问题
App crashes while sending data over a socket using wifi p2p connection
I am testing a simple chat application between HTC_Desire_10 pro (running Android 6.0) and OPPO A83 (running Android 7.1.1). I have the same app running on the two devices. The app first turns wifi on, then starts discovering peers on a users click event. The user can choose the device they want to connect to from a dynamically generated peer list. The two devices are able to connect successfully. I am able to send a text message from the HTC to OPPO phone but when I try to send a message from the OPPO phone, the app crashes.
This is the code that assigns which device will be the host or client
WifiP2pManager.ConnectionInfoListener connectionInfoListener = new WifiP2pManager.ConnectionInfoListener() {
@Override
public void onConnectionInfoAvailable(WifiP2pInfo wifiP2pInfo) {
final InetAddress groupOwnerAddress = wifiP2pInfo.groupOwnerAddress;
if(wifiP2pInfo.groupFormed&&wifiP2pInfo.isGroupOwner) {
ConnectionStatus.setText("Host");
serverClass = new ServerClass();
serverClass.start();
} else if(wifiP2pInfo.groupFormed) {
ConnectionStatus.setText("Client");
clientClass = new ClientClass(groupOwnerAddress);
clientClass.start();
}
}
};
And this is the code for the ServerThread, ClientThread and SendRecieveThread
public class ServerClass extends Thread{
Socket socket;
ServerSocket serverSocket;
@Override
public void run() {
try {
serverSocket = new ServerSocket(8888);
socket = serverSocket.accept();
sendReceive = new SendReceive(socket);
sendReceive.start();
} catch (IOException e) {
e.printStackTrace();
}
}
}
private class SendReceive extends Thread {
private Socket socket;
private InputStream inputStream;
private OutputStream outputStream;
public SendReceive(Socket skt) {
socket = skt;
try {
inputStream = socket.getInputStream();
outputStream = socket.getOutputStream();
} catch (IOException e) {
e.printStackTrace();
}
}
@Override
public void run() {
byte[] buffer = new byte[1024];
int bytes;
while (socket!=null) {
try {
bytes = inputStream.read(buffer);
if(bytes>0) {
handler.obtainMessage(MESSAGE_READ,bytes,-1,buffer).sendToTarget();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
public void write(byte[] bytes) {
try {
outputStream.write(bytes);
} catch (IOException e) {
e.printStackTrace();
}
}
}
public class ClientClass extends Thread {
Socket socket;
String hostAdd;
public ClientClass(InetAddress hostAddress) {
hostAdd = hostAddress.getHostAddress();
socket = new Socket();
}
@Override
public void run() {
try {
socket.connect(new InetSocketAddress(hostAdd, 8888),1000);
sendReceive = new SendReceive(socket);
sendReceive.start();
} catch (IOException e) {
e.printStackTrace();
}
}
}
The SendRecieve functionality gets invoked when a user clicks a send message button.
btnSend.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String msg = writeMsg.getText().toString();
sendReceive.write(msg.getBytes());
}
});
I've run the app in USB-debugging mode using android studio and obtained the crash report from the adb logcat command:
--------- beginning of crash
03-27 22:16:54.115 6904 6904 E AndroidRuntime: FATAL EXCEPTION: main
03-27 22:16:54.115 6904 6904 E AndroidRuntime: Process: june.androidapps.clatt, PID: 6904
03-27 22:16:54.115 6904 6904 E AndroidRuntime: android.os.NetworkOnMainThreadException
03-27 22:16:54.115 6904 6904 E AndroidRuntime: at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1318)
03-27 22:16:54.115 6904 6904 E AndroidRuntime: at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:111)
03-27 22:16:54.115 6904 6904 E AndroidRuntime: at java.net.SocketOutputStream.write(SocketOutputStream.java:145)
03-27 22:16:54.115 6904 6904 E AndroidRuntime: at june.androidapps.clatt.MainActivity$SendReceive.write(MainActivity.java:264)
03-27 22:16:54.115 6904 6904 E AndroidRuntime: at june.androidapps.clatt.MainActivity$5.onClick(MainActivity.java:135)
03-27 22:16:54.115 6904 6904 E AndroidRuntime: at android.view.View.performClick(View.java:5773)
03-27 22:16:54.115 6904 6904 E AndroidRuntime: at android.view.View$PerformClick.run(View.java:23035)
03-27 22:16:54.115 6904 6904 E AndroidRuntime: at android.os.Handler.handleCallback(Handler.java:836)
03-27 22:16:54.115 6904 6904 E AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:103)
03-27 22:16:54.115 6904 6904 E AndroidRuntime: at android.os.Looper.loop(Looper.java:232)
03-27 22:16:54.115 6904 6904 E AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:6802)
03-27 22:16:54.115 6904 6904 E AndroidRuntime: at java.lang.reflect.Method.invoke(Native Method)
03-27 22:16:54.115 6904 6904 E AndroidRuntime: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1103)
03-27 22:16:54.115 6904 6904 E AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:964)
03-27 22:17:06.089 7393 7393 E AndroidRuntime: FATAL EXCEPTION: main
...
