Android中的優先隊列服務

Question

我想實現一個基於簡單數字優先級處理意圖的IntentService（source code）。具有較高優先級的意圖應該首先由服務處理，而不是具有較低優先級的意向。

Android上有什麼東西可以做到這一點嗎？如果沒有，關於如何實現它的任何指針？

Answer 1

基於CommonsWare的答案和Android的IntentServicesource code第一次嘗試實施具有優先級的意圖服務。將進行廣泛測試並進行相應的編輯。

public abstract class PriorityIntentService extends Service { 

    private final class QueueItem implements Comparable<QueueItem> { 
     Intent intent; 
     int priority; 
     int startId; 

     @Override 
     public int compareTo(QueueItem another) { 
      if (this.priority < another.priority) { 
       return -1; 
      } else if (this.priority > another.priority) { 
       return 1; 
      } else { 
       return (this.startId < another.startId) ? -1 : 1; 
      } 
     } 
    } 
    private final class ServiceHandler extends Handler { 
     public ServiceHandler(Looper looper) { 
      super(looper); 
     } 

     @Override 
     public void handleMessage(Message msg) { 
      try { 
       final QueueItem item = mQueue.take(); 
       onHandleIntent(item.intent); 
       if (mQueue.isEmpty()) { 
        PriorityIntentService.this.stopSelf(); 
       } 
      } catch (InterruptedException e) { 
       e.printStackTrace(); 
      } 
     } 
    } 
    public static final String EXTRA_PRIORITY = "priority"; 
    private String mName; 
    private PriorityBlockingQueue<QueueItem> mQueue; 
    private boolean mRedelivery; 
    private volatile ServiceHandler mServiceHandler; 
    private volatile Looper mServiceLooper; 

    public PriorityIntentService(String name) { 
     super(); 
     mName = name; 
    } 

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

    @Override 
    public void onCreate() { 
     super.onCreate(); 
     HandlerThread thread = new HandlerThread("PriorityIntentService[" + mName + "]"); 
     thread.start(); 

     mServiceLooper = thread.getLooper(); 
     mServiceHandler = new ServiceHandler(mServiceLooper); 
     mQueue = new PriorityBlockingQueue<QueueItem>(); 
    } 

    @Override 
    public void onDestroy() { 
     mServiceLooper.quit(); 
    } 

    protected abstract void onHandleIntent(Intent intent); 

    @Override 
    public void onStart(Intent intent, int startId) { 
     final QueueItem item = new QueueItem(); 
     item.intent = intent; 
     item.startId = startId; 
     final int priority = intent.getIntExtra(EXTRA_PRIORITY, 0); 
     item.priority = priority; 
     mQueue.add(item); 
     mServiceHandler.sendEmptyMessage(0); 
    } 

    @Override 
    public int onStartCommand(Intent intent, int flags, int startId) { 
     onStart(intent, startId); 
     return mRedelivery ? START_REDELIVER_INTENT : START_NOT_STICKY; 
    } 

    public void setIntentRedelivery(boolean enabled) { 
     mRedelivery = enabled; 
    } 
} 

Answer 2

不是。雖然沒有太多的IntentService。在PriorityBlockingQueue的支持下烹飪PriorityIntentService，而不是Handler + Looper，應該不會太長。