android - 如何在后台服务中放置一个带有无限循环的线程

Question

我正在开发的应用程序将根据许愿者登记的生日日期和时间自动发送生日祝福。我已经创建了一个带有无限循环的线程，它将从数据库中获取今天日期的记录，以自动每分钟自动发送消息。

我的代码在正常 Activity 中正常运行。我想放在 SERVICE 中。所以请帮助我如何放置此代码并在应用程序启动时调用服务。

这是我的代码

// function to run thread
void startThread()
{
       Thread th=new Thread(){  
            @Override
            public void run(){  
                // 
               try
                {   
                    for (;;)
                    {
                                runOnUiThread(new Runnable() { 
                                @Override
                                public void run() {
                                    try {
                                        //Getting the system date                                       
                                        Calendar today=new GregorianCalendar();                   
                                        SimpleDateFormat simdate=new SimpleDateFormat("yyyy-MM-dd");                                            
                                        SimpleDateFormat timeFormat=new SimpleDateFormat("hh:mm a");                                    
                                        String systemDate=simdate.format(today.getTime());
                                        String systemTime=timeFormat.format(today.getTime());

                                        // system process

                                        minText.setText(systemTime);

                                        control.open();
                                        ArrayList<UserPOJO> event=control.MyDatabaseRecords(systemDate);//get the records for system date
                                        for(int i=0;i<event.size();i++)
                                        {
                                            String dbContactID=event.get(i).getContactID(); 
                                            String dbContactNumber=event.get(i).getContactNumber(); 
                                            String dbContactMessage=event.get(i).getContactMessageBody();   
                                            String dbDate=event.get(i).getContactWishDate();    
                                            String dbTime=event.get(i).getContactWishTime();    


                                            String[] time=dbTime.split("[ \\:]");
                                            String myhr=time[0];
                                            String mymin=time[1];
                                            String aorp=time[2];
                                            String myDBhr=addZeroBeforeDate(myhr);
                                                                 // adding zero before time hour
                                            String CurrentDBTime=myDBhr+":"+mymin+" "+aorp;



                                            Toast.makeText(getApplicationContext(),"Searching.....", 300).show();

                                            //Toast.makeText(getApplicationContext(),"DB Time:"+CurrentDBTime+"System Time"+systemTime, 300).show();


                                            if((dbDate.equals(systemDate))&& (CurrentDBTime.equals(systemTime)))
                                            {// 
                                                System.out.println("Message Send at:"+systemTime);
                                                Toast.makeText(getApplicationContext(),"Message Sent to :"+dbContactNumber+"on System time:"+systemTime, 300).show();
                                                 sendSMS(dbContactNumber, dbContactMessage);                

                                                //send.sendSMS(dbContactNumber, dbContactMessage);
                                            }
                                    }

                                    }
                                    catch(Exception e) 
                                    {
                                        e.printStackTrace();
                                    } 
                                }
                                });  
                                Thread.sleep(60000);
                               // Thread.sleep(20000);
                     // set the scan for 60 seconds
                    }
                }
                catch (InterruptedException e) {
                }

            }   // run
        };
    th.start();
}

   // Add zero if it is 

   dateval<10
   private static String addZeroBeforeDate(String datevalue)
   {
        String dval=datevalue;

        for(int i=dval.length();i<2;i++)
        {
            dval="0"+dval;
        }

        return dval;
   }

Answer 1

你应该使用 IntentService与 AlarmManager定期调用服务:

IntentService的onHandleIntent()方法是在不同线程调用的，不用担心会阻塞UI。

AlarmManager 也应该比 TimerTask 更高效。 (参见 Timer Task VS Alarm Manager usage in Android Service)

public class MyService extends IntentService {

    private AlarmManager alarmManager;

    private boolean started;
    private PendingIntent pendingIntent;

    public MyService() {
        super(MyService.class.getSimpleName());
    }

    @Override
    public void onCreate() {
        super.onCreate();
        alarmManager = (AlarmManager) getApplicationContext().getSystemService(Context.ALARM_SERVICE);
    }

    @Override
    protected void onHandleIntent(Intent intent) {
        if (! started) {
            started = true;

            // Call the service periodically every 15 minutes
            pendingIntent = PendingIntent.getService(
                    getApplicationContext(), 
                    0, 
                    intent, 
                    PendingIntent.FLAG_UPDATE_CURRENT);

            alarmManager.setRepeating(
                    AlarmManager.ELAPSED_REALTIME, 
                    AlarmManager.INTERVAL_FIFTEEN_MINUTES,
                    AlarmManager.INTERVAL_FIFTEEN_MINUTES,
                    pendingIntent);
        }

        // DO YOUR STUFF HERE
    }
}

看看 AlarmManager documention您可以使用的选项。