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Example of using Dagger 2 in libraries
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| package com.example; | |
| import java.lang.annotation.Retention; | |
| import javax.inject.Inject; | |
| import javax.inject.Scope; | |
| import javax.inject.Singleton; | |
| import dagger.Binds; | |
| import dagger.BindsInstance; | |
| import dagger.Component; | |
| import dagger.Module; | |
| import dagger.Provides; | |
| import okhttp3.OkHttpClient; | |
| import static java.lang.annotation.RetentionPolicy.RUNTIME; | |
| /** | |
| * Example of using dagger in libraries. | |
| * <p> | |
| * Let's say we want to create a library that would provide us with users for specific social network. | |
| * We would name this library "UsersLibrary". This library depends on DataLibrary, which contains | |
| * domain models and repositories. | |
| * <p> | |
| * To make social networks pluggable we would need to provide different implementations | |
| * of the DataLibrary, for example: | |
| * * TwitterDataLibrary | |
| * * FacebookDataLibrary | |
| * * GoogleDataLibrary, | |
| * * etc. | |
| * <p> | |
| * Each of this libraries would depend on api libraries: | |
| * * TwitterApiLibrary | |
| * * FacebookApiLibrary | |
| * * GoogleApiLibrary | |
| */ | |
| public class ExperimentDagger { | |
| // | |
| // Api library | |
| // | |
| public static class FacebookApi { | |
| @Inject | |
| public FacebookApi(OkHttpClient client) { | |
| } | |
| } | |
| interface FacebookApiLibrary { | |
| FacebookApi api(); | |
| } | |
| @Component | |
| interface FacebookApiComponent extends FacebookApiLibrary { | |
| @Component.Builder | |
| interface Builder { | |
| @BindsInstance | |
| Builder client(OkHttpClient client); | |
| FacebookApiComponent build(); | |
| } | |
| } | |
| // | |
| // Data Library (domain layer) | |
| // | |
| public interface UsersData { | |
| } | |
| public interface UsersDataLibrary { | |
| UsersData usersData(); | |
| } | |
| // | |
| // Facebook implementation of the UsersData | |
| // | |
| public static class FacebookUsersData implements UsersData { | |
| @Inject | |
| public FacebookUsersData(FacebookApi api) { | |
| } | |
| } | |
| @Module | |
| interface FacebookUsersDataModule { | |
| @Binds | |
| UsersData bindsUsersData(FacebookUsersData data); | |
| } | |
| @Component( | |
| modules = FacebookUsersDataModule.class, | |
| dependencies = FacebookApiLibrary.class | |
| ) | |
| interface FacebookUsersDataComponent extends UsersDataLibrary { | |
| @Component.Builder | |
| interface Builder { | |
| Builder apiLibrary(FacebookApiLibrary api); | |
| FacebookUsersDataComponent build(); | |
| } | |
| } | |
| // | |
| // Main Library that uses Data | |
| // | |
| public static class UsersApp { | |
| @Inject | |
| public UsersApp(UsersDataLibrary data) { | |
| } | |
| public void hello() { | |
| System.out.println("Hello!"); | |
| } | |
| } | |
| interface UsersLibrary { | |
| UsersApp users(); | |
| } | |
| @Component(dependencies = UsersDataLibrary.class) | |
| interface UsersLibraryComponent extends UsersLibrary { | |
| @Component.Builder | |
| interface Builder { | |
| Builder dataLibrary(UsersDataLibrary dataLib); | |
| UsersLibrary build(); | |
| } | |
| } | |
| /** | |
| * Using library from application if app is not using Dagger | |
| */ | |
| public static void usingLibrary() { | |
| OkHttpClient client = new OkHttpClient(); | |
| FacebookApiLibrary apiLib = DaggerExperimentDagger_FacebookApiComponent.builder() | |
| .client(client) | |
| .build(); | |
| UsersDataLibrary dataLib = DaggerExperimentDagger_FacebookUsersDataComponent.builder() | |
| .apiLibrary(apiLib) | |
| .build(); | |
| UsersLibrary usersLibrary = DaggerExperimentDagger_UsersLibraryComponent.builder() | |
| .dataLibrary(dataLib) | |
| .build(); | |
| usersLibrary.users().hello(); | |
| } | |
| // | |
| // If client app using dagger, we can create separate module to bind them all. | |
| // | |
| // Or you could have separate "integration" library that provides module or component. | |
| // | |
| @Scope | |
| @Retention(RUNTIME) | |
| public @interface ApiLibScope { | |
| } | |
| @Module(includes = NetworkModule.class) | |
| class FacebookUsersModule { | |
| @Provides | |
| @Singleton | |
| UsersLibrary providesUsersLibrary(UsersDataLibrary data) { | |
| return DaggerExperimentDagger_UsersLibraryComponent.builder() | |
| .dataLibrary(data) | |
| .build(); | |
| } | |
| @Provides | |
| @Singleton | |
| UsersDataLibrary providesUsersDataLibrary(FacebookApiLibrary apiLib) { | |
| return DaggerExperimentDagger_FacebookUsersDataComponent.builder() | |
| .apiLibrary(apiLib) | |
| .build(); | |
| } | |
| @Provides | |
| @Singleton | |
| FacebookApiLibrary providesFacebookApiLibrary(@ApiLibScope OkHttpClient client) { | |
| return DaggerExperimentDagger_FacebookApiComponent.builder() | |
| .client(client) | |
| .build(); | |
| } | |
| } | |
| @Module | |
| class NetworkModule { | |
| @Provides | |
| @ApiLibScope | |
| OkHttpClient providesOkHttpClient() { | |
| return new OkHttpClient(); | |
| } | |
| } | |
| } |
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