Flutter module upload aar to maven

flutter_aar_upload.gradle

// This script is used to initialize the build in a module or plugin project.
// During this phase, the script applies the Maven plugin and configures the
// destination of the local repository.
// The local repository will contain the AAR and POM files.

void configureProject(Project project, String mavenUrl, String mavenUser, String mavenPwd, String version) {
  if (!project.hasProperty("android")) {
    throw new GradleException("Android property not found.")
  }
  if (!project.android.hasProperty("libraryVariants")) {
    throw new GradleException("Can't generate AAR on a non Android library project.")
  }

  project.apply plugin: "maven"

  // Snapshot versions include the timestamp in the artifact name.
  // Therefore, remove the snapshot part, so new runs of `flutter build aar` overrides existing artifacts.
  // This version isn't relevant in Flutter since the pub version is used
  // to resolve dependencies.

  project.version = version
  if (mavenUrl.startsWith("file:")) {
    //本地路径时，原逻辑
    project.version = project.version.replace("-SNAPSHOT", "")
  }


  project.android.libraryVariants.all { variant ->
    addAarTask(project, variant)
  }

  project.uploadArchives {
    repositories {
      mavenDeployer {
        repository(url: mavenUrl) {
          if (mavenUser != null) {
            authentication(userName: mavenUser, password: mavenPwd)
          }
        }
        //默认本地路径：
        //repository(url: "file://${outputDir}/outputs/repo")
      }
    }
  }
  if (!project.property("is-plugin").toBoolean()) {
    return
  }

  if (project.hasProperty('localEngineOut')) {
    // TODO(egarciad): Support local engine.
    // This most likely requires refactoring `flutter.gradle`, so the logic can be reused.
    throw new GradleException(
        "Local engine isn't supported when building the plugins as AAR. " +
            "See: https://github.com/flutter/flutter/issues/40866")
  }

  // This is a Flutter plugin project. Plugin projects don't apply the Flutter Gradle plugin,
  // as a result, add the dependency on the embedding.
  project.repositories {
    maven {
      url "https://storage.googleapis.com/download.flutter.io"
    }
  }
  String engineVersion = flutterEngineVersion()
  project.dependencies {
    // Add the embedding dependency.
    //使用api方式打入aar
    compileOnly("io.flutter:flutter_embedding_release:1.0.0-$engineVersion") {
      //    api("io.flutter:flutter_embedding_release:1.0.0-$engineVersion") {
      // We only need to expose io.flutter.plugin.*
      // No need for the embedding transitive dependencies.
      transitive = true
    }
  }
}

void configurePlugin(Project project, String outputDir, String mavenUser, String mavenPwd) {
  if (!project.hasProperty("android")) {
    // A plugin doesn't support the Android platform when this property isn't defined in the plugin.
    return
  }
  //flutter plugin 版本号
  File pubspecFile = project.file("../pubspec.yaml")
  String versionLine = pubspecFile.readLines().find { line->
    line.startsWith("version:")
  }
  def pluginVersion = versionLine.split(":")[1].trim()
  println("configurePlugin: " + project.toString() + " v" + pluginVersion)
  configureProject(project, outputDir, mavenUser, mavenPwd, pluginVersion)
}

void addAarTask(Project project, variant) {
  String variantName = variant.name.capitalize()
  String taskName = "assembleAar$variantName"
  project.tasks.create(name: taskName) {
    // This check is required to be able to configure the archives before `uploadArchives` runs.
    if (!project.gradle.startParameter.taskNames.contains(taskName)) {
      return
    }
    project.uploadArchives.repositories.mavenDeployer {
      pom {
        artifactId = "${project.name}_${variant.name.toLowerCase()}"
      }
    }
    overrideDefaultPublishConfig(project, variant)
    // Generate the Maven artifacts.
    finalizedBy "uploadArchives"
  }
}

