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App crashes when connection is lost while using HttpUrlConnection

i'm making a class that get json data from an external url, it is working fine if there is a connection. also shows an error if there isn't.
the problem is if the connection lost while the class is getting data the app crashes.
here is my code:
//I always check connection before calling the class
class GetPost extends AsyncTask<String, String, String>
{
Context c;
String res;
public GetPost(Context c){
this.c=c;
}
#Override
protected void onPreExecute()
{
super.onPreExecute();
Earn.statu.setText("Loading post...");
}
#Override
protected String doInBackground(String[] p1)
{
try{
URL u = new URL(p1[0]);
HttpURLConnection con = (HttpURLConnection) u.openConnection();
InputStream is = con.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(is));
res = br.readLine();
}
catch (MalformedURLException e){}
catch (IOException e){}
return res;
}
#Override
protected void onPostExecute(String result)
{
super.onPostExecute(result);
try{
JSONObject jo = new JSONObject(res);
Earn.getVideoData(c,
jo.getString("pid"),
jo.getInt("duration"),
jo.getInt("id")
);
}catch(JSONException a){}
}
so guys is there any solution to prevent the app from crashing?

Set timeout on request by example:
try {
HttpURLConnection con = (HttpURLConnection) new URL(url).openConnection();
con.setRequestMethod("HEAD");
con.setConnectTimeout(5000); //set timeout to 5 seconds
return (con.getResponseCode() == HttpURLConnection.HTTP_OK);
} catch (java.net.SocketTimeoutException e) {
return false;
} catch (java.io.IOException e) {
return false;
}

Android socket principle and exception

i'm begginer with java socket in android. i'm have some problem and need help for solving them.
I'm connect to server Socket with bottom code and every thing is fine. but when call disconnect method and try to connect again i faced with problem such socket is null or BufferedReader object always return null after disconnect and connect again. maybe my disconnect way is wrong. what is the best way for disconnect socket at some time like intrupt internet and connect again?
Here is my code for connecting and disconnecting socket.
public class HelperSocket {
public static Socket socket = null;
public static DataOutputStream writer = null;
public static BufferedReader reader = null;
public static DataInputStream inputStream = null;
public static final String SOCKET_ADDRESS = "aUrlForSocket";
public static final int SOCKET_PORT = 6000;
public static final int SOCKET_TIMEOUT = 30000;
public static Thread clientThread;
public static boolean isConnected = false;
public static boolean connect() {
Utils.Log("StartConnect");
if (!isConnected) {
clientThread = new Thread(new Runnable() {
#Override
public void run() {
try {
InetAddress address = InetAddress.getByName(HelperSocket.SOCKET_ADDRESS);
socket = new Socket(address.getHostAddress(), SOCKET_PORT);
isConnected = true;
socket.setSoTimeout(SOCKET_TIMEOUT);
writer = new DataOutputStream(socket.getOutputStream());
reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
inputStream = new DataInputStream(socket.getInputStream());
while (HelperSocket.isConnected) {
Utils.Log("onWhile" + reader.hashCode());
try {
if (reader.readLine() != null) {
Utils.Log(reader.readLine() + "");
} else {
Utils.Log("getNullFromServer");
//data get null here :)
disconnect();
}
} catch (IOException e) {
Utils.Log("ProblemOnReadData" + e.getMessage());
e.printStackTrace();
}
}
} catch (IOException e) {
Utils.Log("SocketProblemAt connect:" + e.getMessage());
e.printStackTrace();
}
}
});
clientThread.start();
}
return true;
}
public static boolean disconnect() {
isConnected = false;
if (!clientThread.isInterrupted())
clientThread.interrupt();
if (socket != null) {
Utils.Log("SocketAndAllObjectCleared");
try {
socket.shutdownInput();
socket.shutdownOutput();
socket = null;
} catch (IOException e) {
e.printStackTrace();
}
/* stream = null;
reader = null;*/
}
return false;
}
}
I create a reciever in network connectivity change, and need to disconnect socket when device not connect to internet and connect again when internet connection established.
The receiver:
public class BroadcastChangeNet extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
if (Utils.isNetworkConnected()) {
HelperSocket.connect();
Utils.Log("NetWorkConnect");
} else {
HelperSocket.disconnect();
Utils.Log("NetWorkDisConnect");
}
}
}
Checking network situation:
public static boolean isNetworkConnected() {
ConnectivityManager conMgr =
(ConnectivityManager) ApplicationClass.context.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo i = conMgr.getActiveNetworkInfo();
if (i == null)
return false;
if (!i.isConnected())
return false;
if (!i.isAvailable())
return false;
return true;
}

