我正在使用 Kotlin 实现 Room 持久性库来实现我的数据库。
以下是我的 Entity、Dao 和 Database 类：
Food.kt
@Entity
class Food(@ColumnInfo(name = "food_name") var foodName: String,
@ColumnInfo(name = "food_desc") var foodDesc: String,
@ColumnInfo(name = "protein") var protein: Double,
@ColumnInfo(name = "carbs") var carbs: Double,
@ColumnInfo(name = "fat") var fat: Double)
{
@ColumnInfo(name = "id")
@PrimaryKey(autoGenerate = true)
var id: Long = 0
@ColumnInfo(name = "calories")
var calories: Double = 0.toDouble()
}
个性化食品.kt
@Entity(primaryKeys = arrayOf("food_id","date"))
class PersonalizedFood(@ColumnInfo(name = "quantity") var quantity: Int,
@ColumnInfo(name = "unit") var unit: String,
@ColumnInfo(name = "date") var date: Date){
@ColumnInfo(name = "food_id")
var foodId:Long = 0
}
FoodDao.kt
@Dao
interface FoodDao {
companion object{
const val ID = "id"
const val NAME = "name"
const val PROTEIN = "protein"
const val DESC = "desc"
const val CARBS = "carbs"
const val FAT = "fat"
const val DATE = "date"
const val FOOD_ID = "food_id"
const val ALL_FOOD_LIST = "food"
const val PERSONALISED_FOOD_LIST = "personalised_food"
}
/**
* Returns food details of a food given by food_id
*/
@Query("SELECT * FROM $ALL_FOOD_LIST WHERE $ID=:food_id")
fun getFoodDetails(food_id:Long):Food
/**
* Inserts food items in all_food_list
*/
@Insert
fun addFoodList(list:ArrayList<Food>)
@Insert(onConflict = REPLACE)
fun saveFood(food:PersonalizedFood)
@Query("SELECT * FROM $PERSONALISED_FOOD_LIST WHERE $FOOD_ID=:foodId and $DATE=:date")
fun getFood(foodId:Int, data:Date):PersonalizedFood
@Query("SELECT * FROM $ALL_FOOD_LIST where $ID in (select $FOOD_ID from $PERSONALISED_FOOD_LIST where $DATE = :date)")
fun getFood(date:Date):ArrayList<Food>
}
Converter.kt
class Converter {
companion object{
@TypeConverter
fun fromTimestamp(value: Long?): Date? {
return if (value == null) null else Date(value)
}
@TypeConverter
fun dateToTimestamp(date: Date): Long {
return date.time
}
}
}
食品数据库.kt
@Database(entities = arrayOf(Food::class, PersonalizedFood::class), version = 1)
@TypeConverters(Converter::class)
abstract class FoodDatabase : RoomDatabase(){
abstract fun foodDao():FoodDao
companion object{
private val databaseName = "diet"
var dbInstance:FoodDao? = null
fun getInstance(context:Context):FoodDao?{
if(dbInstance == null)
dbInstance = Room.inMemoryDatabaseBuilder(context, FoodDatabase::class.java).build().foodDao()
return dbInstance;
}
}
}
当我运行以下代码以创建数据库时：
FoodDatabase.getInstance(baseContext)?.getFood(Calendar.getInstance().time)
它给我以下异常：
Caused by: java.lang.RuntimeException: cannot find implementation for com.chandilsachin.diettracker.database.FoodDatabase. FoodDatabase_Impl does not exist at android.arch.persistence.room.Room.getGeneratedImplementation(Room.java:90) at android.arch.persistence.room.RoomDatabase$Builder.build(RoomDatabase.java:340) at com.chandilsachin.diettracker.database.FoodDatabase$Companion.getInstance(FoodDatabase.kt:21) at com.chandilsachin.diettracker.MainActivity$SetUpFoodDatabase.doInBackground(MainActivity.kt:95) at com.chandilsachin.diettracker.MainActivity$SetUpFoodDatabase.doInBackground(MainActivity.kt:77) at android.os.AsyncTask$2.call(AsyncTask.java:295) at java.util.concurrent.FutureTask.run(FutureTask.java:237) at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:234) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588) at java.lang.Thread.run(Thread.java:818)
有人在Kotlin中实现了Room Persistence吗？
编辑：此问题被标记为此问题的重复项。虽然问题陈述相同，但提供的解决方法无法解决我的问题。解决方案表示我必须添加将annotationProcessor替换为kapt "android.arch.persistence.room:compiler:1.0.0-alpha1"依赖项。我进行了这些更改，结果在项目构建时导致gradle错误。
Information: Gradle tasks[:app:assembleDebug] Warning：warning： 来自注释处理器“android.arch.persistence.room.RoomProcessor”的支持源版本“RELEASE_7”小于-source'1.8' Warning：warning：以下选项未被任何处理器识别：“[kapt.kotlin.generated]” /Users/BBI-M1025/Documents/BBI/Workspace_fun/Android/diet-tracker/app/src/main/java/com/chandilsachin/diettracker/database/Food.kt Error：(1, 1)处理注释时发生了一些错误。请参见上面的错误消息。 Error：任务执行失败'：app：kaptDebugKotlin'
编译错误。有关更多详细信息，请参见日志 信息：10秒内构建失败 信息：2个错误 信息：2个警告 信息：请参阅完整的输出
我也附上了我的gradle文件：
apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'
apply plugin: 'kotlin-kapt'
android {
compileSdkVersion 25
buildToolsVersion "25.0.2"
defaultConfig {
applicationId "com.chandilsachin.diettracker"
minSdkVersion 16
targetSdkVersion 25
versionCode 1
versionName "1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
exclude group: 'com.android.support', module: 'support-annotations'
})
compile "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
compile 'com.android.support:appcompat-v7:25.0.1'
compile 'com.android.support.constraint:constraint-layout:1.0.0-alpha8'
compile 'com.android.support:cardview-v7:25.0.1'
compile 'com.android.support:recyclerview-v7:25.0.1'
compile 'com.github.ne1c:rainbowmvp:1.2.1'
compile "org.jetbrains.anko:anko-commons:0.10.0"
/*annotationProcessor "android.arch.persistence.room:compiler:1.0.0-alpha1"
compile "android.arch.lifecycle:extensions:1.0.0-alpha1"
annotationProcessor "android.arch.lifecycle:compiler:1.0.0-alpha1"*/
compile "android.arch.persistence.room:runtime:1.0.0-alpha1"
annotationProcessor "android.arch.persistence.room:compiler:1.0.0-alpha1"
kapt "android.arch.persistence.room:compiler:1.0.0-alpha1"
testCompile 'junit:junit:4.12'
}
repositories {
mavenCentral()
}
有人遇到过这个问题吗？