Building an Android Wear app

A brief talk about building an Android Wear app presented at one of our weekly tech talks.

Transcript

1. Building an Android Wear
   app
   

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2. Anatomy of an Android Wear app
   4 Wearable app
   4 Mobile app, with wearable app packaged inside
   4 Communicate via notifications and/or Google Play
   Services APIs
   

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3. Never Gonna GIF
   You Up
   

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4. Loading a random GIF on the watch
   1. UI library for displaying GIFs
   2. Request random GIF from Giphy API
   3. Make API request, update view
   

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5. Loading a random GIF on the watch
   1. UI library for displaying GIFs
   2. Request random GIF from Giphy API
   3. Make API request, update view
   Most wearables don't have internet...yet
   

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6. Wearable app
   

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7. Wearable app
   1. UI library for displaying GIFs
   2. Request GIF from mobile app
   3. Listen for data change from phone
   4. Update view
   

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8. Request GIF from mobile app
   Set nodes = Wearable.CapabilityApi
   .getCapability(googleApiClient, "gif_me",
   CapabilityApi.FILTER_REACHABLE)
   .await()
   .getCapability()
   .getNodes();
   if (!nodes.isEmpty()) {
   for (Node node : nodes) {
   Wearable.MessageApi.sendMessage(googleApiClient, node.getId(),
   "gif/random", null).await();
   }
   }
   

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9. Listen for data changes
   @Override
   public void onDataChanged(DataEventBuffer dataEvents) {
   for (DataEvent event : dataEvents) {
   if (event.getType() == DataEvent.TYPE_CHANGED) {
   DataItem item = event.getDataItem();
   if (item.getUri().getPath().compareTo("/image") == 0) {
   Asset asset =
   DataMapItem.fromDataItem(item).getDataMap().get("random_gif");
   // Do something with asset
   }
   }
   }
   }
   

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10. Mobile app
    

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11. Mobile app
    1. WearableListenerService to listen for GIF requests
    2. Request random GIF from Giphy API
    3. Push file bytes to wearable via Data API
    

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12. Registering a WearableListenerService
    - AndroidManifest.xml
    android:name=".GifRequestWearableListenerService"
    tools:ignore="ExportedService" >
    
    
    
    
    

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13. Registering a WearableListenerService:
    res/values/wear.xml
    
    
    gif_me
    
    
    

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14. WearableListenerService
    public class GifRequestWearableListenerService
    extends WearableListenerService {
    @Override
    public void onMessageReceived(MessageEvent messageEvent) {
    if (messageEvent.getPath().equals("gif/random")) {
    bytes[] imageBytes = getRandomGif();
    Asset asset = Asset.createFromBytes(imageBytes)
    pushAsset(asset);
    }
    }
    private void pushAsset(Asset asset) {
    PutDataMapRequest request = PutDataMapRequest.create("/image");
    request.getDataMap().putAsset("random_gif", asset);
    Wearable.DataApi.putDataItem(googleApiClient, request.asPutDataRequest());
    }
    }
    

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15. Achtung!
    4 Enable developer options and debugging on the
    wearable
    4 Packaged wearable apps aren't automatically
    deployed for debug builds
    4 Deploy the right app to the right device
    4 It's difficult to debug end-to-end. Focus on one end at
    a time.
    

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16. Weird stuff
    4 Retrolambda doesn't currently work with Android
    Wear. It seems to break the packaging of the
    wearable app into the mobile app.
    

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