目前,我的應用程序需要做的每5秒一個的任務,這涉及到更新標記的位置在谷歌地圖API的使用地圖。但是,只有當應用程序打開並且人們正在使用它時,才需要每5秒鐘完成一次。僅當應用程序打開時,我如何每隔幾秒就運行一次Android代碼?
看來的AsyncTask,根據人在互聯網上,甚至當應用程序被關閉,導致它使用了大量的電池壽命運行。
如何讓這個任務運行,當且僅當應用程序是打開還是剛剛開始?
private class MyAsyncTask extends AsyncTask<String, String, Void> {
InputStream inputStream = null;
String result = "";
@Override
protected Void doInBackground(String... params) {
String url_select = "https://www.example.com/"; // generic
try {
URL url = new URL(url_select);
HttpURLConnection connectTo = (HttpURLConnection) url.openConnection();
connectTo.setRequestProperty("User-Agent", "");
connectTo.setRequestMethod("POST");
connectTo.setDoInput(true);
connectTo.connect();
// Read content & Log
inputStream = connectTo.getInputStream();
} catch (IOException e4) {
Log.e("IOException", e4.toString());
e4.printStackTrace();
}
// Convert response to string using String Builder
try {
BufferedReader bReader = new BufferedReader(new InputStreamReader(inputStream, "utf-8"), 8);
StringBuilder sBuilder = new StringBuilder();
String line = null;
while ((line = bReader.readLine()) != null) {
sBuilder.append(line + "\n");
}
inputStream.close();
result = sBuilder.toString();
} catch (Exception e) {
Log.e("St.Build,BuffRead", "Error converting result " + e.toString());
}
return null;
} // protected Void doInBackground(String... params)
@Override
protected void onPostExecute(Void v) {
//parse JSON data
try {
JSONObject busData = new JSONObject(result);
if (busData.getString("title").equals("Bus Positions")) {
for (Marker mark: allBuses) {
mark.remove(); // Remove marker
}
allBuses.clear();
JSONObject resultSet = busData.getJSONObject("ResultSet");
JSONArray results = resultSet.getJSONArray("Result");
for (int i = 0; i < results.length(); i++) {
JSONObject bus = results.getJSONObject(i);
double lat = bus.getDouble("lat");
double lng = bus.getDouble("lng");
int call_name = bus.getInt("call_name");
String bus_type = "bus";
LatLng busLocation = new LatLng(lat,lng);
Marker busMark = map.addMarker(new MarkerOptions()
.position(busLocation)
.title(bus_type)
.icon(BitmapDescriptorFactory.fromResource(R.id.action_search)));
allBuses.add(busMark);
}
}
} catch (JSONException e) {
Log.e("JSONException", "Error: " + e.toString());
} // catch (JSONException e)
} // protected void onPostExecute(Void v)
}