Kotlin：Dagger2 @Inject context var始终为空

我正在尝试在AndroidStudio中与Android没有连接的模块，它没有任何活动，但我需要上下文像房间数据库的几件事情。

这是我的设置：

AppComponent

@Singleton @Component(modules = arrayOf(AndroidSupportInjectionModule::class, AppModule::class)) interface AppComponent : AndroidInjector<NexoApplication> { @Component.Builder interface Builder { @BindsInstance fun application(application: NexoApplication): Builder fun build(): AppComponent } override fun inject(app: NexoApplication) } 

的AppModule

 @Module class AppModule { @Singleton @Provides fun provideLogger(application: NexoApplication) = LogNexoManager(application) } 

AppLifecycleCallbacks

 interface AppLifecycleCallbacks { fun onCreate(application: Application) fun onTerminate(application: Application) } 

应用

 class NexoApplication: DaggerApplication() { @Inject lateinit var appLifecycleCallbacks: AppLifecycleCallbacks override fun applicationInjector() = DaggerAppComponent.builder() .application(this) .build() override fun onCreate() { super.onCreate() appLifecycleCallbacks.onCreate(this) } override fun onTerminate() { appLifecycleCallbacks.onTerminate(this) super.onTerminate() } } 

AndroidManifest.xml中

 <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" package="com.elstatgroup.elstat"> <application android:name="com.elstatgroup.elstat.NexoApplication" android:allowBackup="true" android:label="@string/app_name" android:supportsRtl="true"> </application> 

而我尝试注入上下文到我的主类是这样的：

 class LogNexoManager(app: Application){ var logRepository: LogRepository init { logRepository = LogRepositoryImpl(app) } } 

抽样单元测试总是假的

  @Test fun proceedWithLogs(){ val logManager = LogManager() } 

而例外是：

kotlin.UninitializedPropertyAccessException：lateinit属性应用程序尚未初始化

更新：我做了@Emanuel S提出的更改，现在我有一个错误：

错误：任务'：nexo：kaptDebugKotlin'的执行失败。 内部编译器错误。 查看日志了解更多详情

我的Build.gradle文件是：

 apply plugin: 'com.android.library' apply plugin: 'kotlin-android' apply plugin: 'kotlin-kapt' android { compileSdkVersion 26 defaultConfig { minSdkVersion 15 targetSdkVersion 26 versionCode 1 versionName "1.0" testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner" } buildTypes { release { minifyEnabled false proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro' } } 

}

 ext.daggerVersion = '2.11' ext.roomVersion = '1.0.0-alpha9' dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation 'com.android.support:appcompat-v7:26.1.0' testImplementation 'junit:junit:4.12' androidTestImplementation('com.android.support.test.espresso:espresso-core:3.0.1', { exclude group: 'com.android.support', module: 'support-annotations' }) compile "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version" // RxJava implementation 'io.reactivex.rxjava2:rxjava:2.1.0' implementation 'io.reactivex.rxjava2:rxandroid:2.0.1' // Room implementation "android.arch.persistence.room:runtime:$roomVersion" implementation "android.arch.persistence.room:rxjava2:$roomVersion" kapt "android.arch.persistence.room:compiler:$roomVersion" compile "org.jetbrains.kotlin:kotlin-stdlib:1.1.51" androidTestImplementation "android.arch.persistence.room:testing:$roomVersion" compile "com.google.dagger:dagger:$daggerVersion" compile "com.google.dagger:dagger-android:$daggerVersion" compile "com.google.dagger:dagger-android-support:$daggerVersion" kapt "com.google.dagger:dagger-android-processor:$daggerVersion" kapt "com.google.dagger:dagger-compiler:$daggerVersion" implementation "com.google.dagger:dagger-android-support:2.11-rc2" // version may be not up 2 date later. } repositories { mavenCentral() } 

Answer 1

这是一个简单的测试用例。 没有测试，但应该显示你应该如何注入你的LogManager的概念。

 @Singleton @Component(modules = arrayOf(AndroidSupportInjectionModule::class, AppModule::class)) interface AppComponent : AndroidInjector<App> { { @Component.Builder interface Builder { @BindsInstance fun application(application: App): Builder fun build(): AppComponent } override fun inject(app: App) } @Module class AppModule { @Singleton @Provides fun provideYourDb(application: App) = Room.databaseBuilder(application, YourDb::class.java, "your.db").build() @Singleton @Provides fun provideLogger(application: App) = LogManager(application) } 

应用程序生命周期的界面。

 interface AppLifecycleCallbacks { fun onCreate(application: Application) fun onTerminate(application: Application) } 

你的应用程序应该扩展DaggerApplication（）。

 class App:DaggerApplication() { @Inject lateinit var appLifecycleCallbacks: AppLifecycleCallbacks override fun applicationInjector() = DaggerAppComponent.builder() .application(this) .build() override fun onCreate() { super.onCreate() appLifecycleCallbacks.onCreate(this) } override fun onTerminate() { appLifecycleCallbacks.onTerminate(this) super.onTerminate() } } 

最后你有一个提供的LogManager。

 class LogManager (val app: App) 

如果你真的想在你的LogManager中使用@Inject，你可以使用fun inject(logManager: LogManager)将它注入到你的AppComponent中。

生命周期界面用于自动注入活动/服务，以备日后扩展。 例：

应用程序入口类

 override fun onCreate() { super.onCreate() applyAutoInjector() appLifecycleCallbacks.onCreate(this) } fun Application.applyAutoInjector() = registerActivityLifecycleCallbacks( object : Application.ActivityLifecycleCallbacks { override fun onActivityCreated(activity: Activity, savedInstanceState: Bundle?) { handleActivity(activity) } //truncated ... }) 

请注意，您需要在您的Gradle中使用dagger-android-support的依赖，才能拥有AndroidSupportInjectionModule。

 implementation "com.google.dagger:dagger-android-support:2.11-rc2" // version may be not up 2 date later.