I try to create a Simple TCP Server on Android phone and waiting for client.
I only want to implement the connection between TCPServer and Client , it doesn't need to transmit any data.
I have the another application for client , It use to connect to this TCPServer.
The code of TCPServerthread is like the following.
private class TCPServerThread implements Runnable
{
#Override
public void run() {
// TODO Auto-generated method stub
try {
ServerSocket serverSocket = new ServerSocket(PORT);
//while loop
while (true) {
Log.i(TAG, "TCPServerThread...while loop");
try {
Socket socket = serverSocket.accept();
Log.i(TAG, "TCPServerThread...socket.getInetAddress() = " + socket.getInetAddress());
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
Log.i(TAG, "First IOException");
}
}
//while loop end
} catch (Exception e) {
// TODO: handle exception
//e.printStackTrace();
Log.i(TAG, "Second IOException");
}
}
}
But it seems stop at Socket socket = serverSocket.accept(); and doesn't show the log of TCPServerThread...socket.getInetAddress() = when the client try to connect to this Server.
DO I missing something for TCPServer ?
Is it mean the client doesn't connect to the Server when the code stop at Socket socket = serverSocket.accept(); ??
----------------------------EDIT----------------------------------------
Update the process.
The Server(Android Phone) open the WiFi-Hot-Spot, it also open the TCP-Server like the above code.
After Client connect to WiFi-Hot-Spot , the Client and the Server are in the same network.
The Client will get a IP address of gateway, and the Client try to connect to this IP address of gateway by TCP.
So the connection port and Server address seems correct for Client.
Your code is correct, but it seems that no one is connecting to your TCPserver.
To avoid this blocking situation on
Socket socket = serverSocket.accept();
you have to set the timeout option for your socket when you declare it
serverSocket.setSoTimeout(mTime);
;)
Related
I am using Tcp Sockets For Communication Between CLR C++ (Server) to Android(Client) While using .Net For GUI.
While the data is communicated and received. Using a Background Worker in C++ Application
if(backgroundworker1->CancellationPending)
{
listenerSocket->Close(); // Listener Socket is Closed
netStream->Close();
serverSocket->Close();
serverSocket->Shutdown(SocketShutdown::Both);
e->Cancel;
break;
}
While in Android i am using Async Class for Execution and receiving text from socket to a Handler. While in Doinbackground Function i am using this code.
try
{
socket = new Socket(dstAddress, dstPort);
BufferedReader inputStream = new BufferedReader(new InputStreamReader(socket.getInputStream()));
do
{
try
{
if (!inputStream.ready())
{
if (message != null)
{
MainActivity.handler.obtainMessage(0, 0, -1,"Server: " + message).sendToTarget();
message = "";
}
}
int num = inputStream.read();
message += Character.toString((char) num);
Log.e(message,message);
}
catch (Exception classNot)
{
Log.e("Client TASK","classnot exception");
}
}
while (!message.equals("bye"));
inputStream.close();
socket.close();
}
I don't understand While am sending the Bye Message from the server and (Backgroundworker1->CancellationPending)
All server sockets are closed and Mobile Sockets are closed why is the UI Not Responding? Please Help..
The Problem was in Client in doinbackground Which calls the while loop again hence causing an exception because no data was received in the sockets and causing an exception. Finally added some sleep to the client that after some time the client query the server while if there is no message from the server the client shutdowns and shifted to postexecution function.
I am doing socket programming. I took reference from below link:
http://examples.javacodegeeks.com/android/core/socket-core/android-socket-example/
Below is detail about my issue. I have created Android lib for this ServerThread (my project requirement), and this is used in test app.
Now test app connect to this through lib and do the process. First time it works perfectly fine, but if I closed and reopen it crashed with exception:
"EADDRINUSE (Address already in use)"
Also tried serverSocket.setReuseAddress(true) this but no luck.
