Android中Hilt的简单使用

前言：

一、Android Hilt依赖注入框架的引入步骤如下：

1.引入Hilt,在App的Build.gradle目录下添加hilt插件和依赖:

plugins {
    id 'com.android.application'
    id 'kotlin-android'
    id 'kotlin-kapt'
    id 'dagger.hilt.android.plugin'
}

  //Dagger - Hilt
    implementation "com.google.dagger:hilt-android:2.30"
    kapt "com.google.dagger:hilt-android-compiler:2.30"

    implementation "androidx.hilt:hilt-lifecycle-viewmodel:1.0.0-alpha03"
    kapt "androidx.hilt:hilt-compiler:1.0.0"
    
    // Activity KTX for viewModels()
    implementation "androidx.activity:activity-ktx:1.3.1"

2.在项目的build.gradle目录下添加hilt的插件依赖:

buildscript {
    ext.kotlin_version = "1.5.21"
    repositories {
        google()
        jcenter()
    }
    dependencies {
        classpath "com.android.tools.build:gradle:4.1.1"
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        classpath "com.google.dagger:hilt-android-gradle-plugin:2.28.3-alpha"
        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

3.在项目中使用Java8

  compileOptions {
      sourceCompatibility JavaVersion.VERSION_1_8
      targetCompatibility JavaVersion.VERSION_1_8
  }
  kotlinOptions {
      jvmTarget = '1.8'
  }

二、Hilt的简单使用

1.创建App类，继承于Application

​

 @HiltAndroidApp
class App :Application(){

}

2.在Manifast中注册Application

3.将依赖注入到MainActivity类

注:在 Application 类中设置了 Hilt 且有了应用级组件后，Hilt 可以为带有 @AndroidEntryPoint 注释的其他 Android 类提供依赖项

Hilt 目前支持以下 Android 类：
Application（通过使用 @HiltAndroidApp）
Activity
Fragment
View
Service
BroadcastReceiver

4.创建注入类:

@Module
@InstallIn(ActivityComponent::class)
object MainModule {
    @ActivityScoped
    @Provides
    @Named("String2")
    fun provideTestString2(
        @ApplicationContext context: Context,
        @Named("String1") testString1: String
    ) = "${context.getString(R.string.string_to_inject)} - $testString1"
}

@Module
@InstallIn(ApplicationComponent::class)
object AppModule {
    @Singleton
    @Provides
    @Named("String1")
    fun provideTestString1() = "This is a string we will inject"
}

class TestViewModel @ViewModelInject constructor(@Named("String2") testString2: String)
    :ViewModel(){
    init {
        Log.d("ViewModel", "Test String from ViewModel: $testString2")
    }
}

5.把创建好的测试类注入到MainActivity中:

@Inject
@Named("String1")
lateinit var testString: String
private val viewModel: TestViewModel by viewModels()

override fun onCreate(savedInstanceState: Bundle?) {
  super.onCreate(savedInstanceState)
  setContentView(R.layout.activity_main)
  Log.d("MainActivity", "Test String from MainActivity: $testString")
  viewModel
}

6.运行结果如下：

7.完整的demo地址：

hint的简单使用

8.参考资料：

hint参考资料