From my point of view you simply need to create saprate Jave class, below is my code that i tested successfully,
import android.content.Context;
import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.Socket;
import java.net.SocketException;
import java.net.UnknownHostException;
/**
* Created by Kintan Patel on 01-08-2016.
*/
public class SocketConnection {
private Socket socket = null;
private OutputStream outputStream;
private DataOutputStream dataOutputStream;
private SessionHelper helper;
public String EstablishConnection(String token) {
// token = your message that write on socket server
String response;
try {
//socket = new Socket("192.168.0.24", 2129); // Testing Server
socket = new Socket("Your IpAddress", PORT NO);
outputStream = socket.getOutputStream();
dataOutputStream = new DataOutputStream(outputStream);
dataOutputStream.writeUTF(token);
BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
response = br.readLine();
} catch (UnknownHostException e) {
e.printStackTrace();
response = "UnknownHostException: " + e.toString();
return null;
} catch (SocketException e) {
e.printStackTrace();
response = "Sorry Fail to connect";
return null;
} catch (IOException e) {
// TODO Auto-generated catch block
// e.printStackTrace();
response = "Sorry Fail to connect";
return null;
} catch (Exception e) {
e.printStackTrace();
response = "Server Break";
return null;
} finally {
if (socket != null) {
try {
socket.close();
outputStream.close();
dataOutputStream.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
return response;
}
}
Now from your main class simply create the object of SocketConnection class and use EstablishConnection() method,
eg :
SocketConnection connection = new SocketConnection();
String token = "message that you want to write on server";
String response = connecation.EstablishConnection(token);
if you want to use AsynkTask than below is AsynkTask code :
private class ActivationTask extends AsyncTask<String, String, String> {
#Override
protected String doInBackground(String... params) {
SocketConnection connection = new SocketConnection();
String token = "getActivation|" + params[0] + "|";
return connection.EstablishConnection(token);
}
#Override
protected void onPreExecute() {
super.onPreExecute();
progressDialog.show();
}
#Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
progressDialog.dismiss();
if (s != null) {
Log.e("RESULT" , s);
}
}
}

Why i'm getting timeout when trying to connect from my android device to the web server on my pc?

