I'm using an asynctask to download an xml from an given URL. I get the url from the preferencescreen. N
Now i'm trying to catch some errors so the app doesn't crash but gives a nice toast with the error.
It works already for if the user forgets the 'http://' before the URL. But when the URL is good formed but there is nothing to download the app still crashes and I don't know how to catch this error: i thought the IOException would catch this error but it doesn't.
@Override
protected void onPreExecute() {
progressDialog = new ProgressDialog(mContext);
progressDialog.setTitle("XML downloaden");
progressDialog.setMessage("Downloading xml:");
progressDialog.setMax(100);
progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
progressDialog.show();
}
@Override
protected Void doInBackground(Void... params) {
FileOutputStream fos = null;
InputStream inputStream = null;
HttpURLConnection conn = null;
try {
fos = mContext.openFileOutput("xmlapp.xml", Context.MODE_PRIVATE);
SharedPreferences prefs = PreferenceManager
.getDefaultSharedPreferences(mContext);
String start = prefs.getString("pref_key_url",
"http://sdesigns.be/eindwerk/web6/");
URL url;
url = new URL(start + "source/pages.xml");
conn = (HttpURLConnection) url.openConnection();
byte[] buffer = new byte[64];
if (conn.getResponseCode() == HttpURLConnection.HTTP_OK) {
int bytesToDownload = conn.getContentLength();
int bytesDownloaded = 0;
inputStream = conn.getInputStream();
int len = 0;
while ((len = inputStream.read(buffer)) > 0) {
fos.write(buffer, 0, len);
bytesDownloaded += len;
publishProgress((float) bytesDownloaded / bytesToDownload);
}
inputStream.close();
fos.close();
}
} catch (MalformedURLException e) {
this.e = e;
} catch (IOException e) {
this.e = e;
}
finally {
conn.disconnect();
}
return null;
}
@Override
protected void onPostExecute(Void result) {
if (progressDialog != null) {
progressDialog.dismiss();
progressDialog = null;
}
if (e == null) {
List<String> images = new XmlParserSax(mContext).getImagesList();
DownloadImages di = new DownloadImages(mContext);
di.execute(images);
} else {
Toast.makeText(mContext,
"Check the url!" + e.toString(),
Toast.LENGTH_LONG).show(); //show the error
}
}
EDIT
Stacktrace:
04-19 10:18:40.904: E/WindowManager(2425): Activity com.example.eindwerkappv1.Preferences has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@41a97848 that was originally added here
04-19 10:18:40.904: E/WindowManager(2425): android.view.WindowLeaked: Activity com.example.eindwerkappv1.Preferences has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@41a97848 that was originally added here
04-19 10:18:40.904: E/WindowManager(2425): at android.view.ViewRootImpl.<init>(ViewRootImpl.java:344)
04-19 10:18:40.904: E/WindowManager(2425): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:267)
04-19 10:18:40.904: E/WindowManager(2425): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:215)
04-19 10:18:40.904: E/WindowManager(2425): at android.view.WindowManagerImpl$CompatModeWrapper.addView(WindowManagerImpl.java:140)
04-19 10:18:40.904: E/WindowManager(2425): at android.view.Window$LocalWindowManager.addView(Window.java:537)
04-19 10:18:40.904: E/WindowManager(2425): at android.app.Dialog.show(Dialog.java:278)
04-19 10:18:40.904: E/WindowManager(2425): at com.example.eindwerkappv1.DownloadXml.onPreExecute(DownloadXml.java:38)
04-19 10:18:40.904: E/WindowManager(2425): at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:561)
04-19 10:18:40.904: E/WindowManager(2425): at android.os.AsyncTask.execute(AsyncTask.java:511)
04-19 10:18:40.904: E/WindowManager(2425): at com.example.eindwerkappv1.Preferences$1.onPreferenceClick(Preferences.java:48)
04-19 10:18:40.904: E/WindowManager(2425): at android.preference.Preference.performClick(Preference.java:941)
04-19 10:18:40.904: E/WindowManager(2425): at android.preference.PreferenceScreen.onItemClick(PreferenceScreen.java:202)
04-19 10:18:40.904: E/WindowManager(2425): at android.widget.AdapterView.performItemClick(AdapterView.java:292)
04-19 10:18:40.904: E/WindowManager(2425): at android.widget.AbsListView.performItemClick(AbsListView.java:1068)
04-19 10:18:40.904: E/WindowManager(2425): at android.widget.AbsListView$PerformClick.run(AbsListView.java:2525)
04-19 10:18:40.904: E/WindowManager(2425): at android.widget.AbsListView$1.run(AbsListView.java:3186)
04-19 10:18:40.904: E/WindowManager(2425): at android.os.Handler.handleCallback(Handler.java:605)
04-19 10:18:40.904: E/WindowManager(2425): at android.os.Handler.dispatchMessage(Handler.java:92)
04-19 10:18:40.904: E/WindowManager(2425): at android.os.Looper.loop(Looper.java:137)
04-19 10:18:40.904: E/WindowManager(2425): at android.app.ActivityThread.main(ActivityThread.java:4441)
04-19 10:18:40.904: E/WindowManager(2425): at java.lang.reflect.Method.invokeNative(Native Method)
04-19 10:18:40.904: E/WindowManager(2425): at java.lang.reflect.Method.invoke(Method.java:511)
04-19 10:18:40.904: E/WindowManager(2425): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:823)
04-19 10:18:40.904: E/WindowManager(2425): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:590)
04-19 10:18:40.904: E/WindowManager(2425): at dalvik.system.NativeStart.main(Native Method)
You may want to account for the possibility of the Socket timing out by using conn.setReadTimeout(10000); before you open the connection, then add a catch clause to handle SocketTimeoutException. Note my choice of 10000ms for the timeout is arbitrary.
