java 在android中创建一个定时服务

Create a Scheduled service in android

提问by El Sa7eR

I need to create a schedule service in android with java. I have tried some codes , but all time after build the application it doesn't run. My logic is simple , I want to make a service to check the existence of a file in the bluetooth folder path, If this file is there , so this service will run another application , I need this with a schedule which run every 2 minutes.

我需要在 android 中用 java 创建一个调度服务。我已经尝试了一些代码，但在构建应用程序后一直没有运行。我的逻辑很简单，我想做一个服务来检查蓝牙文件夹路径中的文件是否存在，如果这个文件在那里，那么这个服务将运行另一个应用程序，我需要这个计划，每 2 分钟运行一次。

Until now that's great, but now I have an error The method startActivity(Intent) is undefined for the type MyTimerTask. I have tried this code...

到目前为止，这很好，但现在我有一个错误The method startActivity(Intent) is undefined for the type MyTimerTask。我试过这个代码...

public class MyTimerTask extends TimerTask {
    java.io.File file = new java.io.File("/mnt/sdcard/Bluetooth/1.txt");

    public void run(){ 
        if (file.exists()) {
            Intent intent = new Intent(Intent.ACTION_MAIN);
            intent.setComponent(new ComponentName("com.package.address","com.package.address.MainActivity"));
            startActivity(intent);
        }
    } 
}

Could someone please help me with this.

有人可以帮我解决这个问题。

回答by Lucifer

There are two ways to achieve your requirement.

有两种方法可以实现您的要求。

• TimerTask

• Alarm Manager Class

  TimerTask has a method that repeats the activity on the given particular time interval. look at the following sample example.

  Timer timer; 
  MyTimerTask timerTask; 
  
  timer = new Timer(); 
  timerTask = new MyTimerTask();
  timer.schedule ( timerTask, startingInterval, repeatingInterval );
  
  private class MyTimerTask extends TimerTask 
  {
       public void run()
       { 
          ...
          // Repetitive Activity goes here
       } 
  }
  

  AlarmManagerdoes same thing like TimerTaskbut as it occupies lesser memory to execute tasks.

  public class AlarmReceiver extends BroadcastReceiver 
  {
      @Override
      public void onReceive(Context context, Intent intent) 
      {
          try 
          {
              Bundle bundle = intent.getExtras();
              String message = bundle.getString("alarm_message");
              Toast.makeText(context, message, Toast.LENGTH_SHORT).show();
          } 
          catch (Exception e) 
          {
               Toast.makeText(context, "There was an error somewhere, but we still received an alarm", Toast.LENGTH_SHORT).show();
   e.printStackTrace();
          }
     }
  }
  

• 定时器任务

• 报警管理器类

  TimerTask 有一个方法可以在给定的特定时间间隔内重复活动。请看以下示例。

  Timer timer; 
  MyTimerTask timerTask; 
  
  timer = new Timer(); 
  timerTask = new MyTimerTask();
  timer.schedule ( timerTask, startingInterval, repeatingInterval );
  
  private class MyTimerTask extends TimerTask 
  {
       public void run()
       { 
          ...
          // Repetitive Activity goes here
       } 
  }
  

  AlarmManager做同样的事情，TimerTask但因为它占用较少的内存来执行任务。

  public class AlarmReceiver extends BroadcastReceiver 
  {
      @Override
      public void onReceive(Context context, Intent intent) 
      {
          try 
          {
              Bundle bundle = intent.getExtras();
              String message = bundle.getString("alarm_message");
              Toast.makeText(context, message, Toast.LENGTH_SHORT).show();
          } 
          catch (Exception e) 
          {
               Toast.makeText(context, "There was an error somewhere, but we still received an alarm", Toast.LENGTH_SHORT).show();
   e.printStackTrace();
          }
     }
  }
  

AlarmClass,

报警类，

private static Intent alarmIntent = null;
private static PendingIntent pendingIntent = null;
private static AlarmManager alarmManager = null;

    // OnCreate()
    alarmIntent = new Intent ( null, AlarmReceiver.class );
    pendingIntent = PendingIntent.getBroadcast( this.getApplicationContext(), 234324243, alarmIntent, 0 );
alarmManager = ( AlarmManager ) getSystemService( ALARM_SERVICE );
    alarmManager.setRepeating( AlarmManager.RTC_WAKEUP, ( uploadInterval * 1000 ),( uploadInterval * 1000 ), pendingIntent );