问题
My goal is to download some information from a PHP web server. I have created a service to run 24 hours. App start this service using alaram manager class.
Intent ishintent = new Intent(this, AlarmReceiver.class);
PendingIntent pintent = PendingIntent.getBroadcast(this, 2523, ishintent, PendingIntent.FLAG_UPDATE_CURRENT);
AlarmManager alarm = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
alarm.setInexactRepeating(AlarmManager.RTC_WAKEUP, System.currentTimeMillis(), 15000, pintent);
AlarmReceiver.class
public class AlarmReceiver extends BroadcastReceiver{
@Override
public void onReceive(Context context, Intent intent)
{
SharedPreferences settings = context.getSharedPreferences("local", 0);
boolean TaskEnabled = settings.getBoolean("taskenabled", false);
if (!TaskEnabled) {
Intent myService = new Intent(context, ServiceClass.class);
context.startService(myService);
}
}
}
Service class have an AsyncTask which download data from internet using HttpURLConnection.
@Override
public void onStart(Intent intent, int startId) {
super.onStart(intent, startId);
new DownloadInfo().execute("http://example.com/xxx.php");
}
Class DownloadInfo
class DownloadInfo extends AsyncTask<String, String, String> {
@Override
protected String doInBackground(String... url) {
// constants
try {
System.setProperty("http.keepAlive", "false");
HttpURLConnection connection = (HttpURLConnection) new URL(url[0]).openConnection();
connection.setDoOutput(true);
connection.setConnectTimeout(30000); // miliseconds
connection.setRequestMethod("POST");
connection.setRequestProperty("Connection", "Keep-Alive");
connection.setRequestProperty("Charset", "UTF-8");
connection.setRequestProperty("Content-Type",
"application/x-www-form-urlencoded;charset=" + "UTF-8");
Uri.Builder builder = new Uri.Builder()
.appendQueryParameter("user", "1111")
.appendQueryParameter("pass", "1111");
String query = builder.build().getEncodedQuery();
OutputStream os = connection.getOutputStream();
BufferedWriter writer = new BufferedWriter(
new OutputStreamWriter(os, "UTF-8"));
writer.write(query);
writer.flush();
writer.close();
os.close();
InputStream is = connection.getInputStream();
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
StringBuffer response = new StringBuffer();
String line = "";
while((line = rd.readLine()) != null) {
response.append(line);
response.append('\r');
}
rd.close();
line = response.toString();
return line;
} catch (Exception e) {
Log.w("MyApp", "Download Exception : " + e.toString());
}
return null;
}
@Override
protected void onPostExecute(String result) {
if (result != null) {
}
}
I am observing this service from last 53 hours. Service is running fine (Settings>app>Running). I have tried different things to ensure the 24 hour connectivity of app which includes turning WiFi radio off and on, turning my WiFi router on and off, plugging out internet cable from router and then putting it back in. App was working fine. But after 28 hours when I checked my app, I found that app is not downloading data from internet. It seems that app was trying to connect with internet but after time out it downloaded nothing. I have checked the web page which app was trying to access via web browser of android device, it was running fine. I have turned wifi radio off and on and app immediately get connected with internet. Now what I can do to ensure that my app keeps it connection established with web server?
Update
AsyncTask download some information which is no more than 160 bytes in form of text. We have poultry business so this information contains new rates of local area.
App starts this service at regular intervals (15 sec) by scheduling task using AlaramManager class.
来源：https://stackoverflow.com/questions/31846657/24-hour-android-app-connection-with-php-web-server