One main problem is you're not properly handling what happens when the server returns a response other than HTTP_OK. Even if (conn.getResponseCode() == HttpURLConnection.HTTP_OK) is false, there will be no exceptions caught. MalformedURLException is thrown only for formatting errors in the URL, and IOException in situations where you try to read from a closed socket, or something similar. There is nothing to catch HTTP_NOT_FOUND. A quick fix to this I guess would be adding an else clause to if(conn.getResponseCode() == HttpURLConnection.HTTP_OK).
else {
e = new Exception();
}
This way, e will not be null in onPostExecute(). This of course is not really good practice, but it will work with your code.
Edit: The following code worked for me just fine. I had to fill in a few areas you didn't include.
private class DownloadTask extends AsyncTask<Void, Float, Void> {
Context mContext;
ProgressDialog progressDialog;
Exception e;
DownloadTask(Context context) {
mContext = context;
}
@Override
protected void onPreExecute() {
progressDialog = new ProgressDialog(mContext);
progressDialog.setTitle("XML downloaden");
progressDialog.setMessage("Downloading xml:");
progressDialog.setMax(100);
progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
progressDialog.show();
}
@Override
protected void onProgressUpdate(Float... values) {
for( float val : values) {
progressDialog.setProgress((int)(val*100f));
}
}
@Override
protected Void doInBackground(Void... params) {
FileOutputStream fos = null;
InputStream inputStream = null;
HttpURLConnection conn = null;
try {
fos = mContext.openFileOutput("xmlapp.xml", Context.MODE_PRIVATE);
SharedPreferences prefs = PreferenceManager
.getDefaultSharedPreferences(mContext);
String start = prefs.getString("pref_key_url",
"http://sdesigns.be/eindwerk/web6/");
URL url;
url = new URL(start);
conn = (HttpURLConnection) url.openConnection();
conn.setDoInput(true);
conn.setRequestMethod("GET");
conn.setReadTimeout(50000);
conn.connect();
byte[] buffer = new byte[64];
if (conn.getResponseCode() == HttpURLConnection.HTTP_OK) {
int bytesToDownload = conn.getContentLength();
int bytesDownloaded = 0;
inputStream = conn.getInputStream();
int len = 0;
while ((len = inputStream.read(buffer)) > 0) {
fos.write(buffer, 0, len);
bytesDownloaded += len;
publishProgress((float) bytesDownloaded / bytesToDownload);
}
inputStream.close();
fos.close();
} else {
e = new Exception("URL not found.");
}
} catch (Exception e) {
//since you don't differentiate exceptions and just check if e is null, you might as well just have one catch block
this.e = e;
}
finally {
try {
conn.disconnect();
} catch (Exception e) {}
conn = null;
}
return null;
}
@Override
protected void onPostExecute(Void result) {
if (progressDialog != null) {
progressDialog.dismiss();
progressDialog = null;
}
if (e == null) {
Toast.makeText(mContext,
"Success!",
Toast.LENGTH_LONG).show();
List<String> images = new XmlParserSax(mContext).getImagesList();
DownloadImages di = new DownloadImages(mContext);
di.execute(images);
} else {
Toast.makeText(mContext,
"Check the url!" + e.toString(),
Toast.LENGTH_LONG).show(); //show the error
}
}
}