低版本Kotlin项目集成CameraX遇元数据版本兼容问题求助

我在使用Kotlin 1.3.61的Android项目中集成CameraX，操作步骤如下：

1. 在根build.gradle文件中添加配置：

buildscript {
    repositories {
        google()
        mavenCentral()
        maven { url 'https://jitpack.io' }
        mavenCentral()

    }
    dependencies {
        classpath 'com.android.tools.build:gradle:4.1.3'

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

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

    }
}

2. 在/pes/build.gradle中添加CameraX依赖（因冲突需排除指定组）：

def camerax_version = "1.3.0-alpha07"

implementation("androidx.camera:camera-core:${camerax_version}") {
    exclude group: 'com.google.android.gms'
    exclude group: 'org.jetbrains.kotlin'
}
implementation ("androidx.camera:camera-camera2:${camerax_version}") {
    exclude group: 'com.google.android.gms'
    exclude group: 'org.jetbrains.kotlin'
}
implementation("androidx.camera:camera-lifecycle:${camerax_version}") {
    exclude group: 'com.google.android.gms'
    exclude group: 'org.jetbrains.kotlin'
}
implementation("androidx.camera:camera-video:${camerax_version}") {
    exclude group: 'com.google.android.gms'
    exclude group: 'org.jetbrains.kotlin'
}
implementation("androidx.camera:camera-view:${camerax_version}") {
    exclude group: 'com.google.android.gms'
    exclude group: 'org.jetbrains.kotlin'
}
implementation("androidx.camera:camera-mlkit-vision:${camerax_version}") {
    exclude group: 'com.google.android.gms'
    exclude group: 'org.jetbrains.kotlin'
}
implementation("androidx.camera:camera-extensions:${camerax_version}") {
    exclude group: 'com.google.android.gms'
    exclude group: 'org.jetbrains.kotlin'
}

编译时出现以下错误：

e: C:/Users/AMI/.gradle/caches/transforms-3/64ad5900933e780ce887a006f25ca2fd/transformed/jetified-camera-extensions-1.3.0-alpha07-api.jar!/META-INF/camera-extensions_release.kotlin_module: Module was compiled with an incompatible version of Kotlin. The binary version of its metadata is 1.8.0, expected version is 1.1.16.
e: C:/Users/AMI/.gradle/caches/transforms-3/7dee4547e37043c00f427a0185d4b10d/transformed/jetified-camera-view-1.3.0-alpha07-api.jar!/META-INF/camera-view_release.kotlin_module: Module was compiled with an incompatible version of Kotlin. The binary version of its metadata is 1.8.0, expected version is 1.1.16.
e: C:/Users/AMI/.gradle/caches/transforms-3/8f6f30467f847b66b16817abdf472683/transformed/jetified-camera-video-1.3.0-alpha07-api.jar!/META-INF/camera-video_release.kotlin_module: Module was compiled with an incompatible version of Kotlin. The binary version of its metadata is 1.8.0, expected version is 1.1.16.
e: C:/Users/AMI/.gradle/caches/transforms-3/99bb6fcc1c04207e3b031d7cda6d0f11/transformed/jetified-camera-core-1.3.0-alpha07-api.jar!/META-INF/camera-core_release.kotlin_module: Module was compiled with an incompatible version of Kotlin. The binary version of its metadata is 1.8.0, expected version is 1.1.16.
e: C:/Users/AMI/.gradle/caches/transforms-3/df896c991bee1d4be7efa89fb4fe6913/transformed/jetified-camera-camera2-1.3.0-alpha07-api.jar!/META-INF/camera-camera2_release.kotlin_module: Module was compiled with an incompatible version of Kotlin. The binary version of its metadata is 1.8.0, expected version is 1.1.16.

我的项目buildscript中指定Kotlin版本为1.3.61：

buildscript {
    // Butterknife end of life will not work with JAVA_VERSION_11
    ext.butterknifeVersion = '10.2.3'
    // Can not upgrade to 1.4.21, annotations issues related to not using Java 11
    ext.kotlin_version = '1.3.61'
}

我无法理解为何版本1.3.61高于预期的1.1.16却仍报错，恳请帮忙解释原因。

原因解释 #

你看到的1.1.16并不是Kotlin语言版本，而是Kotlin编译后生成的元数据二进制版本号，它和Kotlin语言版本是两套独立的编号体系：

• Kotlin语言版本是我们日常使用的1.3.61、1.8.x这类编号，对应语言特性的迭代
• 元数据二进制版本是Kotlin编译器用来标识编译后字节码元数据格式的版本号，不同语言版本的编译器会生成对应版本的元数据

你的项目使用的Kotlin 1.3.61编译器只能识别最高到1.3版本的元数据，但你引入的CameraX 1.3.0-alpha07是用Kotlin 1.8编译的，生成的元数据版本为1.8.0。旧版编译器无法解析更高版本的元数据，因此抛出兼容性错误。错误提示里的expected version is 1.1.16是旧版编译器的表述问题，本质是当前编译器不支持处理1.8版本的元数据。

解决方案 #

由于你无法升级Kotlin版本（受限于ButterKnife 10.2.3不支持Java 11），只能降级CameraX到一个与Kotlin 1.3兼容的版本。CameraX 1.0.x稳定版是用旧版Kotlin编译的，可兼容你的项目环境：

修改模块build.gradle中的CameraX版本配置：

def camerax_version = "1.0.2"

implementation "androidx.camera:camera-core:${camerax_version}"
implementation "androidx.camera:camera-camera2:${camerax_version}"
implementation "androidx.camera:camera-lifecycle:${camerax_version}"
implementation "androidx.camera:camera-view:${camerax_version}"
// 若不需要video、mlkit、extensions模块可省略对应依赖

同时可以去掉排除org.jetbrains.kotlin组的配置，因为旧版CameraX依赖的Kotlin版本与你的项目兼容，不会产生冲突。

内容的提问来源于stack exchange，提问作者Ameen Izhac