Gradle Kotlin DSL子项目Java配置报错，如何统一设置JDK17？

我希望将所有子项目的Java版本统一设置为17，主项目的build.gradle.kts配置如下：

group = "org.example"
version = "1.0-SNAPSHOT"

subprojects {
    apply(plugin = "java")
    repositories {
        mavenCentral()
        mavenLocal()
    }

    configure<JavaCompile> {
        targetCompatibility = JavaVersion.VERSION_17.toString()
        sourceCompatibility = JavaVersion.VERSION_17.toString()
    }

    java {
        toolchain {
            languageVersion.set(JavaLanguageVersion.of(17))
        }
    }
}

执行gradle clean build时出现以下错误：

% gradle clean build

Configure project :
e: file:///Users/rnatarajan/Documents/Coding/others/org-example/build.gradle.kts:28:5: Expression 'java' cannot be invoked as a function. The function 'invoke()' is not found
e: file:///Users/rnatarajan/Documents/Coding/others/org-example/build.gradle.kts:28:5: Unresolved reference. None of the following candidates is applicable because of receiver type mismatch:
public val PluginDependenciesSpec.java: PluginDependencySpec defined in org.gradle.kotlin.dsl
e: file:///Users/rnatarajan/Documents/Coding/others/org-example/build.gradle.kts:29:9: Unresolved reference: toolchain
e: file:///Users/rnatarajan/Documents/Coding/others/org-example/build.gradle.kts:30:13: Unresolved reference: languageVersion

FAILURE: Build failed with an exception.

错误原因 #

原配置中java {}是Gradle Groovy DSL的写法，在Kotlin DSL中不支持直接这样调用，需要通过JavaPluginExtension扩展来配置Java工具链。

修复后的配置 #

推荐两种修复方式，第二种更简洁：

方式一：保留兼容性配置 + 正确配置工具链

group = "org.example"
version = "1.0-SNAPSHOT"

subprojects {
    apply(plugin = "java")
    repositories {
        mavenCentral()
        mavenLocal()
    }

    tasks.withType<JavaCompile> {
        sourceCompatibility = JavaVersion.VERSION_17.toString()
        targetCompatibility = JavaVersion.VERSION_17.toString()
    }

    // 替换原有的java{}块，通过JavaPluginExtension配置工具链
    configure<JavaPluginExtension> {
        toolchain {
            languageVersion.set(JavaLanguageVersion.of(17))
        }
    }
}

方式二：仅用工具链配置（自动同步兼容性版本）

配置Java工具链后，Gradle会自动将sourceCompatibility和targetCompatibility同步为工具链指定的版本，因此可以去掉单独的编译兼容性配置：

group = "org.example"
version = "1.0-SNAPSHOT"

subprojects {
    apply(plugin = "java")
    repositories {
        mavenCentral()
        mavenLocal()
    }

    configure<JavaPluginExtension> {
        toolchain {
            languageVersion.set(JavaLanguageVersion.of(17))
        }
    }
}

验证 #

修改配置后，重新执行gradle clean build即可正常完成编译，所有子项目都会使用Java 17版本进行构建。

内容的提问来源于stack exchange，提问作者user51