本文适宜有肯定的Dagger2应用根底的同学
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前两篇文章咱们讲了两种多模块我的项目怎么应用Dagger2。
发现在每个Activity的onCreate中都须要调一个inject办法
NewsComponentHolder.newsComponent.inject(this)UserComponentHolder.userComponent.inject(this)其实还能够用dagger2专给android应用的dagger.android来简化这种操作。
先看一般多模块我的项目
咱们在Dagger2多模块我的项目Component组织形式抉择(一)的根底上革新实现
dagger.android的核心思想是在每个Component收集两个Map
Map<Class<?>, Provider<AndroidInjector.Factory<?>>> injectorFactoriesWithClassKeysMap<String, Provider<AndroidInjector.Factory<?>>> injectorFactoriesWithStringKeys这两个Map定义在AndroidInjectionModule中
@Beta@Modulepublic abstract class AndroidInjectionModule { @Multibinds abstract Map<Class<?>, AndroidInjector.Factory<?>> classKeyedInjectorFactories(); @Multibinds abstract Map<String, AndroidInjector.Factory<?>> stringKeyedInjectorFactories(); private AndroidInjectionModule() {}}dagger.android会把把收集到的这两个Map注入到DispatchingAndroidInjector中，dagger.android就是通过这个DispatchingAndroidInjector注入到Activity,Fragment中
怎么收集呢
首先定义一个 xxxBindModule ，将要注入的Activity,fragment用@ContributesAndroidInjector注解
dagger.android会把这些收集到后面的Map中去
@Module(includes = [AndroidInjectionModule::class])abstract class NewsBindModule { @ContributesAndroidInjector abstract fun newsActivity(): NewsActivity}而后相应的Component的modules加上xxxBindModule,
去掉inject(XXXActivity)这样的一大堆申明办法,洁净多了
@NewsScope@Subcomponent(modules = [NewsModule::class, NewsBindModule::class])interface NewsComponent { @Subcomponent.Factory interface Factory { fun create(): NewsComponent }}之后依照dagger.android用法要让Application实现HasAndroidInjector接口，并注入dispatchingAndroidInjector实例
class AppApplication : BaseApplication(), NewsComponentProvider, UserComponentProvider, HasAndroidInjector { @Inject lateinit var dispatchingAndroidInjector: DispatchingAndroidInjector<Any> lateinit var appComponent: AppComponent override fun onCreate() { super.onCreate() appComponent = DaggerAppComponent.factory().create(this) } override fun provideNewsComponent(): NewsComponent { return appComponent.newsComponentFactory().create() } override fun provideUserComponent(): UserComponent { return appComponent.userComponentFactory().create() } override fun androidInjector(): AndroidInjector<Any> { return dispatchingAndroidInjector }}再在Component加上一个注入到下面Appliction的办法(因为news模块拿不到AppApplication的援用，间接注入到Any好了)
@NewsScope@Subcomponent(modules = [NewsModule::class, NewsBindModule::class])interface NewsComponent { @Subcomponent.Factory interface Factory { fun create(): NewsComponent } fun inject(any: Any)}而后在AppApplication中注入
class AppApplication : BaseApplication(), NewsComponentProvider, UserComponentProvider { @Inject lateinit var dispatchingAndroidInjector: DispatchingAndroidInjector<Any> lateinit var appComponent: AppComponent override fun onCreate() { super.onCreate() appComponent = DaggerAppComponent.factory().create(this) NewsComponentHolder.newsComponent.inject(this) } override fun provideNewsComponent(): NewsComponent { return appComponent.newsComponentFactory().create() } override fun provideUserComponent(): UserComponent { return appComponent.userComponentFactory().create() } override fun androidInjector(): AndroidInjector<Any> { return dispatchingAndroidInjector }}最初在Activity，fragment的onCreate办法中退出AndroidInjection.inject(this),留神要放在super.onCreate(savedInstanceState)后面,咱们把这一步放在BaseActivity,BaseFragment里