Can anyone please explain why the app behaves this way? I have gone through the entire logs for about an hour and I cant seem to find what's exactly going wrong in my code. Any help will be appreciated.
with regards.
回答1:
Turns out the write() method was trying to write to the sockets' outputStream before the socket connection was set up. I disabled the send message button by default, then used AsyncTask to setup the socket connection in a background thread. Once the doInBackground() method finishes executing it makes a call to onPostExecute() which in turn uses socket.getInputStream() and socket.getOutputStream() to setup the sockets' inputStream and outputStream respectively and also enables the send message button. The send message button has a OnClickListener which makes a call to the write() method on a click event.
Disable send message button by default
btnSend.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String msg = writeMsg.getText().toString();
byte[] bytes =msg.getBytes();
btnSend.setVisibility(View.INVISIBLE);
if(userType.equals("server")) {
serverClass.writeData(bytes);
} else {
clientClass.writeData(bytes);
}
}
});
Server Thread
public class Server extends AsyncTask<String, Integer, Boolean> {
Socket socket;
ServerSocket serverSocket;
InputStream inputStream;
OutputStream outputStream;
@Override
protected Boolean doInBackground(String... strings) {
boolean result = true;
try {
serverSocket = new ServerSocket(8888);
socket = serverSocket.accept();
} catch (IOException e) {
result = false;
e.printStackTrace();
}
return result;
}
public void writeData(final byte[] bytes) {
new Thread(new Runnable() {
@Override
public void run() {
try {
outputStream.write(bytes);
} catch (IOException e) {
e.printStackTrace();
}
}
}).start();
btnSend.setVisibility(View.VISIBLE);
}
@Override
protected void onPostExecute(Boolean result) {
if(result) {
try {
inputStream = socket.getInputStream();
outputStream = socket.getOutputStream();
} catch (IOException e) {
e.printStackTrace();
}
//listener
new Thread(new Runnable(){
public void run() {
byte[] buffer = new byte[1024];
int x;
while (socket!=null) {
try {
x = inputStream.read(buffer);
if(x>0) {
handler.obtainMessage(MESSAGE_READ,x,-1,buffer).sendToTarget();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
}).start();
btnSend.setVisibility(View.VISIBLE);
} else {
Toast.makeText(getApplicationContext(),"could not create sockets",Toast.LENGTH_SHORT).show();
//restart socket assignment process
}
}
}
Client Thread
public class Client extends AsyncTask<String, Integer, Boolean> {
Socket socket;
String hostAdd;
InputStream inputStream;
OutputStream outputStream;
public Client(InetAddress hostAddress) {
hostAdd = hostAddress.getHostAddress();
socket = new Socket();
}
@Override
protected Boolean doInBackground(String... strings) {
boolean result = false;
try {
socket.connect(new InetSocketAddress(hostAdd, 8888), 5000);
result = true;
return result;
} catch (IOException e) {
e.printStackTrace();
result = false;
return result;
}
}
public void writeData(final byte[] bytes) {
new Thread(new Runnable() {
@Override
public void run() {
try {
outputStream.write(bytes);
} catch (IOException e) {
e.printStackTrace();
}
}
}).start();
btnSend.setVisibility(View.VISIBLE);
}
@Override
protected void onPostExecute(Boolean result) {
if(result) {
try {
inputStream = socket.getInputStream();
outputStream = socket.getOutputStream();
} catch (IOException e) {
e.printStackTrace();
}
new Thread(new Runnable(){
public void run() {
byte[] buffer = new byte[1024];
int x;
while (socket!=null) {
try {
x = inputStream.read(buffer);
if(x>0) {
handler.obtainMessage(MESSAGE_READ,x,-1,buffer).sendToTarget();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
}).start();
btnSend.setVisibility(View.VISIBLE);
} else {
Toast.makeText(getApplicationContext(),"could not create sockets",Toast.LENGTH_SHORT).show();
//restart socket assignment process
}
}
}
回答2:
my is showing error on ServerClass.start() and ClientClass.start() method, what did you do with this?
来源：https://stackoverflow.com/questions/55387403/app-crash-while-sending-data-over-a-socket-using-wifip2p-connection