Я делаю приложение для Android, в которое хочу загрузить данные json. Моя спецификация заключается в том, что если есть доступ в Интернет, то загружать данные с URL-адреса, который я предоставляю.
Если нет интернета, то загрузите локальный файл json.txt.
Мое приложение может загружать данные с URL-адреса, если есть подключение к Интернету, и оно может загружать локальные данные json, если подключение к Интернету отсутствует.
Однако в таком метасостоянии мое приложение падает.
Журнал
07-14 09:56:21.258 22499-28349/scientist.jobless.foodmana E/log_tag﹕ Error in http connection java.net.UnknownHostException: Unable to resolve host "lit-hamlet-6856.herokuapp.com": No address associated with hostname
07-14 09:56:21.258 22499-28349/scientist.jobless.foodmana E/log_tag﹕ Error converting result java.lang.NullPointerException
07-14 09:56:21.258 22499-28349/scientist.jobless.foodmana E/log_tag﹕ Error parsing data org.json.JSONException: End of input at character 0 of
07-14 09:56:21.266 22499-28349/scientist.jobless.foodmana E/AndroidRuntime﹕ FATAL EXCEPTION: AsyncTask #1
java.lang.RuntimeException: An error occured while executing doInBackground()
at android.os.AsyncTask$3.done(AsyncTask.java:299)
at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
at java.util.concurrent.FutureTask.run(FutureTask.java:137)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
at java.lang.Thread.run(Thread.java:856)
Caused by: java.lang.NullPointerException
at scientist.jobless.foodmana.JsonLoadSubFirstFirst$DownloadJSON.doInBackground(JsonLoadSubFirstFirst.java:239)
at scientist.jobless.foodmana.JsonLoadSubFirstFirst$DownloadJSON.doInBackground(JsonLoadSubFirstFirst.java:215)
at android.os.AsyncTask$2.call(AsyncTask.java:287)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
at java.util.concurrent.FutureTask.run(FutureTask.java:137)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
at java.lang.Thread.run(Thread.java:856)
07-14 09:56:21.878 22499-22499/scientist.jobless.foodmana E/WindowManager﹕ Activity scientist.jobless.foodmana.JsonLoadSubFirstFirst has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@5374c12c that was originally added here
android.view.WindowLeaked: Activity scientist.jobless.foodmana.JsonLoadSubFirstFirst has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@5374c12c that was originally added here
at android.view.ViewRootImpl.<init>(ViewRootImpl.java:374)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:292)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:224)
at android.view.WindowManagerImpl$CompatModeWrapper.addView(WindowManagerImpl.java:149)
at android.view.Window$LocalWindowManager.addView(Window.java:547)
at android.app.Dialog.show(Dialog.java:277)
at scientist.jobless.foodmana.MyCustomProgressDialog.show(MyCustomProgressDialog.java:43)
at scientist.jobless.foodmana.JsonLoadSubFirstFirst$DownloadJSON.onPreExecute(JsonLoadSubFirstFirst.java:227)
at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:586)
at android.os.AsyncTask.execute(AsyncTask.java:534)
at scientist.jobless.foodmana.JsonLoadSubFirstFirst.onCreate(JsonLoadSubFirstFirst.java:74)
at android.app.Activity.performCreate(Activity.java:5008)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
at android.app.ActivityThread.access$600(ActivityThread.java:130)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4745)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
Ниже приведен мой код Java, где я проверяю тип подключения.
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Get the view from listview_main.xml
setContentView(R.layout.listview_main);
// Execute DownloadJSON AsyncTask
ConnectivityManager connec = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);
if (connec != null && (
(connec.getNetworkInfo(ConnectivityManager.TYPE_WIFI).getState() == NetworkInfo.State.CONNECTED) ||
(connec.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).getState() == NetworkInfo.State.CONNECTED))) {
new DownloadJSON(this).execute();
//You are connected, do something online.
} else if (connec != null && (
(connec.getNetworkInfo(ConnectivityManager.TYPE_WIFI).getState() == NetworkInfo.State.DISCONNECTED) ||
(connec.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).getState() == NetworkInfo.State.DISCONNECTED ))) {
//Not connected.
Toast.makeText(getApplicationContext(), "You must be connected to the internet", Toast.LENGTH_LONG).show();
new LocalDownloadJSON().execute();
}
else if (connec != null && (
(connec.getNetworkInfo(ConnectivityManager.TYPE_WIFI).getState() == NetworkInfo.State.UNKNOWN) ||
(connec.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).getState() == NetworkInfo.State.UNKNOWN ))) {
//i want to load local json data here
}
}
Мой вопрос в том, как обрабатывать это метасостояние соединения, как я показал на картинке эмулятора.
я пробовал этот ответ, но я получаю сообщение об ошибке isNetworkAvailable(context), поскольку не могу решить метод isNetworkAvailable.
Есть ли вообще по этому коду??
(connec != null && (
(connec.getNetworkInfo(ConnectivityManager.TYPE_WIFI).getState() == NetworkInfo.State.UNKNOWN) ||
(connec.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).getState() == NetworkInfo.State.UNKNOWN )))
LocalJsonDownload.java
private class LocalDownloadJSON extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
pd = new ProgressDialog(JsonLoadSubFirstFirst.this);
pd.setMessage("Loading...");
pd.setProgressStyle(ProgressDialog.STYLE_SPINNER);
pd.setIndeterminate(true);
pd.setCancelable(false);
pd.show();
}
@Override
protected Void doInBackground(Void... params) {
// Create an array
localarraylist = new ArrayList<HashMap<String, String>>();
// Retrieve JSON Objects from the given URL address
StringBuffer sb = new StringBuffer();
BufferedReader br = null;
try {
br = new BufferedReader(new InputStreamReader(getAssets().open("localfood.txt")));
String temp;
while ((temp = br.readLine()) != null)
sb.append(temp);
}
catch (IOException e)
{
e.printStackTrace();
}
finally
{
try
{
br.close();
}
catch (IOException e)
{
e.printStackTrace();
}
}
myjsonstring = sb.toString();
try{
JSONObject jsonObj = new JSONObject(myjsonstring);
JSONArray Attendance = jsonObj.getJSONArray("events");
for (int i = 0; i < Attendance.length(); i++)
{
JSONObject a = Attendance.getJSONObject(i);
String Name = a.getString("Name");
String time = a.getString("Time");
String ingredients = a.getString("ingredients");
String Serves = a.getString("Serves");
String descr = a.getString("Description");
HashMap<String, String> contact = new HashMap<String, String>();
// adding each child node to HashMap key => value
contact.put("Name", Name);
contact.put("Time", time);
contact.put("ingredients", ingredients);
contact.put("Serves", Serves);
contact.put("Description", descr);
// adding contact to contact list
localarraylist.add(contact);
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(Void args) {
Toast.makeText(getApplicationContext(),"Loading local data dishes, please connect o internet to load new dishes",Toast.LENGTH_LONG).show();
// Locate the listview in listview_main.xml
//setContentView(R.layout.listview_main);
listview = (ListView) findViewById(R.id.listview);
// Pass the results into ListViewAdapter.java
adapter = new ListViewAdapter(JsonLoadSubFirstFirst.this, localarraylist);
// Set the adapter to the ListView
listview.setAdapter(adapter);
// Close the progressdialog
// mProgressDialog.dismiss();
// textView.setVisibility(View.VISIBLE);
pd.dismiss();
super.onPostExecute(args);
}
}