My code:
public void run() {
Socket socket = null;
try {
serverSocket = new ServerSocket(SERVER_PORT);
serverSocket.setReuseAddress(true);
} catch (IOException e) {
Log.e(TAG, "exception1= " + e.getMessage());
}
while (!Thread.currentThread().isInterrupted()) {
try {
socket = serverSocket.accept();
Log.d(TAG, "server Connected.......!!!!");
communicationThread = new CommunicationThread(
socket);
commThread = new Thread(communicationThread);
commThread.start();
} catch (IOException e) {
Log.e(TAG, "exception 2=" + e.getMessage());
}
}
}
If I call serverSocket.close() I am getting exception 2 as server socket close. Communication thread is same as given in previous link.
You have to call setReuseAddress(true) before the socket is bound to the port. You are calling it after, because you are passing the port to the constructor, which will bind the socket immediately.
Try this instead:
serverSocket = new ServerSocket(); // <-- create an unbound socket first
serverSocket.setReuseAddress(true);
serverSocket.bind(new InetSocketAddress(SERVER_PORT)); // <-- now bind it
TCP (and probably some other) sockets can't reuse the same port for a period after closing. This is to prevent confusion if there's data on the network from an existing connection. You can override this behavior, but the default is to wait for a period of time before allowing reuse of the port.
The call to fix this is setReuseAddress(true) on the server socket. But I'm not sure if it needs to be called on the first socket or the second, or both.
Edit:
Here's a blog post describing the TCP socket TIME_WAIT state and why it exists: http://www.serverframework.com/asynchronousevents/2011/01/time-wait-and-its-design-implications-for-protocols-and-scalable-servers.html
While other answers pointed out the importance of setReuseAddress(true), another problem that could arise is to construct the ServerSocket twice and call bind with the same parameters. For example if you call twice the code run() of the question, serverSocket will be assigned to a new instance of the ServerSocket class, but the old one is still living until garbage collected. Now constructing with the port value as parameter equals to bind the ServerSocket object, and you are going to end up with two ServerSocket bound to the same address, which is forbidden hence the exception. So build your serverSocket with your chosen port only once!
Try to create the instance of SocketServer outside of the run() method.
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState)
try {
// create a new instance of an unbound socket first
serverSocket = new ServerSocket();
} catch (IOException e) {
e.printStackTrace();
}
}
I'm trying to establish a bluetooth communication between an android phone/tablet (4.0.3), and a bluetooth device, which is an earring reader (Destron Fearring DTR3E, in case you want to know, which I don't suppose you do).
I paired the phone with the reader (the reader has the pairing passcode on a tag) from the bluetooth settings, bluetooth is on of course, and now I'm trying to listen to reads from the device, by means of BluetoothServerSocket. The problem is that the accept call never returns, so obviously I am doing something wrong. The communication is done using RFCOMM.
Code:
private class AcceptThread extends Thread {
private final BluetoothServerSocket mmServerSocket;
public AcceptThread() {
// Use a temporary object that is later assigned to mmServerSocket,
// because mmServerSocket is final
BluetoothServerSocket tmp = null;
try {
// MY_UUID is the app's UUID string, also used by the client code
String uuid = "00001101-0000-1000-8000-00805F9B34FB";
tmp = bluetoothAdapter.listenUsingInsecureRfcommWithServiceRecord("pdfParserServer", UUID.fromString(uuid));
} catch (Exception e) {
e.printStackTrace();
}
mmServerSocket = tmp;
}
public void run() {
BluetoothSocket socket = null;
// Keep listening until exception occurs or a socket is returned
while (true) {
try {
socket = mmServerSocket.accept();
} catch (IOException e) {
break;
}
// If a connection was accepted
if (socket != null) {
// Do work to manage the connection (in a separate thread)
try {
mmServerSocket.close();
} catch (IOException e) {
e.printStackTrace();
}
break;
}
}
}
/** Will cancel the listening socket, and cause the thread to finish */
public void cancel() {
try {
mmServerSocket.close();
} catch (IOException e) { }
}
}
Is there something I am missing?
Thank you!
The only reason that could cause the code never to come back from accept is that, the device "Destron Fearring DTR3E" you are trying to connect to, has actually a bluetoothserver socket and not a bluetooth client, hence, the device might be waiting for you to actually connect to it, in stead of you creating a bluetoothserver socket and waiting for it to connect to your android device, you should read the specs on the device and make sure that actually is you the one that has to open a connection on "Destron Fearring DTR3E" socket...
Hope this helps...
Regards!
