"[PL] MVP do MVVM - separacja warstw w aplikacji androidowej" by Konrad Morawski - presentation shown during meet.mobile Szczecin in September 2015.

1. Konrad Morawski
MVP do MVVM
separacja warstw w aplikacji androidowej

2. 2
Model-View-Presenter
Wczesne lata 90.
Model-View-ViewModel
2005 r.

3. 3
Bez rozdziału
▪Co robią Activities
▪co powinny
▪uruchamianie usług
▪komunikacja z API
▪obsługa user input
▪obsługa bazy
▪I/O
▪zarządzanie fragmentami
▪występy w reality show
▪jazda autostopem

4. MVP
VIEW MODELPRESENTER

5. MVP
public class RegistrationActivity implements RegistrationScreen {
// ...
@Override
public void goToNextStep() {
viewSwitcher.showNext();
}
@Override
public void showNumberInputError() {
String errorMessage = resources.getString(R.string.registration_number_validation);
numberInput.setError(errorMessage);
}
@Override
public void showPinInputError(int validLength) {
pinInput.setError(resources.getString(R.string.registration_code_validation, validLength));
}
@Override
public void showProgressDialog() {
progressDialog.show();
}
// ...

6. MVP
public class RegistrationActivity implements RegistrationScreen {
// ...
@Override
public void goToNextStep() {
viewSwitcher.showNext();
}
@Override
public void showNumberInputError() {
String errorMessage = resources.getString(R.string.registration_number_validation);
numberInput.setError(errorMessage);
}
@Override
public void showPinInputError(int validLength) {
pinInput.setError(resources.getString(R.string.registration_code_validation, validLength));
}
@Override
public void showProgressDialog() {
progressDialog.show();
}
// ...

7. MVP
public class RegistrationPresenter {
public RegistrationPresenter(RegistrationScreen screen) {
this.screen = screen;
}
public void sendNumber(String phoneNumber, String selectedCode) {
String normalizedNumber = phoneNumberNormalizer.normalizePhoneNumber(phoneNumber, selectedCode);
if (normalizedNumber == null) {
screen.showNumberInputError();
return;
}
RegistrationRequest request = new RegistrationRequest(normalizedNumber);
api.postRequest(request);
screen.goToNextStep();
}
public void sendPin(String pin) {
if (pin.length() != EXPECTED_PIN_LENGTH) {
screen.showPinInputError(EXPECTED_PIN_LENGTH);
return;
}
CreateAccountRequestEvent event = new Event.CreateAccountRequestEvent(pin);
eventBus.postEvent(event);
screen.showProgressDialog();

8. MVP
public class RegistrationPresenter {
public RegistrationPresenter(RegistrationScreen screen) {
this.screen = screen;
}
// ...
public class RegistrationActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_registration);
presenter = new RegistrationPresenter(this);
// ...
@OnClick (R.id.login_button)
void onLoginClicked() {
presenter.submitInput();
}

9. MVP
VIEW PRESENTER?

10. MVP
public RegistrationPresenter(RegistrationScreen screen) {
this.screen = screen;
}
public interface RegistrationScreen extends Screen {
void dismissProgressDialog();
void goToNextStep();
void showInfoDialog(int titleResId, int infoResId, String dialogInfoTag);
void showNumberInputError();
void showPinInputError(int validLength);
void showProgressDialog();
void clearPinInput();
// ...
}
public class RegistrationActivity implements RegistrationScreen

11. MVP
VIEW PRESENTER
~SCREEN

12. MVP – testy
@Override
protected void setUp() throws Exception {
super.setUp();
screen = mock(RegistrationScreen.class);
presenter = new RegistrationPresenter(screen, null);
}
/**
* Once Presenter gets notified an account was successfully created,
* it must request from the Screen that we move on to the next screen
*/
public void testRegistration_whenAccountCreated_requestsOpeningAnotherActivity() {
// ACT
presenter.handleCreateAccountResponse(successfullyCreatedAccountResponse());
// ASSERT
verify(screen).goToNextScreen();
verify(screen, never()).showNumberInputError();
}

13. MVP – testy
@Override
protected void setUp() throws Exception {
screen = mock(RegistrationScreen.class);
screen = new RegistrationScreen() {
boolean goToNextScreenCalled;
@Override
public void goToNextScreen() {
goToNextScreenCalled = true;
}
// ...
}
// ASSERT
verify(screen).goToNextScreen();
assertTrue(screen.goToNextScreenCalled);

14. MVP – elastyczność
Presenter A View 1
Presenter A View 2
View 1 Presenter A
View 1 Presenter B
MegapresenterÜberview
Presenter A View 1 Presenter B View 2

