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.toStri开发者_Python百科ng());
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();
}
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