I've been trying to implement a simple socket communication between two Android emulators but just can't seem to get it.
My server:
public void run() {
if (SERVERIP != null) {
try {
serverStatus.setText("My IP: " + SERVERIP);
serverSocket = new ServerSocket(6798);
serverStatus.setText("ServerSocket Created");
}
catch(Exception e) {
e.printStackTrace();
}
try {
while (true) {
serverStatus.setText("waiting for client");
Socket client = serverSocket.accept();
serverStatus.setText("Connected.");
BufferedReader in = new BufferedReader(new InputStreamReader(client.getInputStream()));
String line = in.readLine();
serverStatus.setText(line);
in.close();
client.close();
}
}
catch(Exception e) {
e.printStackTrace();
}
}
else
serverStatus.setText("Couldn't detect internet connection.");
}
My Client:
try {
InetAddress ina = InetAddress.getByName("10.0.2.2");
socket = new Socket(ina, 6789);
}
catch (Exception e) {
e.printStackTrace();
}
try {
PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())), true);
out.println("Hey Server!");
dispText.setText("sent");
}
catch (Exception e) {
e.printStackTrace();
}
The Client side goes on to display the message "sent" however the Server does not move beyond "waiting for client" (stuck on the blocking accept()).
I've used telnet on my Windows machine to redirect port 6789 to 6798 on the server emulator's console. I've also tried turning off my firewall and the other suggestions posted on the similar questions asked here. Please help as just can't seem to get it and feel like I'm making a very stupid mistake.
Also, can anyone please tell me how it is possible for the Client to move beyond the Socket creation code line if the Server is still stuck on accept(). Or, does it not matter to the client that the Server isn't responding as long as it is listening on the port??
Android emulators are placed behind a virtual firewall/router by design, and cannot see each other, even when they are on the same network. The "Using Network Redirection", as well as "Interconnecting Emulator Instances" part of Google's doc on the emulator explains how to communicate with an emulator instance.
As for your last question. Use the empty constructor for socket, and then use the connect call with a specified timeout.
I have a Bluetooth server listening for incoming connection, on the Laptop.
Android is a client and wants to connect to PC.
What's wrong?
I can connect first time and send data to PC. When I turn off the Android Activity and start it again, connect function passes, but PC does not register new connection. When I try sending the data, android system logs following:
05-16 13:11:17.091: ERROR/BluetoothEventLoop.cpp(102): event_filter: Received signal org.bluez.Device:PropertyChanged from /org/bluez/30064/hci0/dev_50_63_13_CB_52_96
What works?
If I change server's UUID, on the server and on the client, it will work again first time I try connection. Consequent tries do not work.
Server code:
/** Waiting for connection from devices */
private void waitForConnection() {
// retrieve the local Bluetooth device object
LocalDevice local = null;
StreamConnectionNotifier notifier;
StreamConnection connection = null;
// setup the server to listen for connection
try {
local = LocalDevice.getLocalDevice();
local.setDiscoverable(DiscoveryAgent.GIAC);
UUID uuid = new UUID("af29e59088cc11e1b0c40800200c9a56", false);
System.out.println(uuid.toString());
String url = "btspp://localhost:" + uuid.toString() + ";name=ThinBTClient";
notifier = (StreamConnectionNotifier)Connector.open(url);
} catch (Exception e) {
e.printStackTrace();
return;
}
// waiting for connection
while(true) {
try {
System.out.println("Wait Thread: Waiting for connection...");
connection = notifier.acceptAndOpen();
System.out.println("Got connection");
Thread processThread = new Thread(new ProcessConnectionThread(connection));
processThread.start();
} catch (Exception e) {
e.printStackTrace();
return;
}
}
}
Client code:
BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(address);
UUID SPP_UUID = UUID.fromString("af29e590-88cc-11e1-b0c4-0800200c9a56");
try {
btSocket = device.createRfcommSocketToServiceRecord(SPP_UUID);
mBluetoothAdapter.cancelDiscovery();
btSocket.connect();
outStream = btSocket.getOutputStream();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Any ideas?
Update:
I tested the same code on another laptop, Toshiba/Win7 and code works without a problem. So I suspect this is something with drivers. I will try updating.