2019-10-25 更新说明: 这篇文章因为发布时效的原因, 当时还没有 `$ flutter build aar` 这个命令
所以本人并没有实测两个东西的优劣性

xcode
android sdk
gradle
android studio
flutter sdk
docker # 这个

cd flutter_module
flutter build apk

tree .android/Flutter/build/outputs
.android/Flutter/build/outputs
├── aar
│   └── flutter-release.aar
└── logs
    └── manifest-merger-release-report.txt

docker run --name test_nexus -d -p 8099:8081 -v /Volumes/Evo512/docker/nexus/nexus-data:/nexus-data sonatype/nexus3

version: ‘2‘

services:
  my-nexus:
    image: sonatype/nexus3
    ports:
      - 8099:8081
    networks:
      - nexus-net
    volumes:
      - /Volumes/Evo512/docker/nexus/nexus-data:/nexus-data

networks:
  nexus-net:
    driver: bridge

docker-compose -d up

apply plugin: ‘maven‘

def GROUP = ‘top.kikt.flutter_lib‘
def ARTIFACT_ID = ‘module_example‘
def VERSION_NAME = "1.0.0"

def SNAPSHOT_REPOSITORY_URL = ‘http://localhost:8099/repository/maven-snapshots/‘
def RELEASE_REPOSITORY_URL = ‘http://localhost:8099/repository/maven-releases/‘
def REPOSITORY_URL = VERSION_NAME.toUpperCase().endsWith("-SNAPSHOT") ? SNAPSHOT_REPOSITORY_URL : RELEASE_REPOSITORY_URL


def NEXUS_USERNAME = ‘admin‘
def NEXUS_PASSWORD = ‘admin123‘

afterEvaluate { project ->
    uploadArchives {
        repositories {
            mavenDeployer {
                pom.groupId = GROUP
                pom.artifactId = ARTIFACT_ID
                pom.version = VERSION_NAME
                repository(url: REPOSITORY_URL) {
                    authentication(userName: NEXUS_USERNAME, password: NEXUS_PASSWORD)
                }
            }
        }
    }
    task androidJavadocs(type: Javadoc) {
        source = android.sourceSets.main.java.srcDirs
        classpath += project.files(android.getBootClasspath().join(File.pathSeparator))
    }
    task androidJavadocsJar(type: Jar, dependsOn: androidJavadocs) {
        classifier = ‘javadoc‘
        from androidJavadocs.destinationDir
    }
    task androidSourcesJar(type: Jar) {
        classifier = ‘sources‘
        from android.sourceSets.main.java.sourceFiles
    }

    //解决 JavaDoc 中文注释生成失败的问题
    tasks.withType(Javadoc) {
        options.addStringOption(‘Xdoclint:none‘, ‘-quiet‘)
        options.addStringOption(‘encoding‘, ‘UTF-8‘)
        options.addStringOption(‘charSet‘, ‘UTF-8‘)
    }
    artifacts {
        archives androidSourcesJar
        archives androidJavadocsJar
    }
}

android{
    /// ....
}

apply from: "${rootDir.path}/update_aar.gradle"

11:58:23: Executing task ‘uploadArchives‘...

Executing tasks: [uploadArchives]


FAILURE: Build failed with an exception.

* Where:
Settings file ‘/Volumes/Evo512/code/flutter/add_to_exists_android/flutter_module/.android/settings.gradle‘ line: 7

* What went wrong:
A problem occurred evaluating settings ‘android_generated‘.
> /Volumes/Evo512/code/flutter/add_to_exists_android/flutter_module/.android/Flutter/include_flutter.groovy (/Volumes/Evo512/code/flutter/add_to_exists_android/flutter_module/.android/Flutter/include_flutter.groovy)

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 0s
11:58:23: Task execution finished ‘uploadArchives‘.

