长寿服务和广播接收器

Question

我编写的应用程序将来自android的拨出电话号码发送到服务器。

这是我的代码：

service.java

package info;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;


public class ServiceToSendData extends Service {

    //    private static final String TAG       = "HelloService";
    public static boolean isRunning = false;


    @Override
    public IBinder onBind(Intent arg0) {
        return null;
    }


    @Override
    public void onCreate() {
        isRunning = true;

    }


    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        new Thread(new Runnable() {

            @Override
            public void run() {

            }
        }).start();
        return Service.START_STICKY;
    }


    @Override
    public void onDestroy() {
        isRunning = false;
    }

}

outgoingCall Reciver

import org.json.JSONException;
import org.json.JSONObject;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.os.StrictMode;


public class OutgoingCallReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();

        StrictMode.setThreadPolicy(policy);
        String phoneNumber = intent.getStringExtra(Intent.EXTRA_PHONE_NUMBER);
        //        Log.i("Outgoing Call", "call to: " + phoneNumber);

        JSONObject jsonObject = new JSONObject();
        try {
            jsonObject.put("type", "outgoingCall");
        }
        catch (JSONException e) {
            e.printStackTrace();
        }
        try {
            jsonObject.put("number", phoneNumber);
        }
        catch (JSONException e) {
            e.printStackTrace();
        }
        try {
            jsonObject.put("content", "0");
        }
        catch (JSONException e) {
            e.printStackTrace();
        }

        if (phoneNumber != null) {
            sendDataToServer sdts = new sendDataToServer();
            sdts.run(jsonObject, context);
        }
        Intent startServiceIntent = new Intent(context, ServiceToSendData.class);
        context.startService(startServiceIntent);

    }
}

解释问题

1 - 如果应用程序处于打开状态或应用程序已最小化，此代码可以正常工作，但是当我关闭应用程序代码无效时，以及nullpointerexception问题？

2 - 从服务中使用上下文访问数据库的任何方式吗？

提前感谢。