Порядочные связи вместе с Dagger2

Andrii Horishnii - android developer at Ekreative
Часом буває так, що треба додати малесеньку фічу до майже готового проекту. Щоб цей процес не спричиняв головного болю через сильну зв’язність компонентів проекту - слід зазадалегідь потурбуватися про залежності.
Як зробити життя простішим собі та іншим? Дізнаємось вже цієї суботи та розглянемо як зконфігурувати фреймворк Dagger2 для вашого android додатку

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1. Порядочные связи вместе с Dagger 2 Andrii Horishnii Android developer at eKreative
2. OH NO! IT’S TERRIBLE!
3. SOLID Single responsibility principle Open/closed principle Liskov substitution principle Interface segregation principle Dependency inversion principle
4. Dependency inversion principle public interface NotificationHelper { void showNotification(String message); } public class NotificationHelperImpl implements NotificationHelper { private Context mContext; public NotificationHelperImpl(Context context) { mContext = context; } @Override public void showNotification(String message) { Toast.makeText(mContext, message, Toast.LENGTH_LONG).show(); } }
5. Dependency inversion principle public class MainActivity extends AppCompatActivity { private NotificationHelper mNotificationHelper; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mNotificationHelper = new NotificationHelperImpl(this); mNotificationHelper.showNotification("It's work! :)"); } }
6. JSR-330 (javax.inject) @Inject Identifies injectable constructors, methods, and fields. @Named String-based qualifier. @Qualifier Identifies qualifier annotations. @Scope Identifies scope annotations. @Singleton Identifies a type that the injector only instantiates once.
7. @Inject public class MainActivityPresenterImpl implements MainActivityPresenter { private NotificationHelper mNotificationHelper; private SaturnMoonsModel mSaturnMoonsModel; @Inject public MainActivityPresenterImpl(NotificationHelper notificationHelper, SaturnMoonsModel saturnMoonsModel) { mNotificationHelper = notificationHelper; mSaturnMoonsModel = saturnMoonsModel; } }
8. @Inject public class MainActivityPresenterImpl implements MainActivityPresenter { @Inject NotificationHelper mNotificationHelper; @Inject SaturnMoonsModel mSaturnMoonsModel; @Inject public MainActivityPresenterImpl() { } }
9. @Inject public class MainActivityPresenterImpl implements MainActivityPresenter { ... @Inject public MainActivityPresenterImpl() { } @Inject public void setNotificationHelper(NotificationHelper notificationHelper) { mNotificationHelper = notificationHelper; } @Inject public void setSaturnMoonsModel(SaturnMoonsModel saturnMoonsModel) { mSaturnMoonsModel = saturnMoonsModel; } }
10. Dagger2 basics Module Modules provide dependencies through public methods that return the objects they provide. Provides Method to satisfy a dependency. The method’s return type defines which dependency it satisfies. Component Components are the objects that requesters contact for dependencies.
11. @Module @Module public class AppModule { private Application mApplication; public AppModule(Application application) { mApplication = application; } ... }
12. @Module @Module(includes = {PresenterModule.class}) public class HelperModule { ... }
13. @Provides @Module public class AppModule { private Application mApplication; public AppModule(Application application) { mApplication = application; } @Provides Context provideContext() { return mApplication; } }
14. @Provides @Module public class AppModule { @Provides @Singleton SharedPreferences provideSharedPreferences(Context context) { return context.getSharedPreferences("data", Context.MODE_PRIVATE); } @Provides @Named("AnotherPreferences") SharedPreferences provideAnotherSharedPreferences(Context context) { return context.getSharedPreferences("another", Context.MODE_PRIVATE); } }
15. @Provides @Module public class PresenterModule { @Provides MainActivityPresenter providePresenter(MainActivityPresenterImpl presenter) { return presenter; } } public class MainActivityPresenterImpl implements MainActivityPresenter { @Inject public MainActivityPresenterImpl(NotificationHelper notificationHelper, SaturnMoonsModel saturnMoonsModel) { ... } }
16. @Component @Singleton @Component(modules = {AppModule.class, HelperModule.class}) public interface AppComponent { void inject(MyActivity activity); void inject(MyFragment fragment); void inject(MyService service); }
17. @Component public class AppClass extends Application { private AppComponent mAppComponent; @Override public void onCreate() { super.onCreate(); mAppComponent = DaggerAppComponent.builder() .appModule(new AppModule(this)) .build(); } public static AppComponent getAppComponent(Context context) { return ((AppClass) context.getApplicationContext()).mAppComponent; } }
18. @Inject into Android classes public class MainActivity extends AppCompatActivity { @Inject NotificationHelper mNotificationHelper; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); AppClass.getAppComponent(this).inject(this); mNotificationHelper.showNotification("It's work! :)"); } }
20. @Component @Singleton @Component(modules = {AppModule.class, HelperModule.class}) public interface AppComponent { ... NotificationHelper getNotificationHelper(); } mNotificationHelper = getAppComponent().getNotificationHelper();
21. @Scope @Scope @Retention(RUNTIME) public @interface ActivityScope {} AppComponent ActivityComponent (@ActivityScope) ActivityComponent (@ActivityScope) ActivityComponent (@ActivityScope)
22. @Subcomponent @ActivityScope @Subcomponent(modules = {PresenterModule.class}) public interface ActivityComponent { void inject(MainActivity activity); } @Singleton @Component(modules = {AppModule.class, HelperModule.class}) public interface AppComponent { ActivityComponent plusActivityComponent(); ... }
23. @Subcomponent public class MainActivity extends AppCompatActivity implements MainView { @Inject MainActivityPresenter mPresenter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); ActivityComponent activityComponent = AppClass.getAppComponent(this).plusActivityComponent(); activityComponent.inject(this); } }