許小美@Forgame.Taipei

Android的三鐵共構

Eventbus

Android Taipei - Dec 29 2014

Simple Example

1. Fragment Activity
2. Fragment
3. ListView
4. Handler
5. AsyncTask

Complex Example

1. Fragment Activity
2. Fragment
3. ListView
4. Handler
5. AsyncTask
6. Broadcast
7. Service
8. etc.

Complex Connect 

攏長的 Code 會讓人忘記哪條通道有在使用

就像是還有人認為忠孝西路有公車停靠一般...

為什麼不能簡單點呢！

Pretty Code...

What is Eventbus?

EventBus is publish/subscribe event bus optimized for Android.

Eventbus

Eventbus Component

• Publishers
• Subscribers
• Events
• Bus

EventBus in 4 Steps

• Define an event
  Public class MyEvent{}
• Register subscriber
  EventBus.getDefault().register(this);
• Post an event
  EventBus.getDefault().post(event);
• Receive the event
  Public void onEvent(MyEvent event);

Define an event

public class Event { 
  public static class ItemListEvent {  
    private List<Item> items;

    public ItemListEvent(List<Item> items) {  
      this.items = items;  
    }

    public List<Item> getItems() {  
      return items;  
    }
  }
}

register/unregister subscriber

@Override  
public void onCreate(Bundle savedInstanceState) {  
    super.onCreate(savedInstanceState);  
    // Register  
    EventBus.getDefault().register(this);  
}  
  
@Override  
public void onDestroy() {  
    super.onDestroy();  
    // Unregister  
    EventBus.getDefault().unregister(this);  
}  

Post an event

// Get listview items data from Network
EventBus.getDefault().post(new ItemListEvent(Item.ITEMS));

Receive the event

public void onEventMainThread(ItemListEvent event) {  
  setListAdapter(new ArrayAdapter<Item>(getActivity(),  
     android.R.layout.simple_list_item_activated_1,  
     android.R.id.text1, event.getItems()));  
}  

• onEventPostThread
• onEventMainThread
• onEventBackgroundThread
• onEventAsync

EventBus Thread Mode

Summary

• Easy use
• Pretty Code
• Observer Pattern
• Performs well with Activities, Fragment, Background threads