open class BaseActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { AndroidInjection.inject(this) super.onCreate(savedInstanceState) }}而后Activity只有继承BaseActivity就能够了，不须要写任何注入代码了，像平时应用一样了，想要注入对象的变量加 @Inject就能够了
class NewsActivity : BaseActivity() { @Inject lateinit var set: Set<String> override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_news) text.text = set.toString() }}这种写法对于单模块我的项目没有问题，然而对多模块我的项目来说这有问题了，下面咱们只注入了news模块的，user模块的没有。咱们有多个Component,然而这里只有一个dispatchingAndroidInjector，你用哪个Component注入都不全，前面注入的会笼罩后面注入的。所以这里要革新下
从后面咱们晓得一个Component最终生成一个DispatchingAndroidInjector，多个Component咱们把它们都收集起来
咱们先定义一个BaseDispatchingInjector,它相当于后面的AppApplication,接管一个Component注入的DispatchingAndroidInjector
class BaseDispatchingInjector { @Inject lateinit var dispatchingAndroidInjector: DispatchingAndroidInjector<Any>}而后把每个Component里的inject(any: Any)改成inject(baseDispatchingInjector: BaseDispatchingInjector)
@NewsScope@Subcomponent(modules = [NewsModule::class, NewsBindModule::class])interface NewsComponent { @Subcomponent.Factory interface Factory { fun create(): NewsComponent } fun inject(baseDispatchingInjector: BaseDispatchingInjector)}@UserScope@Subcomponent(modules = [UserModule::class, UserBindModule::class])interface UserComponent { @Subcomponent.Factory interface Factory { fun create(): UserComponent } fun inject(baseDispatchingInjector: BaseDispatchingInjector)}这样注入
val userDispatchingInjector = BaseDispatchingInjector()UserComponentHolder.userComponent.inject(userDispatchingInjector)val newsDispatchingInjector = BaseDispatchingInjector()NewsComponentHolder.newsComponent.inject(newsDispatchingInjector)这样咱们每个模块都失去一个BaseDispatchingInjector,并且外面每个Activity,Fragment对应的Map都注入好了
而后就要定义一个MultiModuleAndroidInjector把每个模块的BaseDispatchingInjector整合到一起成为一个独自的AndroidInjector
class MultiModuleAndroidInjector : AndroidInjector<Any> { private val injectors = mutableListOf<BaseDispatchingInjector>() fun addInjector(injector: HasDispatchingInjector) { injectors.add(injector) } override fun inject(instance: Any) { val wasInjected = injectors.any { it.dispatchingAndroidInjector.maybeInject(instance) } if (!wasInjected) { throw IllegalArgumentException("injection failed") } }}这个MultiModuleAndroidInjector在注入的时候会每个BaseDispatchingInjector都去尝试看能不能注入，这样就把所有Component的注解都遍历了
看AppApplication最初实现
class AppApplication : BaseApplication(), NewsComponentProvider, UserComponentProvider, HasAndroidInjector { lateinit var appComponent: AppComponent private val multiModuleAndroidInjector = MultiModuleAndroidInjector() override fun onCreate() { super.onCreate() appComponent = DaggerAppComponent.factory().create(this) val userDispatchingInjector = BaseDispatchingInjector() UserComponentHolder.userComponent.inject(userDispatchingInjector) multiModuleAndroidInjector.addInjector(userDispatchingInjector) val newsDispatchingInjector = BaseDispatchingInjector() NewsComponentHolder.newsComponent.inject(newsDispatchingInjector) multiModuleAndroidInjector.addInjector(newsDispatchingInjector) } override fun provideNewsComponent(): NewsComponent { return appComponent.newsComponentFactory().create() } override fun provideUserComponent(): UserComponent { return appComponent.userComponentFactory().create() } override fun androidInjector(): AndroidInjector<Any> { return multiModuleAndroidInjector }}代码地址