The web server on the pc is in c#
In the form1 constructor:
var ws = new WebServer(
request => Task.Run(() => SendResponseAsync(request)),
"http://+:8098/");
ws.Run();
This two methods
public static string GetLocalIPAddress()
{
var host = Dns.GetHostEntry(Dns.GetHostName());
foreach (var ip in host.AddressList)
{
if (ip.AddressFamily == AddressFamily.InterNetwork)
{
return ip.ToString();
}
}
throw new Exception("Local IP Address Not Found!");
}
public void Send(string ipaddress)
{
UdpClient client = new UdpClient();
IPEndPoint ip = new IPEndPoint(IPAddress.Broadcast, 15000);
byte[] bytes = Encoding.ASCII.GetBytes(ipaddress);
client.Send(bytes, bytes.Length, ip);
client.Close();
}
Then in timer tick event interval set to 1000ms
int countsends = 0;
private void timer2_Tick(object sender, EventArgs e)
{
if (countsends == 10)
{
Send(localipadd);
countsends = 0;
}
countsends += 1;
}
And the WebServer class
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net;
using System.Threading;
namespace Automatic_Record
{
class WebServer
{
private readonly HttpListener _listener = new HttpListener();
private readonly Func<HttpListenerRequest, Task<string>> _responderMethod;
public WebServer(string[] prefixes, Func<HttpListenerRequest, Task<string>> method)
{
try
{
if (!HttpListener.IsSupported)
throw new NotSupportedException(
"Needs Windows XP SP2, Server 2003 or later.");
// URI prefixes are required, for example
// "http://localhost:8080/index/".
if (prefixes == null || prefixes.Length == 0)
throw new ArgumentException("prefixes");
// A responder method is required
if (method == null)
throw new ArgumentException("method");
foreach (string s in prefixes)
_listener.Prefixes.Add(s);
_responderMethod = method;
_listener.Start();
}
catch(AccessViolationException err)
{
string error = err.StackTrace;
}
}
}
On the pc side the c# i'm not getting any errors or exceptions and using break point i can see the pc ip on the network on the router on the method Send on variable ipaddress it's value is 10.0.0.1 i also logged in to my router settings and i saw that the pc is on 10.0.0.1
Now the java side in the android-studio where i'm trying to get the pc ip and to connect to it:
At the top of mainactivity: ( I tried before port 8098 but it didn't work so i tried 15000 but also didn't work still getting timeout message )
private String[] ipaddresses = new String[]{
"http://10.0.0.1:15000/?cmd=nothing"
};
Then a button click method calling from onCreate
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
addListenerOnButton();
currentActivity = this;
initTTS();
}
The addListenerOnButton
public void addListenerOnButton()
{
btnClick = (Button) findViewById(R.id.connecttoserverbutton);
btnClick.setOnClickListener(new OnClickListener()
{
byte[] response = null;
#Override
public void onClick(View arg0)
{
text = (TextView) findViewById(R.id.statusTextView);
Thread t = new Thread(new Runnable()
{
#Override
public void run()
{
for (int i = 0; i < ipaddresses.length; i++)
{
counter = i;
try
{
response = Get(ipaddresses[i]);
}
catch (Exception e)
{
String err = e.toString();
}
if (response!=null)
{
try
{
final String a = new String(response, "UTF-8");
text.post(new Runnable()
{
#Override
public void run()
{
text.setText(a + " Oמ " + ipaddresses[counter]);
}
});
iptouse = ipaddresses[i].substring(0,ipaddresses[i].lastIndexOf("=")+1);
connectedtoipsuccess = true;
Logger.getLogger("MainActivity(inside thread)").info(a);
} catch (UnsupportedEncodingException e)
{
e.printStackTrace();
Logger.getLogger("MainActivity(inside thread)").info("encoding exception");
}
Logger.getLogger("MainActivity(inside thread)").info("test1");
break;
}
else
{
}
}
counter = 0;
if (response == null)
{
text.post(new Runnable()
{
#Override
public void run()
{
text.setText("Connection Failed");
}
});
}
}
});
t.start();
}
});
}
And last the Get method
private byte[] Get(String urlIn)
{
URL url = null;
String urlStr = urlIn;
if (urlIn!=null)
urlStr=urlIn;
try
{
url = new URL(urlStr);
} catch (MalformedURLException e)
{
e.printStackTrace();
return null;
}
HttpURLConnection urlConnection = null;
try
{
urlConnection = (HttpURLConnection) url.openConnection();
InputStream in = new BufferedInputStream(urlConnection.getInputStream());
byte[] buf=new byte[10*1024];
int szRead = in.read(buf);
byte[] bufOut;
if (szRead==10*1024)
{
throw new AndroidRuntimeException("the returned data is bigger than 10*1024.. we don't handle it..");
}
else
{
bufOut = Arrays.copyOf(buf, szRead);
}
return bufOut;
}
catch (IOException e)
{
e.printStackTrace();
return null;
}
finally
{
if (urlConnection!=null)
urlConnection.disconnect();
}
}
My android device is also connected to the same network on the router with wifi i checked on the router settings and i see my device.
I used a break point on the android-studio side inside the Get method.
It's getting to the line:
InputStream in = new BufferedInputStream(urlConnection.getInputStream());
Then i click continue and that's it here it's hanging and instead keep going to the next line byte[] buf=new byte[10*1024]; after about 30 seconds it's jumping to: e.printStackTrace();
android.system.ErrnoException: connect failed: ETIMEDOUT (Connection timed out)
failed to connect to /10.0.0.1 (port 15000): connect failed: ETIMEDOUT (Connection timed out)
I can't see any exceptions in the logcat.