15. MVP – elastyczność
Blokada PIN
Ustawianie (powtórzenie 2x)
Tryb blokady (bez rezygnacji)
Wyłączanie (z rezygnacją)

16. MVP – elastyczność
PinPresenter presenter;
protected void onCreate(Bundle savedInstanceState) {
this.screenMode = savedInstanceState.getSerializable(...);
this.presenter = presenterFactory.createPresenterFor(screenMode);
}
@OnClick (R.id.login_button)
void onLoginClicked() {
presenter.submitInput();
}

17. 17
PinProtectionPresenter
extends PinPresenter {
@Override
public void submitInput() {
String input = scr.getUserInput();
if (!isPinValid(input)) {
return;
}
if (isCorrect(userInput)) {
letUserIn(userInput);
} else {
screen.clear();
rejectUser();
}
}
PinSubmissionPresenter
extends PinPresenter {
@Override
public void submitInput() {
String input = scr.getUserInput();
if (!isPinValid(input)) {
return;
}
switch (currentStep) {
case ENTER_NEW:
newPin = input;
moveToNextStep();
break;
case CONFIRM_NEW:
if (input == newPin) {
pinManager.savePin(newPin);
pinManager.setEnabled(true);
moveToNextStep();
MVP – elastyczność

18. 18
MVP – elastyczność

19. 19
Mosby
http://hannesdorfmann.com/mosby
Nucleus
https://github.com/konmik/nucleus
MVP – frameworki

20. 20
MVP – podsumowanie
łatwe
dumb View
Presenter wie jak aplikacja działa
Presenter nie wie, że jest w Androidzie
testowalność, elastyczność, radość

21. MVVM
VIEW MODELViewModel
https://developer.android.com/tools/data-binding/guide.html

22. 22
M V VM
<layout>
<data>
<import
alias="Message"
type="blstream.kmw.mvvmtest.MessageViewModel" />
<variable
name="message"
type="Message" />
</data>
...
<TextView
android:text="@{message.title}"
...
/>

23. 23
M V VM
<LinearLayout>
<TextView
android:text="@{message.title}"
.../>
<TextView
android:text="@{message.body}"
.../>
public final class MessageViewModel {
private final String title;
private final String body;
public String getTitle() {
return title;
}
public String getBody() {
return body;
}
}

24. 24
M V VM
<LinearLayout>
<TextView
android:text="@{message.title}"
.../>
<TextView
android:text="@{message.body}"
.../>
public final class MessageViewModel {
private final String title;
private final String body;
public String getTitle() {
return title;
}
public String getBody() {
return body;
}
}
ActivityMessageBinding binding = DataBindingUtil.setContentView(this, R.layout.act_message);
MessageViewModel viewModel = new MessageViewModel();
binding.setMessage(viewModel);

25. 25
M V VM
private static class User extends BaseObservable {
private String name;
@Bindable
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
notifyPropertyChanged(BR.name);
}
}

26. Data Binding
android:text="@{user.lastName}"
android:visibility="@{user.isAdult ? View.VISIBLE : View.GONE}"
android:text="@{MyStringUtils.capitalize(user.lastName)}"
android:visibility="@{age &lt; 13 ? View.GONE : View.VISIBLE}"
android:transitionName='@{"image_" + id}'

27. Data Binding
android:text="@{user.displayName ?? user.lastName}"
android:padding="@{large?
@dimen/largePadding : @dimen/smallPadding}"
android:background="@{isError ? @color/red : @color/white}"
app:addTextChangedListener="@{viewModel.nameWatcher}"
app:onFocusChangeListener="@{viewModel.nameFocusListener}"

28. 28
MVVM – BindingAdapter
@BindingAdapter("bind:imageUrl")
public static void loadImage(ImageView imageView, String url) {
Picasso
.with(imageView.getContext())
.load(url)
.into(imageView);
}

29. 29
MVVM
public class LoginViewModel {
String email;
String password;
boolean loginEnabled;

30. 30
MVVM – dlaczego?
testowalność
mniej kodu
reużywalność
praca nad UI – bezpośrednio w
„materiale”

31. 31
MVVM – podsumowanie
View: żadnych więcej @id
ViewModel: modeluje widok
Brakuje:
Two-Mode
pełna obsługa list (do uzupełnienia)
wsparcie w IDE
gwarancja stabilności / wstecznej kompatybilności

32. 32
Podsumowanie
chude Activity
warto używać MVP, nawet zrobionego w piwnicy
MVVM = nadchodzący standard (prawdopodobnie)

33. Konrad Morawski
Software Engineer
konrad.morawski@blstream.com
Dzięki