Post on 18-Jul-2015
transcript
My way to clean Android v2
Christian Panadero
http://panavtec.me @PaNaVTEC
Github - PaNaVTEC
My Way to clean Android V2
My way to clean Android v2
Acknowledgements
Fernando Cejas
Jorge Barroso
Pedro Gomez
Sergio Rodrigo
@fernando_cejas
@flipper83
@pedro_g_s
@srodrigoDev
Android developer @ Sound CloudAndroid developer @ Karumi
Cofounder & Android expert @ Karumi
Android developer @ Develapps
Alberto Moraga
Carlos Morera
@albertomoraga
@CarlosMChica
iOS Developer @ Selltag
Android Developer @ Viagogo
My way to clean Android v2
• Independent of Frameworks
• Testable
• Independent of UI
• Independent of Database
• Independent of any external agency
Why clean architecture?
My way to clean Android v2
• Command pattern (Invoker, command, receiver)
• Decorator Pattern
• Interactors / Use cases
• Abstractions
• Data Source
• Repository
• Annotation Processor
Concepts
My way to clean Android v2
Abstraction levels
Presenters
Interactors
Entities
Repository
Data sources
UI
Abstractions
My way to clean Android v2
The dependency rule
Presenters
Interactors
Entities
Repository
Data sources
UI
Abstractions
My way to clean Android v2
• App (UI, DI and implementation details)
• Presentation
• Domain y Entities
• Repository
• Data Sources
Thinking in projects
My way to clean Android v2
Flow
View
Presenter
Presenter
Interactor
Interactor
Interactor
Interactor
Repository
Repository
DataSource
DataSource
DataSource
My way to clean Android v2
UI: MVPViewPresenter(s)
Model
Events
Fill the view
Actions Actions output
My way to clean Android v2
UI: MVP - Viewpublic class MainActivity extends BaseActivity implements MainView { @Inject MainPresenter presenter;
@Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); presenter.attachView(this); } @Override protected void onResume() { super.onResume(); presenter.onResume(); } @Override public void onRefresh() { presenter.onRefresh(); } }
My way to clean Android v2
UI: MVP - Presenterpublic class MainPresenter extends Presenter<MainView> {
public void onResume() { refreshContactList(); } public void onRefresh() { getView().refreshUi(); refreshContactList(); }
}
My way to clean Android v2
UI: MVP - Presenter
@ThreadDecoratedViewpublic interface MainView extends PresenterView { void showGetContactsError(); void refreshContactsList(List<PresentationContact> contacts); void refreshUi(); }
public interface PresenterView { void initUi(); }
prevents spoiler :D
My way to clean Android v2
• The configuration change is located in UI module, so solve it in this module
• configurationChange create a new Activity instance
• onRetainCustomNonConfigurationInstance to the rescue!
• Retain the DI graph
onConfigurationChange Hell
My way to clean Android v2
onConfigurationChange Hellpublic abstract class BaseActivity extends ActionBarActivity {
@Override protected void onCreate(Bundle savedInstanceState) { createActivityModule(); } private void createActivityModule() { activityInjector = (ActivityInjector) getLastCustomNonConfigurationInstance(); if (activityInjector == null) { activityInjector = new ActivityInjector(); activityInjector.createGraph(this, newDiModule()); } activityInjector.inject(this); } @Override public Object onRetainCustomNonConfigurationInstance() { return activityInjector; } protected abstract Object newDiModule(); }
My way to clean Android v2
Presentation - Domain (ASYNC)
Presenter Invoker
InteractorOutput
Invoker IMP
Interactor
My way to clean Android v2
Presentation - Domain (SYNC)
Presenter Invoker
Future
Invoker IMP
Interactor
.get();.cancel();
My way to clean Android v2
Presentation - Domainpublic class MainPresenter extends Presenter<MainView> { @Output InteractorOutput<List<Contact>, RetrieveContactsException> output;
public MainPresenter(…) { InteractorOutputInjector.inject(this); }
public void onResume() { interactorInvoker.execute(getContactsInteractor, output); }
@OnError void onContactsInteractorError(RetrieveContactsException data) { getView().showGetContactsError(); }
@OnResult void onContactsInteractor(List<Contact> result) { List<PresentationContact> presentationContacts = listMapper.modelToData(result); getView().refreshContactsList(presentationContacts); }
}
My way to clean Android v2
Domain - Interactorpublic class GetContactInteractor implements Interactor<Contact, ObtainContactException> { private ContactsRepository repository; private String contactMd5; public GetContactInteractor(ContactsRepository repository) { this.repository = repository; } public void setData(String contactMd5) { this.contactMd5 = contactMd5; } @Override public Contact call() throws ObtainContactException { return repository.obtain(contactMd5); } }
My way to clean Android v2
Bye bye thread Hell!