How to stop HttpURLConnection.getInputStream()?

Below is my code:
private HttpURLConnection connection;
private InputStream is;
public void upload() {
try {
URL url = new URL(URLPath);
connection = (HttpURLConnection) url.openConnection();
connection.setConnectTimeout(30000);
connection.setReadTimeout(30000);
connection.setDoInput(true);
connection.setUseCaches(false);
connection.connect();
is = connection.getInputStream();
} catch (Exception e) {
e.printStackTrace();
}
}
public void stopupload() {
connection = null;
is = null;
}
When I upload file, the line is = connection.getInputStream(); will spend a lot of time to get reply. So I want to implement a stop function as stopupload(). But if I call stopupload() while the code is handling at line is = connection.getInputStream();, it still needs to wait for its reply.
I want to stop waiting at once while implement stopupload(). How can I do it?

But if I call stopupload() while the code is handling at line is =
connection.getInputStream();, it still needs to wait for its reply.
Starting from HoneyComb, all network operations are not allowed to be executed over main thread. To avoid getting NetworkOnMainThreadException, you may use Thread or AsyncTask.
I want to stop waiting at once while implement stopupload(). How can I
do it?
Below code gives the user to stop uploading after 2 seconds, but you can modify the sleep times (should be less than 5 seconds) accordingly.
upload:
public void upload() {
try {
URL url = new URL(URLPath);
connection = (HttpURLConnection) url.openConnection();
connection.setConnectTimeout(30000);
connection.setReadTimeout(30000);
connection.setDoInput(true);
connection.setUseCaches(false);
connection.connect();
// run uploading activity within a Thread
Thread t = new Thread() {
public void run() {
is = connection.getInputStream();
if (is == null) {
throw new RuntimeException("stream is null");
}
// sleep 2 seconds before "stop uploading" button appears
mHandler.postDelayed(new Runnable() {
public void run() {
mBtnStop.setVisibility(View.VISIBLE);
}
}, 2000);
}
};
t.start();
} catch (Exception e) {
e.printStackTrace();
} finally {
if (is != null) {
try {
is.close();
} catch (IOException e) {
}
}
if (connection != null) {
connection.disconnect();
}
}
}
onCreate:
#Override
public void onCreate(Bundle savedInstanceState) {
// more codes...
Handler mHandler = new Handler();
mBtnStop = (Button) findViewById(R.id.btn_stop);
mBtnStop.setBackgroundResource(R.drawable.stop_upload);
mBtnStop.setOnClickListener(mHandlerStop);
mBtnStop.setVisibility(View.INVISIBLE);
View.OnClickListener mHandlerStop = new View.OnClickListener() {
#Override
public void onClick(View v) {
stopUpload(); // called when "stop upload" button is clicked
}
};
// more codes...
}

private HttpURLConnection connection;
private InputStream is;
public void upload() {
try {
URL url = new URL(URLPath);
connection = (HttpURLConnection) url.openConnection();
connection.setConnectTimeout(30000);
connection.setReadTimeout(30000);
connection.setDoInput(true);
connection.setUseCaches(false);
connection.connect();
Thread t = new Thread() {
public void run() {
is = connection.getInputStream();
}
};
t.start()
} catch (Exception e) {
e.printStackTrace();
}catch (InterruptedException e) {
stopupload(connection ,is, t);
}
}
public void stopupload(HttpURLConnection connection ,InputStream is,Thread t) {
if(connection != null ){
try {
t.interupt();
running = false;
connection=null;
is=null;
} catch (Exception e) {
}
}
}

Wrap the code that uses HttpURLConnection inside a Future, as described here.

