從隊列中更新活動的最佳方法

Question

我在調製器中使用我的「Producer-Mediator-Consumer」模型中有一個LinkedBlockingQueue。生產者首先更新添加到activityQueue中的Mediator。接下來，消費者/活動在隊列上等待/收聽並抓取下一個項目。

我想要一個活動來查看隊列大小已更改，並抓住下一個項目。 調解員無法看到活動只有活動可以看到調解員。那麼，如何創建我想要的偵聽器機制？

這裏是我的調解器類，它包含隊列，活動將以某種方式查看隊列並獲知是否需要更新。進入隊列中的數據可能有點雜亂，因此輪詢機制無法工作。

public class MediatorData { 

    /** Queue for the Activity */ 
    LinkedBlockingQueue <byte[]> queueConsumer = new LinkedBlockingQueue <byte[]>(); 

    /** 
    * Add data to a queue(s) for consumption 
    */ 
    public void put(byte[] data) throws InterruptedException { 
     queueConsumer.add(data); 
    } 

    /** 
    * Return data from the queue for the Feature calculations 
    */ 
    public byte[] getFeatureData() throws InterruptedException { 
     return queueConsumer.poll(100, TimeUnit.MILLISECONDS); 
    } 

} 

我的活動類的示例，它的圖形類，因此隊列偵聽器必須高效快速。

public class DisplayGraph extends Activity { 

    // populated from Application Class where its created 
    pirvate MediatorData md; 

    public void onCreate(Bundle savedInstanceState) { 
     md = getMediator(); // This comes from the custom Application class 

     ... some type of listener to queue 
    } 

    private void getQueueData() { 
     byte[] tv = md.queueConsumer.poll(); 
     // can't update textview get exception CalledFromWrongThreadException 
     ((TextView) DisplayGraph.this.findViewById(R.id.tv)).setText("TV " + tv[0]); 
    } 
} 

Answer 1

最好的辦法是做到這一點：以前的答案中有錯誤。

public class MediatorData extends Observable { 

    /** Queue for the Activity */ 
    LinkedBlockingQueue <byte[]> queueConsumer = new LinkedBlockingQueue <byte[]>(); 

    /** 
    * Add data to a queue(s) for consumption 
    */ 
    public void put(byte[] data) throws InterruptedException { 
     queueConsumer.add(data); 
     notifyObservers(); 
    } 

    /** 
    * Return data from the queue for the Feature calculations 
    */ 
    public byte[] getFeatureData() throws InterruptedException { 
     return queueConsumer.poll(100, TimeUnit.MILLISECONDS); 
    } 
} 

顯示活動需要在UI線程上運行更新線程，因此請使用runOnUiThread方法。

public class DisplayGraph extends Activity implements Observer { 

    // populated from Application Class where its created 
    private MediatorData md; 

    byte[] tv; 

    public void onCreate(Bundle savedInstanceState) { 
     md = getMediator(); // This comes from the custom Application class 
     md.addObserver(this); 
    } 

    private void getQueueData() { 
     tv = md.queueConsumer.poll(); 
     runOnUiThread(setRunnable); 
    } 

    public void update(Observable arg0, Object arg1) { 
     getQueueData(); 
    } 

    // Need to do this to update the data to the UI. 
    final Runnable setImageRunnable = new Runnable() { 
     public void run() { 
      ((TextView) DisplayGraph.this.findViewById(R.id.tv)).setText("TV " + tv[0]); 
     } 
    }; 
} 

Answer 2

如何使用Observer和Observable？

可能是這樣的：

public class MediatorData extends Observable { 

    /** Queue for the Activity */ 
    LinkedBlockingQueue <byte[]> queueConsumer = new LinkedBlockingQueue <byte[]>(); 

    /** 
    * Add data to a queue(s) for consumption 
    */ 
    public void put(byte[] data) throws InterruptedException { 
     queueConsumer.add(data); 
     setChanged(); 
     notifyObservers(); 
    } 

    /** 
    * Return data from the queue for the Feature calculations 
    */ 
    public byte[] getFeatureData() throws InterruptedException { 
     return queueConsumer.poll(100, TimeUnit.MILLISECONDS); 
    } 
} 

這：處理這種情況

public class DisplayGraph extends Activity implements Observer { 

    // populated from Application Class where its created 
    private MediatorData md; 

    public void onCreate(Bundle savedInstanceState) { 
     md = getMediator(); // This comes from the custom Application class 
     md.addObserver(this); 
    } 

    private void getQueueData() { 
     byte[] tv = md.queueConsumer.poll(); 
     // can't update textview get exception CalledFromWrongThreadException 
     ((TextView) DisplayGraph.this.findViewById(R.id.tv)).setText("TV " + tv[0]); 
    } 

    public void update(Observable arg0, Object arg1) { 
     getQueueData(); 
    } 
}