我尝试了以下代码为 
 Android通知,这是正常工作,但它是在我启动我的Android应用程序时给我通知弹出窗口. 
  
  
 
I want to show an notification after every 48hours,how can I do it?
为了实现这一点,我需要做出哪些改变?
通知代码
Intent notificationIntent = new Intent(MainActivity.this,Activity.class);
        PendingIntent contentIntent = PendingIntent.getActivity(MainActivity.this,notificationIntent,0);
         notificationmanager notificationmanager = (notificationmanager) MainActivity.this
                    .getSystemService(Context.NOTIFICATION_SERVICE);
         Notification noti = new NotificationCompat.Builder(MainActivity.this)
                            .setSmallIcon(R.drawable.ic_launcher)
                            .setTicker("ticker message")
                            .setWhen(System.currentTimeMillis())
                            .setContentTitle("HELLO")
                            .setContentText("PLEASE CHECK WE HAVE UPDATED NEWS")
                            .setContentIntent(contentIntent)
                            //At most three action buttons can be added
                            .setAutoCancel(true).build();
        int notifyID =0;
        notificationmanager.notify(notifyID,noti);
解决方法
 这是您在主要活动中所需要的东西: 
  
  
 
        Intent notificationIntent = new Intent(context,ShowNotification.class);
    PendingIntent contentIntent = PendingIntent.getService(context,PendingIntent.FLAG_CANCEL_CURRENT);
    AlarmManager am = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
    am.cancel(contentIntent);
    am.setRepeating(AlarmManager.RTC_WAKEUP,System.currentTimeMillis()
            + AlarmManager.INTERVAL_DAY * 2,AlarmManager.INTERVAL_DAY * 2,contentIntent); 
 然后,在另一个名为ShowNotification.java的文件中,添加以下内容(假设您的主要活动名为MainActivity):
import android.app.Notification;
import android.app.notificationmanager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.os.IBinder;
import android.support.v4.app.NotificationCompat;
import android.util.Log;
public class ShowNotification extends Service {
    private final static String TAG = "ShowNotification";
    @Override
    public void onCreate() {
        super.onCreate();
        Intent mainIntent = new Intent(this,MainActivity.class);
        notificationmanager notificationmanager
            = (notificationmanager) this.getSystemService(Context.NOTIFICATION_SERVICE);
        Notification noti = new NotificationCompat.Builder(this)
            .setAutoCancel(true)
            .setContentIntent(PendingIntent.getActivity(this,mainIntent,PendingIntent.FLAG_UPDATE_CURRENT))
            .setContentTitle("HELLO " + System.currentTimeMillis())
            .setContentText("PLEASE CHECK WE HAVE UPDATED NEWS")
            .setDefaults(Notification.DEFAULT_ALL)
            .setSmallIcon(R.drawable.ic_launcher)
            .setTicker("ticker message")
            .setWhen(System.currentTimeMillis())
            .build();
        notificationmanager.notify(0,noti);
        Log.i(TAG,"Notification created");
    }
    @Override
    public IBinder onBind(Intent intent) {
        // Todo Auto-generated method stub
        return null;
    }
}