Android: handle unexpected internet disconnect while downloading data

I have here a function that downloads data from a remote server to file. I am still not confident with my code. My question is, what if while reading the stream and saving the data to a file and suddenly I was disconnected in the internet, will these catch exceptions below can really catch that kind of incident? If not, can you suggest how to handle this kind of incident?
Note: I call this function in a thread so that the UI won't be blocked.
public static boolean getFromRemote(String link, String fileName, Context context){
boolean dataReceived = false;
ConnectivityManager connec = (ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE);
if (connec.getNetworkInfo(0).isConnected() || connec.getNetworkInfo(1).isConnected()){
try {
HttpClient httpClient = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(link);
HttpParams params = httpClient.getParams();
HttpConnectionParams.setConnectionTimeout(params, 30000);
HttpConnectionParams.setSoTimeout(params, 30000);
HttpResponse response;
response = httpClient.execute(httpGet);
int statusCode = response.getStatusLine().getStatusCode();
if (statusCode == 200){
HttpEntity entity = response.getEntity();
InputStream in = null;
OutputStream output = null;
try{
in = entity.getContent();
String secondLevelCacheDir = context.getCacheDir() + fileName;
File imageFile = new File(secondLevelCacheDir);
output= new FileOutputStream(imageFile);
IOUtilities.copy(in, output);
output.flush();
} catch (IOException e) {
Log.e("SAVING", "Could not load xml", e);
} finally {
IOUtilities.closeStream(in);
IOUtilities.closeStream(output);
dataReceived = true;
}
}
}catch (SocketTimeoutException e){
//Handle not connecting to client !!!!
Log.d("SocketTimeoutException Thrown", e.toString());
dataReceived = false;
} catch (ClientProtocolException e) {
//Handle not connecting to client !!!!
Log.d("ClientProtocolException Thrown", e.toString());
dataReceived = false;
}catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
dataReceived = false;
Log.d("MalformedURLException Thrown", e.toString());
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
dataReceived = false;
Log.d("IOException Thrown", e.toString());
}
}
return dataReceived;
}

I use the following snippet to check if Network is Available before I start a network communication(Prevention better than cure?). Once the communication starts, I can only hope that the network remains available throughout. If not, I would catch Exception thrown and display a message to the user.
public boolean isNetworkAvailable() {
Context context = getApplicationContext();
ConnectivityManager connectivity = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
if (connectivity == null) {
boitealerte(this.getString(R.string.alert),"getSystemService rend null");
} else {
NetworkInfo[] info = connectivity.getAllNetworkInfo();
if (info != null) {
for (int i = 0; i < info.length; i++) {
if (info[i].getState() == NetworkInfo.State.CONNECTED) {
return true;
}
}
}
}
return false;
}
You can attach a DefaultThreadHandler with any thread which would be used if any exception go uncaught in the exception-raising code.
[EDIT: Adding sample code]
//attaching a Handler with a thread using the static function
Thread.setDefaultUncaughtExceptionHandler(handler);
//creating a Handler
private Thread.UncaughtExceptionHandler handler=
new Thread.UncaughtExceptionHandler() {
public void uncaughtException(Thread thread, Throwable ex) {
Log.e(TAG, "Uncaught exception", ex);
showDialog(ex);
}
};
void showDialog(Throwable t) {
AlertDialog.Builder builder=new AlertDialog.Builder(mContext);
builder
.setTitle("Exception")
.setMessage(t.toString())
.setPositiveButton("Okay", null)
.show();
}