// Generated file. Do not edit.
include ‘:app‘

rootProject.name = ‘android_generated‘
setBinding(new Binding([gradle: this]))
//evaluate(new File(‘include_flutter.groovy‘))
evaluate(new File("$rootDir.path/include_flutter.groovy"))

allprojects {
    repositories {
        google()
        jcenter()
        maven {
            url ‘http://localhost:8099/repository/maven-releases/‘
        }
    }
}

dependencies {
    // ...
    implementation ‘top.kikt.flutter_lib:module_example:1.0.0‘
}

package top.kikit.androidhost;

import android.os.Bundle;

import io.flutter.app.FlutterActivity;
import io.flutter.plugins.GeneratedPluginRegistrant;

/// create 2019-06-14 by cai

public class MyFlutterActivity extends FlutterActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        GeneratedPluginRegistrant.registerWith(this);
    }
}

<application>
    <activity android:name=".MyFlutterActivity" />
</application>

package top.kikit.androidhost;

import android.content.Intent;
import android.os.Bundle;

import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Flutter.startInitialization(this.getApplicationContext());
        Intent intent = new Intent(this, MyFlutterActivity.class);
        startActivity(intent);
    }
}

android{
    compileOptions {
        sourceCompatibility 1.8
        targetCompatibility 1.8
    }
}

dependencies:
  shared_preferences: ^0.5.3+1

ERROR: Unable to resolve dependency for ‘:app@debug/compileClasspath‘: Could not resolve io.flutter.plugins.sharedpreferences:shared_preferences:1.0-SNAPSHOT.
Show Details
Affected Modules: app


ERROR: Unable to resolve dependency for ‘:app@debugAndroidTest/compileClasspath‘: Could not resolve io.flutter.plugins.sharedpreferences:shared_preferences:1.0-SNAPSHOT.
Show Details
Affected Modules: app


ERROR: Unable to resolve dependency for ‘:app@debugUnitTest/compileClasspath‘: Could not resolve io.flutter.plugins.sharedpreferences:shared_preferences:1.0-SNAPSHOT.
Show Details
Affected Modules: app

<project xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>top.kikt.flutter_lib</groupId>
    <artifactId>module_example</artifactId>
    <version>1.0.2</version>
    <packaging>aar</packaging>
    <dependencies>
        <dependency>
            <groupId>io.flutter.plugins.sharedpreferences</groupId>
            <artifactId>shared_preferences</artifactId>
            <version>1.0-SNAPSHOT</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>com.android.support</groupId>
            <artifactId>support-v13</artifactId>
            <version>27.1.1</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>com.android.support</groupId>
            <artifactId>support-annotations</artifactId>
            <version>27.1.1</version>
            <scope>compile</scope>
        </dependency>
    </dependencies>
</project>

import ‘dart:io‘;

var outputDir = Directory("../output");
var targetDir = Directory("../../flutter-aar");

Future main() async {
  List<AAR> list = [];

  outputDir.deleteSync(recursive: true);
  outputDir.createSync(recursive: true);
  var file = File("../.flutter-plugins");
  var plugins = file.readAsLinesSync();
  for (var value in plugins) {
    if (value.trim().isEmpty) {
      continue;
    }
    var splitArr = value.split("=");
    var name = splitArr[0];
    var path = splitArr[1];

    var aar = handlePlugin(name, path);
    list.add(aar);
  }

  var aar = await handleFlutter();
  list.add(aar);

  handleAAR(list);
}

void handleAAR(List<AAR> list) {
  targetDir.deleteSync(recursive: true);
  targetDir.createSync();
  list.forEach((aar) {
    var targetPath = "${targetDir.path}/${aar.aarName}";
    var targetFile = aar.file.copySync(targetPath);
    print(
        ‘\ncopy "${aar.file.absolute.path}" to "${targetFile.absolute.path}"‘);
  });
}

AAR handlePlugin(String name, String path) {
  var result = Process.runSync("./gradlew", ["$name:assRel"],
      workingDirectory: "../.android");
  print(result.stdout);

  var aarFile = File("$path/android/build/outputs/aar/$name-release.aar");
  var aarName = aarFile.path.split("/").last;
  var pathName = "${outputDir.path}/$aarName";
  var targetFile = aarFile.copySync(pathName);
  return AAR()
    ..file = targetFile
    ..aarName = aarName;
}

Future<AAR> handleFlutter() async {
  var processResult = await Process