JetpackCompose使用Hilt依赖注入+DataStore键值存储踩坑记录

2025.2.26

依赖库需求

项目级build.gradle

buildscript {
    dependencies {
        classpath ("com.google.dagger:hilt-android-gradle-plugin:2.51.1") //  Hilt 插件,建议自动修复到最新版,版本过低会出现 viewmodel阶段的<init>异常
    }
}

模块级build.gradle

plugins {
    id("kotlin-kapt")
    id ("dagger.hilt.android.plugin")
}
dependencies {
implementation (libs.androidx.datastore.preferences)
implementation("androidx.lifecycle:lifecycle-viewmodel-compose:2.8.4")
   implementation (libs.hilt.android)
   kapt (libs.hilt.compiler)
   }

实现操作

新建APP类,添加hilt注解

package com.luoling.yoruplayermobile

import android.app.Application
import dagger.hilt.android.HiltAndroidApp

@HiltAndroidApp
class YoruApplication : Application() 

在MainActivity里打上Hilt入口注解

@AndroidEntryPoint
class MainActivity : ComponentActivity() {....}

修改manifest

<application
android:name=".YoruApplication">
......

封装DataStore,读取用flow处理实现自动更新

class DataStoreManager(private val dataStore:DataStore<Preferences>) {
    
    suspend fun  editPreference(key:String,value:String){
        val stringKey=stringPreferencesKey(key)
        dataStore.edit { preferences ->
            preferences[stringKey]=value
         }
    }
    fun readPreference(key:String):Flow<String>{
        val stringKey=stringPreferencesKey(key)
        return dataStore.data.map { 
            preferences ->
            preferences[stringKey]?:"null"
         }
    }
    suspend fun editIntPreference(key: String, value: Int) {
        val intKey = intPreferencesKey(key)
        dataStore.edit { preferences ->
            preferences[intKey] = value
        }
    }
    
    fun readIntPreference(key: String): Flow<Int> {
        val intKey = intPreferencesKey(key)
        return dataStore.data.map { preferences ->
            preferences[intKey] ?: 0 
        }
    }
    
    
}

di层实现提供单例,最新版DataStore需要使用工厂,hilt自动解析provides注解提供的函数池寻找填充隐式依赖完成依赖链

@Module
@InstallIn(SingletonComponent::class)
class DataStoreModule {
    
    @Provides
    @Singleton
    fun providePreferencesDataStore(@ApplicationContext context:Context):DataStore<Preferences>{
        return PreferenceDataStoreFactory.create (
             produceFile = { context.preferencesDataStoreFile("settings") }
         )
    }
    
    @Provides
    @Singleton
    fun provideDataStoreManager(dataStore: DataStore<Preferences>):DataStoreManager{
        return DataStoreManager(dataStore)
    }
    
}

ViewModel中使用hiltviewmodel和inject注解完成注入

@HiltViewModel
class UserHomeViewModel @Inject constructor(
    private val dataStoreManager: DataStoreManager 
) : ViewModel() {
    var tmp by mutableStateOf("114514")
        private set // 限制仅在 ViewModel 内修改

    suspend fun savePreference(key: String, value: String) {
        dataStoreManager.editPreference(key, value)
    }
        init {
            viewModelScope.launch {
                dataStoreManager.readPreference("key")
                    .collect { value ->
                        tmp = value
                    }
            }
        }

}