Android - Reading http request

Question

I'm doing a project with Arduino and Android application. Here's how it goes, send from the application request "a=11&b=22&d=33" (http://192.168.0.17/?a=11&b=22&d=33), arduino read and return "Data_received" and I use it to do something (down is part of code from app). And everything is going well. But I do not know how to do reversed now, I know how to send the request from arduino to server, but I don't know how to receive in android app to get a = 11, b = 22, c = 33. Android studio code to receive:

 @Override
    protected void onPostExecute(String s) {

        if (serverResponse.toString().equals("Data_received")  ){

           Toast.makeText(Test.this, "Data is ok...", Toast.LENGTH_SHORT).show();

        }
        else{

            Toast.makeText(Test.this, "Connection is not ok", Toast.LENGTH_SHORT).show();

        }

    }

Arduino code which receives request in arduino:

boolean currentLineIsBlank = true;
boolean currentLineIsGet = true;
int tCount = 0;
char tBuf[64];
int a;
int b;
int d;
char *pch;
while (client.connected()) {
  while (client.available()) {

    char c = client.read();
    if (currentLineIsGet && tCount < 63)
    {
      tBuf[tCount] = c;
      tCount++;
      tBuf[tCount] = 0;
    }


    if (c == '\n' && currentLineIsBlank) {
      while (client.available()) client.read();

      Serial.print (tBuf);
      pch = strtok(tBuf, "?");

      while (pch != NULL) {

        //  http://192.168.0.17/?a=11&b=22&d=33
        if (strncmp(pch, "a=", 2) == 0)  {
          a = atoi(pch + 2);
          Serial.print("a=");
          Serial.println(a, DEC);
        }
        if (strncmp(pch, "b=", 2) == 0)  {
          b = atoi(pch + 2);
          Serial.print("b=");
          Serial.println(b, DEC);
        }
        if (strncmp(pch, "d=", 2) == 0) {
          d = atoi(pch + 2);
          Serial.print("d=");
          Serial.println(d, DEC);
        }
        pch = strtok(NULL, "& ");

      }  //  while (pch != NULL)

      client.stop();
    }

   }
}

All code:

public class Test extends AppCompatActivity {

     public EditText text__T1mod;
        public EditText text__T2mod; 
        public EditText text__T3mod; 



private TextView Text_Arduino;

private Button SendRequest ;

public int a;
public int b;
 public int c;

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



    SendRequest  = (Button) findViewById(R.id.btn_SendRequest );



    text__T1mod = (EditText) findViewById(R.id.TextEdit_T1);
    text__T2mod = (EditText) findViewById(R.id.TextEdit_T2);
    text__T3mod = (EditText) findViewById(R.id.TextEdit_T3);


    Text_Arduino = (TextView) findViewById(R.id.textView_Arduino);


}  //  protected void onCreate  END




public void clik_SendRequest (View view) {

    String RequestString = "";

    if (IpAddres.getText().toString().equals(""))
        Toast.makeText(this, "Enter IP", Toast.LENGTH_SHORT).show();

    else {

        if (view == SendRequest )

         //  http://192.168.1.14/?a=11&b=22&d=33
        RequestString = "a=" + text__T1mod.getText().toString() + "&"
                     +  "b=" + text__T2mod.getText().toString() + "&"
                     +  "d=" + text__T3mod.getText().toString() ;

                              // 192.168.1.14                         // 80
        String serverAdress = IpAddres.getText().toString() + ":" + Port.getText().toString() + "?";
        HttpRequestTask requestTask = new HttpRequestTask(serverAdress);
        requestTask.execute(RequestString);

    }  //  else END

} // clik_SendRequest END


private class HttpRequestTask extends AsyncTask<String, Void, String> {

    private String serverAdress;
    private String serverResponse = "";
    private AlertDialog dialog;

    public HttpRequestTask(String serverAdress) {
        this.serverAdress = serverAdress;

        dialog = new AlertDialog.Builder(context)
                .setTitle("HTTP zahtev za Ip adresu: ")
                .setCancelable(true)
                .create();


    }

    @Override
    protected String doInBackground(String... params) {

        String val = params[0];

        final String url = "http://" + serverAdress  + val;



        try {
            HttpClient client = new DefaultHttpClient();
            HttpGet getRequest = new HttpGet();
            getRequest.setURI(new URI(url));
            HttpResponse response = client.execute(getRequest);

            InputStream inputStream = null;
            inputStream = response.getEntity().getContent();
            BufferedReader bufferedReader =
                    new BufferedReader(new InputStreamReader(inputStream));

            serverResponse = bufferedReader.readLine();
            inputStream.close();


        } catch (URISyntaxException e) {

            Log.e("", "parse error2: " + e.toString());
            e.printStackTrace();
            serverResponse = e.getMessage();
        } 

        return serverResponse;
    }




    @Override
    protected void onPostExecute(String s) {

        /*
                ----- HERE I NEED IF SOMETHING LIKE arrives ----
         if (serverResponse.toString().equals("?a=11&b=22&d=33")  ){

           Toast.makeText(Test.this, "a=" a + "b=" b + "c=" c , Toast.LENGTH_SHORT).show();
        }
        else{
            Toast.makeText(Test.this, "Connection is not ok", Toast.LENGTH_SHORT).show();
        }
        */

    }


    @Override
    protected void onPreExecute() {
        Text_Arduino.setText("pleas wait...");
    }


} //  private class HttpRequestTask

} // public class Test END

Answer 1

You have 2 options:

• Poll the server: write a function on the server that returns the results you need. Then setup a timer in android that calls this function every few seconds

• Push messages from the server: use a push service to send your results to the android app. ex: https://firebase.google.com/docs/cloud-messaging/

To parse your server response string:

String serverResponse = "?a=11&b=22&d=33";
String[] args = serverResponse.substring(1).split("&");
String a = args[0].split("=")[1];
String b = args[1].split("=")[1];
String c = args[2].split("=")[1];