I am trying to get into IoT and want to make an app send a string from an android phone to a Linux pc. The app does this by implementing an asynctask:
//From the java docs, slightly modified
private Void sendThroughSocket(String s, String host, int port) {
Log.d("E", "In send through socket");
final String hostName = host;//Host is the address of the receiver, can be IP or domain
int portNumber = port;
//Check if device is connected to internet
try {
Socket clientsocket = new Socket(hostName, portNumber); //one of 2-way point communication
Log.d("E", "Created Socket: ");
DataOutputStream DOS = new DataOutputStream(clientsocket.getOutputStream());
if (clientsocket.isConnected())
Log.d("E", "Socket connected");
DOS.writeUTF(s);
clientsocket.close();
} catch (UnknownHostException e) {
System.err.println("Don't know about host " + hostName);
new Runnable() {
public void run() {
Toast.makeText(context, "Don't know about host " + hostName, Toast.LENGTH_SHORT).show();
}
};
} catch (IOException e) {
System.err.println("Couldn't get I/O for the connection to " + hostName);
//Toast can not be run using asynctask since it acesses UI
new Runnable() {
public void run() {
Toast.makeText(context, "Couldn't get I/O for the connection to " + hostName + " , check the port", Toast.LENGTH_SHORT).show();
}
};
} catch (Exception e) {
Log.d("E", "#fares" + e.getClass().getName().toString());
}
return null;
}
On 3 occasions do I try to send the string, all triggered from my seekbar (I send the seek bar progress value as my string): public void onProgressChanged(SeekBar seekBar, int i, boolean b) public void onStartTrackingTouch(SeekBar seekBar) public void onStopTrackingTouch(SeekBar seekBar)
The implementation for all 3 is the same: public void onProgressChanged(SeekBar seekBar, int i, boolean b) {
progressvalue = i;
textView.setText("Brightness = " + progressvalue + " %");
if (((RecieverPort.equals("Please enter port Number")) || (RecieverIP.equals("Please enter receiver IP")))) {
//Make sure toast isn't persistent
if (IPPortToastcount++ == 0)
Toast.makeText(MainActivity.this, "Please set both IP and Port ", Toast.LENGTH_SHORT).show();
} else {
//Check if connected to internet
if (!isConnectedtoInternet(MainActivity.this)) {
if (ConnectivityToastCount++ < 1)
Toast.makeText(MainActivity.this, "You are not connected to the Internet", Toast.LENGTH_SHORT).show();
} else {
//Send text over wifi
SendText ST = new SendText(getApplicationContext());
ST.execute(String.valueOf(progressvalue), RecieverIP, RecieverPort);
ST.cancel(false);
}
}
}
Mainly
//Send text over wifi
SendText ST = new SendText(getApplicationContext());
ST.execute(String.valueOf(progressvalue), RecieverIP, RecieverPort);
ST.cancel(false);
The server side (my pc) is pretty simple:
int portNumber = 44339; // Choose unused port on router
//Open a socket
try {
//System.out.println("in try statement");
try (ServerSocket serverSocket1 = new ServerSocket(portNumber)) {
portNumber = serverSocket1.getLocalPort();
System.out.println("Created socket at port " + portNumber);
Socket clientSocket = serverSocket1.accept();
System.out.println("Accepted");
DataInputStream DIS = new DataInputStream(clientSocket.getInputStream()); //get input from socket
//System.out.println("Created reader");
String inputLine;
// System.out.println("About to read");
while (DIS.available() > 0) {
inputLine = DIS.readUTF();
System.out.println(inputLine);
}
}
} catch (Exception e) {
System.out.println("Exception caught when trying to listen on port "
+ portNumber + " or listening for a connection");
System.out.println(e.getClass().getSimpleName());
}
This kind of works, except it takes a very long time(seconds) before the server socket is accepted. It also only works in onprogresschanged , which leads me to believe that multiple attempts of
//Send text over wifi
SendText ST = new SendText(getApplicationContext());
ST.execute(String.valueOf(progressvalue), RecieverIP, RecieverPort);
ST.cancel(false);
are needed before one succeeds at creating the socket and connecting to the pc. How can I make sure that one tap, or one call of the function will be enough to send the string? Sorry for the long post but it's my first time asking :)
Edit: my new server code:
try {
//System.out.println("in try statement");
try ( ServerSocket serverSocket1 = new ServerSocket(portNumber))
{
portNumber = serverSocket1.getLocalPort();
System.out.println("Created socket at port " + portNumber);
while(true){
Socket clientSocket = serverSocket1.accept();
// System.out.println("Accepted");
DataInputStream DIS = new DataInputStream(clientSocket.getInputStream()); //get input from socket
//System.out.println("Created reader");
//String inputLine;
//System.out.println("About to read");
System.out.println(DIS.readUTF());
}
}
} catch (Exception e) {
System.out.println("Exception caught when trying to listen on port "
+ portNumber + " or listening for a connection");
System.out.println(e.getClass().getSimpleName());
}
Worth noting that even in the while true loop, the server will always display 4 numbers then stop.
Edit: here is an example log: 10-06 20:08:09.145 26372-26372/com.example.fares.ledslider D/E: #fares in test method value = 50 10-06 20:08:26.475 26372-26372/com.example.fares.ledslider D/E: #Fares in start tracking 10-06 20:08:26.722 26372-27004/com.example.fares.ledslider D/E: #fares Socket connected 10-06 20:08:26.810 26372-26764/com.example.fares.ledslider D/E: #fares Socket connected 10-06 20:08:27.241 26372-27003/com.example.fares.ledslider D/E: #fares Socket connected 10-06 20:08:27.304 26372-26372/com.example.fares.ledslider D/E: #fares in stop tracking
