I have c++ socket server and android client. Server constantly sends data to the client after a time interval. The question is how to implement this getting data on android client
socket = new Socket("xxx.xxx.xxx.x", xxxx); // I connect
.... socket.getInputStream(); // Get first input stream
How to make it continuously receiving data? I tried something like this while(true) { ..socket.getInputStream(); Thread.sleep(...); } It didn't help
Note that you have to open the input stream only once. Then, if you perform a read() operation on the input stream it will block (of course if you use a blocking read (blocking vs non-blocking read) ).
You can find information about java socket programming here: link
You can find lost of examples for socket programming on Android platform here: link
For example:
BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
String line = "";
while (true) {
line = br.readLine(); // at this line, execution will stop until data is received
System.out.println("The read line is: " + line);
}
br.close();
You can use this Webstart Application and create a local server by providing your ip address and the Port and can use the same ip address and port in the code below which acts as a client...! You can both send and receive msgs. And yes provide INTERNET Permission in AndroidManifest.
MainActivity.java
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.SocketAddress;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Environment;
import android.util.Base64;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.TextView;
public class MainActivity extends Activity {
Button btnStart, btnSend, disconnect;
TextView textStatus;
EditText message, ipAddress, port;
ImageView image;
NetworkTask networktask;
String ip, prt;
Socket nsocket;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
btnStart = (Button)findViewById(R.id.btnStart);
disconnect = (Button)findViewById(R.id.bDisconnect);
btnSend = (Button)findViewById(R.id.btnSend);
textStatus = (TextView)findViewById(R.id.textStatus);
image = (ImageView)findViewById(R.id.ivBit);
message = (EditText) findViewById(R.id.message);
ipAddress = (EditText)findViewById(R.id.ipAddress);
port = (EditText)findViewById(R.id.port);
btnStart.setOnClickListener(btnStartListener);
btnSend.setOnClickListener(btnSendListener);
disconnect.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
try {
nsocket.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
});
// networktask = new NetworkTask(ip, prt); //Create initial instance so SendDataToNetwork doesn't throw an error.
}
private OnClickListener btnStartListener = new OnClickListener() {
public void onClick(View v){
disconnect.setVisibility(View.VISIBLE);
btnStart.setVisibility(View.GONE);
ipAddress.setEnabled(false);
port.setEnabled(false);
ip = ipAddress.getText().toString();
prt = port.getText().toString();
System.out.println("IPADDRESS :::::::" + ip);
System.out.println("PORT :::::::" + prt);
networktask = new NetworkTask(ip, prt); //New instance of NetworkTask
networktask.execute();
}
};
private OnClickListener btnSendListener = new OnClickListener() {
public void onClick(View v){
textStatus.setText("Sending Message to AsyncTask.");
networktask.SendDataToNetwork(message.getText().toString() + "\n");
}
};
public class NetworkTask extends AsyncTask<Void, byte[], Boolean> {
//Network Socket
InputStream nis; //Network Input Stream
OutputStream nos; //Network Output Stream
String data = ""; //Data Received
String ip, prt;
public NetworkTask(String ip, String prt) {
// TODO Auto-generated constructor stub
this.ip = ip;
this.prt = prt;
}
@Override
protected void onPreExecute() {
Log.i("AsyncTask", "onPreExecute");
}
@Override
protected Boolean doInBackground(Void... params) { //This runs on a different thread
boolean result = false;
try {
Log.i("AsyncTask", "doInBackground: Creating socket");
SocketAddress sockaddr = new InetSocketAddress(ip, Integer.parseInt(prt)); //192.168.2.102 118.139.161.101
nsocket = new Socket();
nsocket.connect(sockaddr, 500); //10 second connection timeout
if (nsocket.isConnected()) {
nis = nsocket.getInputStream();
nos = nsocket.getOutputStream();
Log.i("AsyncTask", "doInBackground: Socket created, streams assigned");
Log.i("AsyncTask", "doInBackground: Waiting for inital data...");
byte[] buffer = new byte[4096];
int read = nis.read(buffer, 0, 4096); //This is blocking
while(read != -1){
byte[] tempdata = new byte[read];
System.arraycopy(buffer, 0, tempdata, 0, read);
publishProgress(tempdata);
Log.i("AsyncTask", "doInBackground: Got some data");
read = nis.read(buffer, 0, 4096); //This is blocking
}
}
} catch (IOException e) {
e.printStackTrace();
Log.i("AsyncTask", "doInBackground: IOException");
result = true;
} catch (Exception e) {
e.printStackTrace();
Log.i("AsyncTask", "doInBackground: Exception");
result = true;
} finally {
try {
nis.close();
nos.close();
nsocket.close();
} catch (IOException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
Log.i("AsyncTask", "doInBackground: Finished");
}
return result;
}
public void SendDataToNetwork(String cmd) { //You run this from the main thread.
try {
if (nsocket.isConnected()) {
Log.i("AsyncTask", "SendDataToNetwork: Writing received message to socket");
nos.write(cmd.getBytes());
} else {
Log.i("AsyncTask", "SendDataToNetwork: Cannot send message. Socket is closed");
}
} catch (Exception e) {
Log.i("AsyncTask", "SendDataToNetwork: Message send failed. Caught an exception");
}
}
@Override
protected void onProgressUpdate(byte[]... values) {
if (values.length > 0) {
Log.i("AsyncTask", "onProgressUpdate: " + values[0].length + " bytes received.");
data += new String(values[0]);
textStatus.setText(data);
System.out.println("DATA RECEIVED..........." + (data));
}
}
@Override
protected void onCancelled() {
Log.i("AsyncTask", "Cancelled.");
disconnect.setVisibility(View.VISIBLE);
btnStart.setVisibility(View.GONE);
ipAddress.setEnabled(true);
port.setEnabled(true);
}
@Override
protected void onPostExecute(Boolean result) {
if (result) {
Log.i("AsyncTask", "onPostExecute: Completed with an Error.");
textStatus.setText("There was a connection error.");
} else {
Log.i("AsyncTask", "onPostExecute: Completed.");
}
disconnect.setVisibility(View.GONE);
btnStart.setVisibility(View.VISIBLE);
ipAddress.setEnabled(true);
port.setEnabled(true);
}
}
@Override
protected void onDestroy() {
super.onDestroy();
networktask.cancel(true); //In case the task is currently running
}
}
main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<EditText
android:id="@+id/ipAddress"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:digits="0123456789."
android:inputType="number" />
<EditText
android:id="@+id/port"
android:layout_width="100dp"
android:layout_height="wrap_content"
android:digits="0123456789."
android:inputType="number" />
<Button
android:id="@+id/bDisconnect"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:visibility="gone"
android:text="Disconnect" />
<Button
android:id="@+id/btnStart"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Start AsyncTask" >
</Button>
<EditText
android:id="@+id/message"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:ems="10"
android:inputType="textMultiLine" >
</EditText>
<Button
android:id="@+id/btnSend"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Send Message" >
</Button>
<ScrollView
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<TextView
android:id="@+id/textStatus"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Status Goes Here"
android:textSize="24sp" />
<ImageView
android:id="@+id/ivBit"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
</ScrollView>
</LinearLayout>
