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Kotlin中Room Persistence库的实现（Gradle错误）

androidkotlin
5

我正在使用Kotlin实现Room持久性库来实现我的数据库。

同样的问题在Android Room Persistences library and Kotlin线程中被问到，应用这些解决方案导致了不同的gradle错误：

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()
}

PersonalizedFood.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
        }
    }
}

FoodDatabase.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;
        }
    }
}

当我运行以下代码来创建数据库时：

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中实现了房间持久性吗？

编辑

我之前关于同一主题的问题被标记为this的重复。虽然问题陈述相同，但给出的解决方案并不能解决我的问题。解决方案说我必须将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: Supported source version 'RELEASE_7' from annotation processor 'android.arch.persistence.room.RoomProcessor' less than -source '1.8'
Warning:warning: The following options were not recognized by any processor: '[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) Some error(s) occurred while processing annotations. Please see the error messages above.
Error:Execution failed for task ':app:kaptDebugKotlin'.
> Compilation error. See log for more details
Information:BUILD FAILED in 10s
Information:2 errors
Information:2 warnings
Information:See complete output in console

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？

2
版主，请在标记为重复之前检查问题陈述。 - Sachin Chandil
您可以跟踪一些问题 https://youtrack.jetbrains.com/issues/KT，如果您认为相关，也可以提交一些错误报告。 - Raghunandan
请检查以下两个事项：
  1. Kotlin到JVM目标版本（文件>设置> Kotlin编译器）
  2. 项目JDK版本 文件>项目结构>“JDK位置”以查看为您的项目设置的JDK；然后进入设置的路径，导航到“bin”，并键入“java-version”。
 - Nicola De Fiorenze
@NicolaDeFiorenze JVM 目标版本为 1.6，Java 版本为 "1.8.0_91"。 - Sachin Chandil
请尝试更新JDK，可能升级到v1.8.0_121。我尝试将Kotlin设置为JVM目标为1.6和1.8，但无法复现您的错误。Java版本似乎是唯一的区别。 - Nicola De Fiorenze
@NicolaDeFiorenze 的问题不在于 JDK 或 Kotlin 版本，而是一些 Gradle 配置。 - Sachin Chandil
2个回答
12

在这个问题上我绕了一段时间，最终找到了解决方案。

由于目前没有官方的教程、博客等能够帮助解决这个问题，所以很难。我必须对 gradle 插件和依赖项的所有组合进行多次尝试才能确定 gradle 配置有问题。

现在来看看解决方案：

我必须从 build.gradle(:module) 文件中删除 apply plugin: 'kotlin-kapt'，并将 annotationProcessor "android.arch.persistence.room:compiler:1.0.0-alpha1" 替换为 kapt "android.arch.persistence.room:compiler:1.0.0-alpha1"。

这是 gradle 配置，可以成功编译代码。

但还有更多需要检查的事情。您必须初始化您的 @Entity class 属性，与 Room Persistence lib doc 中给出的 Java 不同。虽然有 getter/setter，但是没有提到需要创建一个带初始化参数的构造函数。因此，我不得不改变我的 @Entity 类：

@Entity(tableName = "all_food_list")
class Food (@ColumnInfo(name = "food_name") var foodName: String = "",
            @ColumnInfo(name = "food_desc") var foodDesc: String = "",
            @ColumnInfo(name = "protein") var protein: Double = 0.0,
            @ColumnInfo(name = "carbs") var carbs: Double = 0.0,
            @ColumnInfo(name = "fat") var fat: Double = 0.0,
            @ColumnInfo(name = "calories") var calories: Double = 0.0)
{
    @ColumnInfo(name = "id")
    @PrimaryKey(autoGenerate = true)
    var id: Long = 0
}

现在来说TypeConverts，与Java不同的是，你需要创建普通函数而不是静态函数（companion object）:

class Converters{

        @TypeConverter
        fun fromTimestamp(value: String): Calendar {
            val arr = value.split("-")
            val cal = Calendar.getInstance()
            cal.set(arr[0].toInt(), arr[1].toInt(), arr[2].toInt())
            return cal
        }

        @TypeConverter
        fun dateToTimestamp(date: Calendar): String {
            return "${date.get(Calendar.DATE)}-${date.get(Calendar.MONTH)+1}-${date.get(Calendar.YEAR)}"
        }

}

我也将添加build.gradle文件以使其更加清晰：

build.gradle(:project)

buildscript {
    ext.kotlin_version = '1.1.2-4'
    ext.gradle_version_stable = '2.3.2'
    ext.gradle_version_preview = '3.0.0-alpha1'
    ext.anko_version = '0.10.0'
    repositories {
        maven { url 'https://maven.google.com' }
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.0.0-alpha1'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        maven { url 'https://maven.google.com' }
        jcenter()
        maven { url "https://jitpack.io" }
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

build.gradle(:module)

：构建Gradle项目的配置文件，其中":module"表示该配置文件属于哪个子模块（如果有）。
apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'

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"
    ...
    ...
    // room persistence dependency 
    compile "android.arch.persistence.room:runtime:1.0.0-alpha1"
    kapt "android.arch.persistence.room:compiler:1.0.0-alpha1"

    testCompile 'junit:junit:4.12'
}
repositories {
    mavenCentral()
}

我认为这就是我所做的一切，让我的代码工作。

希望这也能帮助其他人。

1
你也可以将你的转换器保留为 object，但在方法上加上 @JvmStatic。这样生成的方法实际上将是静态的，Room 插件也会很高兴。 - BoD
将默认值添加到属性可以解决我的问题。这是一个糟糕的解决方案。我甚至认为这是一个错误。 - murt
@murt 这不是一个 bug，因为实体类不需要有参数化构造函数，但必须有默认值。 - Sachin Chandil
1
好的，但是在Java中字段可能没有被初始化，那么为什么var属性必须要呢？ - murt
0

在 build.gradle 文件中的 dependencies 之前，加入以下内容即可 :D 

    kapt {
          generateStubs = true
    }
这并没有解决Impl文件未生成的问题 - 至少对我来说没有。 - AgentKnopf
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