Android的Java - 如何使活動等待，直到服務綁定？

Question

每個示例都有Service onStart（），並在一段時間內從Service調用方法（如onClick之後）。直到那個onClick服務被綁定。

我得到的問題，服務需要一段時間，直到它被綁定，它異步綁定。 因此，如果我啓動並且需要立即從服務獲取一些數據的活動 - 它會崩潰，因爲它尚未綁定。所以我需要等待我的活動​​等待連接完成。我怎麼做？

Answer 1

我想你想要的是：http://developer.android.com/guide/components/bound-services.html。

在此頁面，您可以找到：

/** Defines callbacks for service binding, passed to bindService() */ 
private ServiceConnection mConnection = new ServiceConnection() { 

    @Override 
    public void onServiceConnected(ComponentName className, 
      IBinder service) { 
     // We've bound to LocalService, cast the IBinder and get LocalService instance 
     LocalBinder binder = (LocalBinder) service; 
     mService = binder.getService(); 
     mBound = true; 
    } 

    @Override 
    public void onServiceDisconnected(ComponentName arg0) { 
     mBound = false; 
    } 
}; 

的onServiceConnected方法被調用時，該服務已準備就緒，你可以做你的東西里（或使用mBound屬性）。

要綁定到你的服務，使用：

// Bind to LocalService 
    Intent intent = new Intent(this, LocalService.class); 
    bindService(intent, mConnection, Context.BIND_AUTO_CREATE); 

Answer 2

您可以利用一個pendingList變量來處理這種情況：

private ICoreService mService; 
private boolean mConnected = false; 
private boolean mConnecting = false; 
private List<Something> mPendingTasks = new ArrayList<Something>; 

private void bindService() {  
     try { 
      Intent service = new Intent(); 
      service.setClassName(Constants.THE_SERVICE_PACKAGE_NAME, Constants.THE_SERVICE_FULL_NAME); 
      mContext.bindService(service, mServiceConnection, Context.BIND_AUTO_CREATE); 
      mConnecting = true; 
     } catch (Exception e) { 
       //handle exception 
     }   
} 

public void serviceDoSomething(Something task) { 
    try { 
     if (mService == null) { 
      synchronized (mPendingTasks) { 
       mPendingTasks.add(task); 
      } 
     } else { 
      mService.doSomething(task); 
     } 
    } catch (Exception e) { 
     //handle exception 
    } 
} 

private ServiceConnection mServiceConnection = new ServiceConnection() { 

    @Override 
    public void onServiceDisconnected(ComponentName name) { 
     mConnected = false; 
     mConnecting = false; 
     mService = null; 
    } 

    @Override 
    public void onServiceConnected(ComponentName name, IBinder service) { 
     mConnected = true; 
     mConnecting = false; 
     mService = ICoreService.Stub.asInterface(service); 
     drainPendingTasks(); 
    } 
}; 

private void drainPendingTasks() { 
    new Thread(new Runnable() { 
     @Override 
     public void run() { 
      synchronized (mPendingTasks) { 
       try { 
        if (!mPendingTasks.isEmpty()) { 
         for (Something task : mPendingTasks) { 
          mService.doSomething(task); 
         } 
         mPendingTasks.clear(); 
        } 
       } catch (Exception e) { 
        //handle exception 
       } 
      } 
     } 
    }).start(); 
}