Sockets 从 Java 到 Python 并再次返回

Question

Is it possible to communicate with a Raspberry Pi from an Android phone through an app? I've tried and succeded in sending information form the Android App to the RaspberryPi. But when I try to connect to the phone from the RPi by calling phoneServer.connect(addr) , python just times out. So is it possible to send a command from the Python Socket to the Java Socket?

Initialy I had one socket in the python script and I just used tcpCliSock.sendto(data.encode(),addr) to try and send the command to the java socket, but that resulted in a broken pipe errer (32), so I thought I might be able to fix it by creating a new socket, but it hasn't fixed the issue.

I've currently tried setting up sockets in Python and in Java. The ones in Python (on RPi) looks something like this:

HOST = ''
PORT = 21567
BUFSIZE = 1024
ADDR = (HOST,PORT)

tcpSerSock = socket(AF_INET, SOCK_STREAM)
tcpSerSock.bind(ADDR)
tcpSerSock.listen(5)

PORTSEND = 7801
while True:
    print('Waiting for connection')
    tcpCliSock,addr = tcpSerSock.accept()
    data = ''
    print('...connected from :', addr)
    try:
        while True:
            d = tcpCliSock.recv(BUFSIZE)
            data = data + d.decode("utf-8")
            print(data)    
            if data == 'XButton':
                print('XButton Pressed')
                lst = list(addr)
                lst[1] = PORTSEND
                addr = tuple(lst)
                phoneServer = socket(AF_INET, SOCK_STREAM)
                phoneServer.connect(addr)
                phoneServer.send(data.encode())
                phoneServer.close()
                break
            else:
                if not d:
                    break
    except KeyboardInterrupt:
        print('keyboard pressed')

tcpSerSock.close()

And the ones in Java (on the Android) looks something like this:

public class MainActivity extends AppCompatActivity  {
    EditText iPField;
    Button xButton;
    public static String wifiModuleIp = "";
    public static int wifiModulePort = 0;
    public static String CMD = "0";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Thread myThread = new Thread(new MyServerThread());
        myThread.start();

        iPField = (EditText) findViewById(R.id.IPEditField);
        xButton = (Button) findViewById(R.id.XButton);

        xButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                getIPandPort();
                CMD = "XButton";
                Socket_AsyncTask cmd_verify = new Socket_AsyncTask();
                cmd_verify.execute();
            }
        });

    public void getIPandPort()
    {
        String iPandPort = iPField.getText().toString();
        Log.d("MYTEST","IP String: "+ iPandPort);
        String temp[]= iPandPort.split(":");
        wifiModuleIp = temp[0];
        wifiModulePort = Integer.valueOf(temp[1]);
        Log.d("MY TEST","IP:" +wifiModuleIp);
        Log.d("MY TEST","PORT:"+wifiModulePort);
    }
    public class Socket_AsyncTask extends AsyncTask<Void,Void,Void>
    {
        Socket socket;

        @Override
        protected Void doInBackground(Void... params){
            try{
                InetAddress inetAddress = InetAddress.getByName(MainActivity.wifiModuleIp);
                socket = new java.net.Socket(inetAddress,MainActivity.wifiModulePort);
                DataOutputStream dataOutputStream = new DataOutputStream(socket.getOutputStream());
                dataOutputStream.writeBytes(CMD);
                dataOutputStream.close();
                socket.close();
            }catch (UnknownHostException e){e.printStackTrace();}catch (IOException e){e.printStackTrace();}
            return null;
        }
    }

    class MyServerThread implements Runnable
    {
        Socket s;
        ServerSocket ss;
        InputStreamReader isr;
        BufferedReader bufferedReader;
        String message;
        Handler h = new Handler();

        @Override
        public void run() {
            try
            {
                ss = new ServerSocket(7801);
                while(true)
                {
                    s = ss.accept();
                    isr = new InputStreamReader(s.getInputStream());
                    bufferedReader = new BufferedReader(isr);
                    message = bufferedReader.readLine();

                    h.post(new Runnable() {
                        @Override
                        public void run() {
                            Toast.makeText(getApplicationContext(),message,Toast.LENGTH_SHORT).show();
                        }
                    });

                }

            }catch(IOException e)
            {
                e.printStackTrace();
            }
        }
    }
}

Answer 1

I use for such tasks ready libraries for html retrieve.

For example, on Android exists org.apache.http.client (now they recommend newer library, but old still works well). And Python also have http client in standard library https://docs.python.org/3/library/http.client.html

It is convenient and save lot of time, REusing some ready code for general tasks.