i want to program a server/client app in android.
i have one server class on my pc and client on my android phone.
all permissions are ok.
Here is client:
try {
mysocket = new Socket("My PC IP Address", 4444);
} catch (UnknownHostException e) {...
} catch (IOException e) {...
}
here is server:
try {
myServerSocket = new ServerSocket(4444);
} catch (IOException e) {...
}
Socket clientSocket = null;
try {
clientSocket = serverSocket.accept();
System.out.println("Connection Established.");
} catch (IOException e) {
}
I uses "Connectify" program on my pc to have an (virtual)access point such that my phone connect to that.
But when I try to connect to server in my android app, it hangs and then throws Timed-out exception.
This code doesn't look bad.
Are you certain Connectify is working well?
You shoud try running both the server and the client you have built on your PC, using two different processes (as an example the server as a standalone and the client in the Android Emulator).
If it works properly from localhost to localhost:4444, the the connection is the cause of the problem, not your code. And otherwise, you will easily find the bug in your code.
Related
I am creating some testing app, and I need to connect several devices via Wi-Fi direct. On Android 8 the only way to do it is to create LocalOnlyHotspot. I have done it successfully, devices are connecting. However I need to transfer some strings between devices. For those reason I have made in separate threads
-> on server side
try{
int port = 9802;
ServerSocket serverSocket = new ServerSocket(port);
running = true;
while (running){
Socket socket = serverSocket.accept();
}
} catch (IOException e) { e.printStackTrace(); }
-> on client side
Socket socket = null;
try{
socket = new Socket(address, port);
} catch (IOException e) { e.printStackTrace(); }
I am always getting an exception on client's side
failed to connect to /192.168.43.1 (port 9802) from /:: (port 33044): connect failed: ECONNABORTED (Software caused connection abort)
As I have googled the reason is that the network has no internet connection.
How can I solve this problem? Is any other way to pass strings between 2 devices on Android 8 using Wi-Fi direct?
Thanks in advance.
I am trying to get some experience with Java network programming. So I made a simple text based game. This is how it looks on serverside:
try {
socket = new ServerSocket(PORT);
while(true) {
new ConnectedPlayer(socket.accept()).start();
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
And this is the client:
System.setProperty("java.net.preferIPv6Addresses","true");
try {
InetAddress ad = InetAddress.getByName("2a02:8070:b84:6b00:a1d1:30d7:346b:7c14");
socket = new Socket(ad, 9001);
output = socket.getOutputStream();
out = new PrintWriter(output);
in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
The address above is the Ipv6 address of the machine running
the server, I got this one by a website which detects my IP addresses,
it is different from what I get when I use ipconfig though, tried it with both.
When I tested both on the same machine with localhost, it worked.
However, now I wanted to try it on two different machines, one in a different network. Problem is, my internet provider apparently restricts me to something called "dual stack lite" which means my Server could only be reached over Ipv6 if I understand it correctly. But then, no port forwarding is needed there. When I test it now, it won't connect and gives a timeout after some time. I disabled firewalls on both machines.
When running a ServerSocket on a machine A with ip 145.74.217.109
And then trying to connect to machine A using machine B with ip 145.74.219.103 I am unable to connect.
But when using machine C with ip 145.74.217.180 it works.
Iam not sure if this is solvable in code or its just network settings. If It is network issues is there another way to go around this problem or would I need to go away from sockets to ...?
Machine A:
public void run() {
try {
sock = new ServerSocket(Constants.PORT);
for (;;) {
Socket newsock = sock.accept();
System.out.println("Accepting new player: ");
new PaintballPlayer(newsock);
}
} catch (Exception e) {
System.out.println("IO error " + e);
}
System.out.println("End!");
try {
sock.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
Machine B, C :
socket = new Socket(ip, Constants.PORT);
if you look at the IP us server has IP 145.74.217.109 IP with 145.74.217.180 are able to connect while 145.74.219.103 is not being able to connect it means subnet 145.74.219.X has no access to 145.74.217.X that is why it is not being able to connect. It is network setting ask you network administrator for that. Make your both machine have same subnet mask
I have an app in android in which I created an android client and a Java sever.
But I'm confronting the following issue: my client (the android part) connects to the local machine on port 6000 using the android loopback address.
My server (in Java) listens on local machine at the port 6000 - but what is the IP I have to use to get the socket that accepts the clients?
InetSocketAddress serverAddr = new InetSocketAddress(SERVERIP,serverPort);
serverSocket = new ServerSocket();
serverSocket.bind(serverAddr);
So what is the SERVERIP I have to use?
UPDATE:My client runns on an emulator!!!!!
EDIT:
public class ClientThread implements Runnable {
Object syncToken;
public ClientThread(Object syncToken) {
this.syncToken = syncToken;
}
public void run() {
try {
InetAddress serverAddr = InetAddress.getByName(serverIpAddress);
socket = new Socket(serverAddr, 50458);
} catch (UnknownHostException e) {
System.err.println("Don't know about host");
} catch (IOException e) {
System.err
.println("Couldn't get I/O for the connection to host");
}
try {
out = new PrintStream(socket.getOutputStream());
} catch (IOException e) {
System.out.println(e);
}
while (true) {
synchronized (syncToken) {
try {
syncToken.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}
And here is: private String serverIpAddress = "10.0.2.2";!!!!!
From http://developer.android.com/guide/developing/devices/emulator.html#emulatornetworking: if you want to communicate from within the emulator to the local host, use IP 127.0.0.1 on the local host and use IP 10.0.2.2 in Android. This should let you communicate between the Android client and the local host server.
You want to run the server part on the Android? I guess not, and in such case using loopback address is not really going to work, as loopback interface on the Android system loops back to the Android machine itself, it is not routed to the outside.
For the serverAddr, use the #InetSocketAddress(int port) constructor, it specifies the wildcard address and a specific port, meaning it listens on all the interfaces of the machine.
Edit: For best results, on the android device use the DNS name of the server to connect to it.
Hay Guys, I'm new to Android but heres what i want to do.
I want to beable to open a connect to a server using a given IP and PORT, then send commands to the server and get data back.
Any ideas what i need to google to help on this? I know how to do it in PHP (using fputs, fgets, and fsockopen).
any help would be brill.
Thanks
Use the java.net classes. Below is a simple example using DatagramSockets:
String cmd("my command");
try {
InetSocketAddress address = new InetSocketAddress("10.1.1.1", 12350);
DatagramPacket request = new DatagramPacket(cmd.getBytes(), cmd.length(), address);
DatagramSocket socket = new DatagramSocket();
socket.send(request);
} catch (SocketException e) {
...
}
} catch (IOException e) {
...
}
}
Other Java samples can be found here: