如何在Android的後臺訪問數據庫？

Question

我正在研究一個應用程序，其中某些任務可以由用戶在db中創建。我想設置警報管理器按用戶設置的時間執行任務，但與我的主要問題是，我沒有得到如何爲數據庫中創建的所有任務設置警報管理器或爲多個任務設置警報管理器。請建議我如何滿足我的要求。

Answer 1

木箱不同的定時器任務，按時間，你需要

CountDownTimer vanishTimer = new CountDownTimer(Timer, tick) { 

     @Override 
     public void onTick(long millisUntilFinished) { 



     } 

     @Override 
     public void onFinish() { 
      // TODO Auto-generated method stub 
      //your Db operations 


     } 
    }; 

Answer 2

this way you can use this as u want to get data from sqlite database 

package com.location.zealalerts; 

import java.util.ArrayList; 
import java.util.Calendar; 
import java.util.Timer; 
import java.util.TimerTask; 
import java.util.regex.Pattern; 

import android.accounts.Account; 
import android.accounts.AccountManager; 
import android.app.Service; 
import android.content.Context; 
import android.content.Intent; 
import android.database.Cursor; 
import android.location.Criteria; 
import android.location.Location; 
import android.location.LocationManager; 
import android.os.IBinder; 
import android.telephony.gsm.SmsManager; 
import android.util.Log; 
import android.util.Patterns; 

@SuppressWarnings("deprecation") 
public class LocationService extends Service { 


    Calendar c; 
    int mYear, mMonth, mDay, mHour, mMin, mSec; 

    ArrayList<String> Tasks = new ArrayList<String>(); 
    ArrayList<String> Desc = new ArrayList<String>(); 
    ArrayList<String> Task_date = new ArrayList<String>(); 
    ArrayList<String> Start_Time = new ArrayList<String>(); 
    ArrayList<String> Priority = new ArrayList<String>(); 

    ArrayList<Double> lat_array = new ArrayList<Double>(); 
    ArrayList<Double> long_array = new ArrayList<Double>(); 
    ArrayList<Double> radius_array = new ArrayList<Double>(); 

    ArrayList<Integer> ids = new ArrayList<Integer>(); 

    ArrayList<Integer> alertid = new ArrayList<Integer>(); 
    ArrayList<String> type = new ArrayList<String>(); 
    ArrayList<String> phone_email = new ArrayList<String>(); 
    ArrayList<String> content = new ArrayList<String>(); 

    ArrayList<String> temp_Tasks = new ArrayList<String>(); 
    boolean isOutside[]; 

    DBAdapter mDbAdapter; 
    double distance; 
    double longitude,latitude; 
    String to; 
    String txt_msg; 
    @Override 
    public void onCreate() { 
     Log.i("Background service ", "calls"); 


     recurscall_time_alert(); 

    } 




    public static double distFrom(double lat1, double lng1, double lat2, 
      double lng2) { 
     double earthRadius = 3958.75; 
     double dLat = Math.toRadians(lat2 - lat1); 
     double dLng = Math.toRadians(lng2 - lng1); 
     double sindLat = Math.sin(dLat/2); 
     double sindLng = Math.sin(dLng/2); 
     double a = Math.pow(sindLat, 2) + Math.pow(sindLng, 2) 
       * Math.cos(Math.toRadians(lat1)) 
       * Math.cos(Math.toRadians(lat2)); 
     double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a)); 
     double dist = earthRadius * c; 

     return dist; 
    } 

    private void recurscall_time_alert() { 
     // TODO Auto-generated method stub 
     new Timer().scheduleAtFixedRate(new TimerTask() { 

      @SuppressWarnings("deprecation") 
      @Override 
      public void run() { 


       get_latlong(); 

       get_contacts(); 
       Log.d("Time Alert", "Call Time Alert"); 


      } 
     }, 7*1000, 180 * 1000); 

    } 



    void get_latlong() { 

     mDbAdapter = new DBAdapter(getApplicationContext()); 
     mDbAdapter.read_open(); 

     Cursor cr = mDbAdapter.fetchAllTasks(); 
     cr.moveToFirst(); 
     ids.clear(); 
     Tasks.clear(); 
     Priority.clear(); 
     lat_array.clear(); 
     long_array.clear(); 
     radius_array.clear(); 
     Start_Time.clear(); 
     Task_date.clear(); 
     Desc.clear(); 
     while (!cr.isAfterLast()) { 

      ids.add(Integer.parseInt(cr.getString(0))); 
      Tasks.add(cr.getString(1)); 
      Priority.add(cr.getString(2)); 
      Task_date.add(cr.getString(3)); 
      Start_Time.add(cr.getString(5)); 
      lat_array.add(Double.valueOf(cr.getString(6))); 
      long_array.add(Double.valueOf(cr.getString(7))); 
      radius_array.add(Double.parseDouble(cr.getString(8))); 
      cr.moveToNext(); 

     } 
     cr.close(); 

     mDbAdapter.close(); 
     Log.d("LatLongs::", "Lattitude:" + String.valueOf(lat_array) 
       + "long_array:" + String.valueOf(long_array)); 

     //get_contacts(); 

    } 

    public void get_contacts() { 
     mDbAdapter = new DBAdapter(getApplicationContext()); 
     mDbAdapter.read_open(); 
     Cursor cr2 = mDbAdapter.fetchAllTaskContacts(); 
     cr2.moveToFirst(); 
     alertid.clear(); 
     phone_email.clear(); 
     type.clear(); 
     content.clear(); 

     while (!cr2.isAfterLast()) { 

      alertid.add(Integer.parseInt(cr2.getString(0))); 
      phone_email.add(cr2.getString(2)); 
      type.add(cr2.getString(3)); 
      content.add(cr2.getString(4)); 
      cr2.moveToNext(); 

     } 
     cr2.close(); 
     mDbAdapter.close(); 
     Log.d("Contacts", String.valueOf(alertid) + phone_email + type 
       + content); 

    } 

    @Override 
    public IBinder onBind(Intent intent) { 
     return null; 
    } 


}