIp);
        socket = new Socket(serverAddr, serverPort);
        try {
            dataOutput = new DataOutputStream(socket.getOutputStream());
            dataInput = new DataInputStream(new FileInputStream(img));

            byte[] buf = new byte[BUF_SIZE];
            int dataLen;
            while ((dataLen = dataInput.read(buf)) != -1) {
                dataOutput.write(buf, 0, dataLen);
                dataOutput.flush();
            }
            BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            Log.d("Socket", reader.readLine());
        } catch (Exception e) {
            StringWriter sw = new StringWriter();
            e.printStackTrace(new PrintWriter(sw));
            String exceptionAsString = sw.toString();
            Log.e("StackTrace", exceptionAsString);
        } finally {
            try {
                if (dataInput != null)
                    dataInput.close();
                if (dataOutput != null)
                    dataOutput.close();
                if (socket != null)
                    socket.close();
            } catch (IOException e) {
                StringWriter sw = new StringWriter();
                e.printStackTrace(new PrintWriter(sw));
                String exceptionAsString = sw.toString();
                Log.e("StackTrace", exceptionAsString);
            }
        }
    } catch (IOException e) {
        StringWriter sw = new StringWriter();
        e.printStackTrace(new PrintWriter(sw));
        String exceptionAsString = sw.toString();
        Log.e("StackTrace", exceptionAsString);
    }

}

The server cannot

If I delete the two lines below, the server receives the file normally. But if I insert the two lines below, the server doesn't receive the file.

BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
Log.d("Socket", reader.readLine());

How can the android client send an image file to the python server and get a response?

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Answer

I solved this problem. I thought the cause of this problem must have been on the server side, so I modified the code of server and it worked!

img = open("./img.jpg", 'wb')
img_data = connectionSocket.recv(BUFSIZE)
data = img_data
firstPacketLen = len(img_data)
print("receiving Img...")
while len(img_data) > 0:
    img_data = connectionSocket.recv(BUFSIZE)
    data += img_data
    if len(img_data) < firstPacketLen:
        break
print("finish img recv")
img.write(data)
img.close()

connectionSocket.send("OK\r\n".encode())
connectionSocket.shutdown(SHUT_RDWR)
connectionSocket.close()
print('connection closed')
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source: stackoverflow.com
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