// This method mimics the logic in AGP when `android.defaultPublishConfig` is set in `build.gradle`:
// https://android.googlesource.com/platform/tools/base/+/studio-master-dev/build-system/gradle-core/src/main/java/com/android/build/gradle/internal/variant/VariantHelper.java
//
// Unfortunately, `android.defaultPublishConfig` cannot be overriden at this point since
// AGP already run this code.
void overrideDefaultPublishConfig(Project project, variant) {
  String variantName = variant.name.capitalize()
  Task bundle = project.tasks.findByName("bundle${variantName}Aar")
  // gradle:3.2.0
  if (bundle == null) {
    bundle = project.tasks.findByName("bundle${variantName}") // gradle:3.1.0
  }
  if (bundle == null) {
    throw new GradleException("Can't generate AAR for variant ${variantName}.")
  }
  // Clear the current archive artifacts since the artifacts are based on `android.defaultPublishConfig`.
  project.configurations["archives"].artifacts.clear()
  // Add the artifact that will be published.
  project.artifacts.add("archives", bundle)

  def scopeMappings = project.uploadArchives.repositories.mavenDeployer.pom.scopeMappings
  // Clear the scope mappings added by AGP since they are based on the current `android.defaultPublishConfig`.
  scopeMappings.mappings.clear()
  // Add the new mappings.
  for (Configuration configuration : flattenConfiguration(variant.runtimeConfiguration)) {
    scopeMappings.addMapping(/* priority = */ 300, configuration, "compile")
  }
}

Set<Configuration> flattenConfiguration(Configuration configuration) {
  Set<Configuration> configs = [configuration]
  for (Configuration extend : configuration.extendsFrom) {
    configs.addAll(flattenConfiguration(extend))
  }
  return configs
}

projectsEvaluated {
  assert rootProject.hasProperty("is-plugin")
  if (rootProject.property("is-plugin").toBoolean()) {
    assert rootProject.hasProperty("maven-url")
    // In plugin projects, the root project is the plugin.
    configureProject(rootProject, rootProject.property("maven-url"),
        rootProject.property("maven-user"), rootProject.property("maven-pwd"),
        project.property("buildNumber")
    )
    return
  }
  // The module project is the `:flutter` subproject.
  Project moduleProject = rootProject.subprojects.find { it.name == "flutter" }

  assert moduleProject != null
  assert moduleProject.hasProperty("maven-url")
  configureProject(moduleProject, moduleProject.property("maven-url"),
      moduleProject.property("maven-user"), moduleProject.property("maven-pwd"),
      moduleProject.property("buildNumber")
  )

  // Gets the plugin subprojects.
  Set<Project> modulePlugins = rootProject.subprojects.findAll {
    it.name != "flutter" && it.name != "app"
  }
  // When a module is built as a Maven artifacts, plugins must also be built this way
  // because the module POM's file will include a dependency on the plugin Maven artifact.
  // This is due to the Android Gradle Plugin expecting all library subprojects to be published
  // as Maven artifacts.
  String mavenUrl = moduleProject.property("maven-url")
  String version = moduleProject.property("buildNumber")

  println("Version: $version")
  println("MavenUrl: " + mavenUrl)

  //输出 配置
  String buildMode = moduleProject.gradle.startParameter
      .taskNames.find { it.startsWith("assembleAar") }.substring(11)
  println("BuildMode: $buildMode")

  println("================================================================================")
  //配置插件
  modulePlugins.each { pluginProject ->
    configurePlugin(pluginProject, mavenUrl,
        moduleProject.property("maven-user"), moduleProject.property("maven-pwd"))
    moduleProject.android.libraryVariants.all { variant ->
      // Configure the `assembleAar<variantName>` task for each plugin's projects and make
      // the module's equivalent task depend on the plugin's task.
      String variantName = variant.name.capitalize()
      moduleProject.tasks.findByPath("assembleAar$variantName")
          .dependsOn(pluginProject.tasks.findByPath("assembleAar$variantName"))
    }
  }
  //结束
  println("================================================================================")

  String mUrl = mavenUrl
  if (mavenUrl.startsWith("file://")) {
    mUrl = mavenUrl.substring(7)
  }

  String groupId = moduleProject.group

  println("""
1. 添加maven地址
repositories {
  maven {
      url '${mUrl}'
  }
  maven {
      url 'https://storage.googleapis.com/download.flutter.io'
  }
}
2. 添加依赖

dependencies {
  implementation '${groupId}:flutter_${buildMode.toLowerCase()}:${version}'
}
""")
}

感谢回复和提供思路，我基于最新的 flutter 3.3.9 stable 版的 aar_init_script.gradle 文件做了修改，实测可以上传到远程私有仓库，如果有遇到这个问题的朋友可以参考下。
flutter_aar_build_upload.gradle

@wqandroid make sure you're passing is-plugin as parameter when you run your script

感谢两位 @Vove7 @xiejianchao提供的Flutter Version: 2.x and 3.x，我已经成功使用 3.x flutter_aar_build_upload.gradle上传到本地的nexus了。