gradle 同步成功时，Kotlin 多平台无法解析引用

Question

当我编译我的 kotlin 多平台项目时，我在公共模块中使用的东西上得到 Unresolved reference。但是 gradle 同步工作正常。你可以找到我的项目here

详细说明：

1. 我按照Jetbrain to build a mobile multiplatform project 的教程进行操作。一切正常。

2. 然后我在公共模块内部实现了一个ktor客户端来请求一个api（jsonplaceholder）。我添加了所有必需的依赖项，一切似乎都很好。所有引用都已解决，我没有错误。

3. 但是当我使用make Project 编译我的项目时，所有添加到获取ktor 等的依赖项都无法解析。

我想我的项目配置有问题，当我运行./gradlew androidDependencies 时，SharedCode 似乎有问题，因为它有时在命令输出中标记为\--- :SharedCode。

该项目的build.gradle 是：

buildscript {
    ext.kotlin_version = '1.3.71'
    repositories {
        google()
        jcenter()

    }
    dependencies {
        classpath 'com.android.tools.build:gradle:4.0.0-rc01'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        classpath "org.jetbrains.kotlin:kotlin-serialization:$kotlin_version"
    }
}

allprojects {
    repositories {
        google()
        jcenter()

    }
}

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

通用SharedCode 模块的build.gradle.kts 是：

import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinNativeTarget

plugins {
    kotlin("multiplatform")
    kotlin("plugin.serialization")
}

kotlin {
    //select iOS target platform depending on the Xcode environment variables
    val iOSTarget: (String, KotlinNativeTarget.() -> Unit) -> KotlinNativeTarget =
    if (System.getenv("SDK_NAME")?.startsWith("iphoneos") == true)
    ::iosArm64
    else
    ::iosX64

    iOSTarget("ios") {
        binaries {
            framework {
                baseName = "SharedCode"
            }
        }
    }

    jvm("android")

    val serializationVersion = "0.20.0"
    val ktorVersion = "1.3.2"

    sourceSets["commonMain"].dependencies {
        implementation("org.jetbrains.kotlin:kotlin-stdlib-common")
        implementation("org.jetbrains.kotlinx:kotlinx-serialization-runtime-common:$serializationVersion")
        implementation("io.ktor:ktor-client-core:$ktorVersion")
        implementation("io.ktor:ktor-client-json:$ktorVersion")
        implementation("io.ktor:ktor-client-serialization:$ktorVersion")//Kotlinxserializer
    }

    sourceSets["androidMain"].dependencies {
        implementation("org.jetbrains.kotlin:kotlin-stdlib")
    }
}

val packForXcode by tasks.creating(Sync::class) {
    val targetDir = File(buildDir, "xcode-frameworks")

    /// selecting the right configuration for the iOS
    /// framework depending on the environment
    /// variables set by Xcode build
    val mode = System.getenv("CONFIGURATION") ?: "DEBUG"
    val framework = kotlin.targets
            .getByName<KotlinNativeTarget>("ios")
            .binaries.getFramework(mode)
    inputs.property("mode", mode)
    dependsOn(framework.linkTask)

    from({ framework.outputDirectory })
    into(targetDir)

    /// generate a helpful ./gradlew wrapper with embedded Java path
    doLast {
        val gradlew = File(targetDir, "gradlew")
        gradlew.writeText("#!/bin/bash\n"
                + "export 'JAVA_HOME=${System.getProperty("java.home")}'\n"
                + "cd '${rootProject.rootDir}'\n"
                + "./gradlew \$@\n")
        gradlew.setExecutable(true)
    }
}

tasks.getByName("build").dependsOn(packForXcode)

Android 应用的build.gradle 是：

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'

android {
    compileSdkVersion 29
    buildToolsVersion "29.0.3"

    defaultConfig {
        applicationId "com.mpp.mpptest"
        minSdkVersion 16
        targetSdkVersion 29
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }

}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'androidx.appcompat:appcompat:1.1.0'
    implementation 'androidx.core:core-ktx:1.2.0'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'androidx.test.ext:junit:1.1.1'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'

    implementation project(':SharedCode')
}

你知道我做错了什么吗？

我阅读了Building Multiplatform Projects with Gradle，但没有帮助。

我发现的唯一工作项目来自KaMPKit。我已将我的build.gradle(.kts) 文件设置为它们在 KaMPKit 中的状态（请参阅分支 Set_build_gradle_as_KaMPKit），但“未解决的引用”问题仍然存在。

Answer 1

我解决了我的问题。错误是因为我没有声明插件android.lybrary。

即使没有必要修复问题，我还是决定将我的build.gradle 文件切换到kotlin DLS，我重写了所有build.gradle，并对共享模块进行了以下更改：

• 我创建了一个AndroidManifest.xml
• 我添加了com.android.library 插件
• 我添加了一个区块android

最后，共享模块的build.gradle.kts 如下所示：

import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinNativeTarget

plugins {
    kotlin("multiplatform")
    kotlin("plugin.serialization")
    id("kotlinx-serialization")
    id("com.android.library")
}

android {
    compileSdkVersion(29)
    defaultConfig {
        minSdkVersion(Versions.min_sdk)
        targetSdkVersion(Versions.target_sdk)
        versionCode = 1
        versionName = "1.0"
        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
    }
}

kotlin {
    //select iOS target platform depending on the Xcode environment variables
    val iOSTarget: (String, KotlinNativeTarget.() -> Unit) -> KotlinNativeTarget =
    if (System.getenv("SDK_NAME")?.startsWith("iphoneos") == true)
    ::iosArm64
    else
    ::iosX64

    iOSTarget("ios") {
        binaries {
            framework {
                baseName = "SharedCode"
            }
        }
    }

    jvm("android")

    sourceSets["commonMain"].dependencies {
        implementation(kotlin("stdlib-common", Versions.kotlin))
        implementation(Deps.Ktor.commonCore)
        implementation(Deps.Ktor.commonJson)
        implementation(Deps.Coroutines.common)
        implementation(Deps.Ktor.commonSerialization)
    }

    sourceSets["androidMain"].dependencies {
        implementation(kotlin("stdlib", Versions.kotlin))
        implementation(Deps.Coroutines.jdk)
        implementation(Deps.Ktor.androidSerialization)
    }

    sourceSets["iosMain"].dependencies {
        implementation(Deps.Ktor.iosSerialization)
    }
}

val packForXcode by tasks.creating(Sync::class) {
    val targetDir = File(buildDir, "xcode-frameworks")

    /// selecting the right configuration for the iOS
    /// framework depending on the environment
    /// variables set by Xcode build
    val mode = System.getenv("CONFIGURATION") ?: "DEBUG"
    val framework = kotlin.targets
            .getByName<KotlinNativeTarget>("ios")
            .binaries.getFramework(mode)
    inputs.property("mode", mode)
    dependsOn(framework.linkTask)

    from({ framework.outputDirectory })
    into(targetDir)

    /// generate a helpful ./gradlew wrapper with embedded Java path
    doLast {
        val gradlew = File(targetDir, "gradlew")
        gradlew.writeText("#!/bin/bash\n"
                + "export 'JAVA_HOME=${System.getProperty("java.home")}'\n"
                + "cd '${rootProject.rootDir}'\n"
                + "./gradlew \$@\n")
        gradlew.setExecutable(true)
    }
}

tasks.getByName("build").dependsOn(packForXcode)

所有依赖版本号都来自Dependencies.kt 文件（参见KaMPKit）

所有依赖关系现在都已解决。