public class DecoratedMainView implements MainView {
@Override public void showGetContactsError() { this.threadSpec.execute(new Runnable() { @Override public void run() { undecoratedView.showGetContactsError(); } }); }
}
My way to clean Android v2
Bye bye thread Hell!public abstract class Presenter<V extends PresenterView> { private V view; private ThreadSpec mainThreadSpec; public Presenter(ThreadSpec mainThreadSpec) { this.mainThreadSpec = mainThreadSpec; } public void attachView(V view) { this.view = ViewInjector.inject(view, mainThreadSpec); } public void detachView() { view = null; } public V getView() { return view; } }
My way to clean Android v2
Bye bye thread Hell!
public class MainThreadSpec implements ThreadSpec { Handler handler = new Handler(); @Override public void execute(Runnable action) { handler.post(action); } }
public abstract class Presenter<V extends PresenterView> { public void attachView(V view) { this.view = ViewInjector.inject(view, mainThreadSpec); }
}
@ThreadDecoratedViewpublic interface MainView extends PresenterView { … }
My way to clean Android v2
Repository Interface
public interface ContactsRepository { List<Contact> obtainContacts() throws RetrieveContactsException; Contact obtain(String md5) throws ObtainContactException; }
My way to clean Android v2
Repository imp@Override public List<Contact> obtainContacts() throws RetrieveContactsException { List<Contact> contacts = null; try { contacts = bddDataSource.obtainContacts(); } catch (ObtainContactsBddException … ce) { try { contacts = networkDataSource.obtainContacts(); bddDataSource.persist(contacts); } catch (UnknownObtainContactsException … ue) { throw new RetrieveContactsException(); } catch (PersistContactsBddException … pe) { pe.printStackTrace(); } } return contacts; }
My way to clean Android v2
Data source Interface
public interface ContactsNetworkDataSource { public List<Contact> obtainContacts() throws ContactsNetworkException …; }
My way to clean Android v2
Data source impprivate ContactsApiService apiService; private static final Transformer transformer = new Transformer.Builder().build(ApiContact.class);
@Override public List<Contact> obtainContacts() throws ContactsNetworkException { try { ApiContactsResponse response = apiService.obtainUsers(100); List<ApiContactResult> results = response.getResults(); List<Contact> contacts = new ArrayList<>(); for (ApiContactResult apiContact : results) { contacts.add(transform(apiContact.getUser(), Contact.class)); } return contacts; } catch (Throwable e) { throw new ContactsNetworkException(); } }
My way to clean Android v2
Caching Strategypublic interface CachingStrategy<T> { boolean isValid(T data); }
public class TtlCachingStrategy<T extends TtlCachingObject> implements CachingStrategy<T> { private final long ttlMillis; @Override public boolean isValid(T data) { return (data.getPersistedTime() + ttlMillis) > System.currentTimeMillis(); } }
My way to clean Android v2
Caching Strategy@Override public List<Contact> obtainContacts() throws ObtainContactsBddException … { try { List<BddContact> bddContacts = daoContacts.queryForAll(); if (!cachingStrategy.isValid(bddContacts)) { deleteBddContacts(bddContacts); throw new InvalidCacheException(); } ArrayList<Contact> contacts = new ArrayList<>(); for (BddContact bddContact : bddContacts) { contacts.add(transform(bddContact, Contact.class)); } return contacts; } catch (java.sql.SQLException e) { throw new ObtainContactsBddException(); } catch (Throwable e) { throw new UnknownObtainContactsException(); } }
My way to clean Android v2
• Bussines logic doesn’t know where the data came from
• It’s easy to change data source implementation
• If you change the data sources implementation the business logic is not altered
Repository adavantages
My way to clean Android v2
Picassopublic interface ImageLoader { public void load(String url, ImageView imageView); public void loadCircular(String url, ImageView imageView); }
public class PicassoImageLoader implements ImageLoader { private Picasso picasso; @Override public void load(String url, ImageView imageView) { picasso.load(url).into(imageView); } @Override public void loadCircular(String url, ImageView imageView) { picasso.load(url).transform(new CircleTransform()).into(imageView); } }
My way to clean Android v2
ErrorManagerpublic interface ErrorManager { public void showError(String error); }
public class SnackbarErrorManagerImp implements ErrorManager { @Override public void showError(String error) { SnackbarManager.show(Snackbar.with(activity).text(error)); }
}
public class ToastErrorManagerImp implements ErrorManager { @Override public void showError(String error) { Toast.makeText(activity, error, Toast.LENGTH_LONG).show(); } }
My way to clean Android v2
• ALWAYS Depend upon abstractions, NEVER depend upon concretions
• Use a good naming, if there's a class you've created and the naming does not feel right, most probably it is wrong modeled.
• Create new shapes using the initial dartboard to ensure that it's placed on the corresponding layer
Tips
My way to clean Android v2
https://github.com/PaNaVTEC/Clean-Contacts
Show me the code!
My way to clean Android v2
• Fernando Cejas - Clean way
• Jorge Barroso - Arquitectura Tuenti
• Pedro Gomez - Dependency Injection
• Pedro Gomez - Desing patterns
• Uncle Bob - The clean architecture
• PaNaVTEC - Clean without bus
References
My way to clean Android v2
¿Questions?
Christian Panadero
http://panavtec.me @PaNaVTEC
Github - PaNaVTEC