Android每X秒运行一次服务线程

Question

我想在每 X 秒运行一次的 Android 服务中创建一个线程

我目前正在使用，但 postdelayed 方法似乎真的落后于我的应用程序。

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

    super.onStartCommand(intent, flags, startId);

    startRepeatingTask();

    return startId;
}

private final static int INTERVAL = 20000; //20 milliseconds
Handler m_handler = new Handler();

Runnable m_handlerTask = new Runnable()
{
     @Override 
     public void run() {
         // this is bad
          m_handler.postDelayed(m_handlerTask, INTERVAL);
     }
};

void startRepeatingTask()
{
    m_handlerTask.run(); 
}

void stopRepeatingTask()
{
   m_handler.removeCallbacks(m_handlerTask);
   stopSelf();
}

我想做一个这样的新线程：

public void threadRun()
{
    Thread triggerService = new Thread(new Runnable(){
        public void run(){
            Looper.prepare();
            try{
                    //do stuff here?

            }catch(Exception ex){
                    System.out.println("Exception in triggerService Thread -- "+ex);
            }//end catch


        }//end run
    }, "aThread");
    triggerService.start();      

    //perhaps do stuff here with a timer?
    timer1=new Timer();

    timer1.scheduleAtFixedRate(new methodTODOSTUFF(), 0, INTERVAL);
}

我不确定让后台线程以特定间隔运行的最佳方法，感谢您的见解！

Answer 1

有许多替代方法可以做到这一点。就个人而言，我更喜欢使用ScheduledExecutorService：

ScheduledExecutorService scheduleTaskExecutor = Executors.newScheduledThreadPool(5);

// This schedule a runnable task every 2 minutes
scheduleTaskExecutor.scheduleAtFixedRate(new Runnable() {
  public void run() {
    doSomethingUseful();
  }
}, 0, 2, TimeUnit.MINUTES);

Answer 2

这是我运行重复线程的方式，您会看到它每 1 秒循环一次。我认为这种方法没有滞后。

final Thread t = new Thread(new RepeatingThread());
t.start();

还有班级：

import android.os.Handler;

public class RepeatingThread implements Runnable {

    private final Handler mHandler = new Handler();

    public RepeatingThread() {

    }

    @Override
    public void run() { 
        mHandler.postDelayed(this, 1000);       
    }
}

Answer 3

MyService.java

public class MyService extends Service {

    public static final int notify = 5000;  //interval between two services(Here Service run every 5 seconds)
    int count = 0;  //number of times service is display
    private Handler mHandler = new Handler();   //run on another Thread to avoid crash
    private Timer mTimer = null;    //timer handling

    @Override
    public IBinder onBind(Intent intent) {
        throw new UnsupportedOperationException("Not yet implemented");
    }

    @Override
    public void onCreate() {
        if (mTimer != null) // Cancel if already existed
            mTimer.cancel();
        else
            mTimer = new Timer();   //recreate new
        mTimer.scheduleAtFixedRate(new TimeDisplay(), 0, notify);   //Schedule task
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        mTimer.cancel();    //For Cancel Timer
        Toast.makeText(this, "Service is Destroyed", Toast.LENGTH_SHORT).show();
    }

    //class TimeDisplay for handling task
    class TimeDisplay extends TimerTask {
        @Override
        public void run() {
            // run on another thread
            mHandler.post(new Runnable() {
                @Override
                public void run() {
                    // display toast
                    Toast.makeText(MyService.this, "Service is running", Toast.LENGTH_SHORT).show();
                }
            });

        }

    }
}

MainActivity.java

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        startService(new Intent(this, MyService.class)); //start service which is MyService.java
    }
}

在AndroidManifest.xml中添加以下代码

AndroidManifest.xml

<service android:name=".MyService" android:enabled="true" android:exported="true"></service>

Answer 4

每隔几秒启动一个runnable 就会有一些延迟，不管你怎么切它，不是吗？我不明白为什么 Handler 不能正常工作。

你可能会遇到一些麻烦，因为你有

void startRepeatingTask()
{
    m_handlerTask.run(); 
}

相反，您应该使用处理程序并执行以下操作：

void startRepeatingTask()
{
    m_handler.post(m_handlerTask); 
}

（顺便说一句，Java 中的约定是使用驼峰式大小写，而不是蛇形大小写。所以它应该是 mHandler，而不是 m_handler 等。只是告诉你，因为它可能会让你的代码更容易阅读。）