Flutter 混合工程体系 一文中,阐述了Flutter 三种开发模式,在实际业务中搭建持续集成时,我们更希望发本地开发使用混合模式,持续集成使用解耦模式, 主要是解决以下两个问题:

  1. 混合模式:开发调试方便,包括热更新, Native 与 Flutter 开发源码断点调试
  2. 解耦模式:不侵入 Android /iOS Native工程,不对 Flutter 环境产生依赖,可以单独独立构建打包

我们这里重点阐述 解耦模式,要对 Android 与 Flutter 进行解藕,就需要分析混合模式最终生成的 APK 内容长啥样和 Flutter 构建脚本。

Android Flutter APK 文件结构分析

我们通过 Android Studio 菜单 Build -> Analyze APK 选择构建好的 Release APK 包,可以看到如下内容:

image.png

通过上面 APK 结构,我们会发现Flutter 项目比普通的Android 项目多了如下几个文件:

以下文件说明参考 https://blog.csdn.net/weixin_34001430/article/details/87942062

  • lib/armeabi-v7a/libflutter.so - Flutter 引擎
  • isolate_snapshot_instr - 应用程序指令段
  • isolate_snapshot_data - 应用程序数据段
  • vm_snapshot_instr - DartVM 指令段
  • vm_snapshot_data - DartVM 数据段
  • flutter_assets - 应用程序静态资源文件与配置

Flutter 项目 Gradle 构建脚本分析

在 Flutter Android 工程里面,我们在 build.gradle 文件里面会看到 Flutter gradle 构建脚本:

apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"

进入 flutter.gradle 里面,我们会看到相关 flutter 的打包构建流程,主要包括三个部分:

  • apply 方法:flutter 引擎平台架构(arm, x86) 库处理

image.png

  • buildBundle 方法:flutter aot 和 bundle 编译处理,也就是上面所说的 snapshot 相关flutter 构建产物文件

image.png

运行以后会发现其实执行的如下两条命令:

// Debug
flutter build bundle  --debug

// release
flutter build aot  --release
  • *getAssets: *构建产物处理, 把 flutter snapshot 构建产物复制到 assets 目录,刚好与上面 APK 文件结构分析对应起来了。

image.png

Android Flutter 解耦处理

通过上面的 APK 文件和 Gradle 构建脚本分析,我们很清楚的知道了整个 Flutter 构建打包以及与Native 合并的过程, 接下来我们来进行 Android Native 工程 和 Flutter Module 工程解耦处理。

Android Native 项目依赖和构建配置处理

  • 移除 Android Native 项目 ${root}/setting.gradle 对 flutter 构建的脚本的依赖
// 需要移除
evaluate(new File(
  settingsDir.parentFile,
  'happyflutter/.android/include_flutter.groovy'
))
  • 移除 Android Native 项目 ${root}/app/build.gradle 对 flutter 引擎库的依赖
dependencies {
  implementation project(':flutter') // 需要删除
}
  • Android Native 项目 ${root}/app/build.gradle 添加对 libs 文件夹的 .jar .aar 库

dependencies {
    // implementation project(':flutter')
    implementation fileTree(dir: 'libs', include: ['*.jar', '*.aar'])
}

Flutter Mobule 打包为独立的 .aar 文件 gradle 脚本编写

  • 修改 Flutter Module 项目构建类型 com.android.applicationcom.android.library
  • 简化 *$flutterRoot/packages/flutter_tools/gradle/flutter.gradle *构建逻辑
  • ${root}/android/app/build.gradle 完整内容如下
    import java.nio.file.Path
    import java.nio.file.Paths
    

apply plugin: ‘com.android.library’

android {
compileSdkVersion 28

compileOptions {
    sourceCompatibility 1.8
    targetCompatibility 1.8
}

defaultConfig {
    minSdkVersion 16
    targetSdkVersion 28
    versionCode 1
    versionName "1.0"
    testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"

// ndk {
// abiFilters ‘x86’, ‘x86_64’, ‘armeabi-v7a’, ‘armeabi-v8a’, ‘armeabi’
// }
}

buildTypes {
    profile {
        initWith debug
    }
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    }
}
sourceSets {
    main {
        jniLibs.srcDirs "jniLibs"
    }
}

}

// ${project.projectDir.getAbsolutePath()}
Properties properties = new Properties()
properties.load(project.rootProject.file(‘local.properties’).newDataInputStream())
String targetArch = ‘arm’
if (project.hasProperty(‘target-platform’) && project.property(‘target-platform’) == ‘android-arm64’) {
targetArch = ‘arm64’
}
// def isDebug = gradle.startParameter.taskNames.contains(“assembleDebug”)
// def platform = isDebug ? “android-x86” : “android-${targetArch}-release”
def flutterRoot = properties.getProperty(‘flutter.sdk’)
def flutterJarPath = “${flutterRoot}/bin/cache/artifacts/engine/android-${targetArch}-release/flutter.jar”

Path baseEnginePath = Paths.get(flutterRoot, “bin”, “cache”, “artifacts”, “engine”)
File debugFlutterJar = baseEnginePath.resolve(“android-${targetArch}”).resolve(“flutter.jar”).toFile()
File releaseFlutterJar = baseEnginePath.resolve(“android-${targetArch}-release”).resolve(“flutter.jar”).toFile()
File flutterX86Jar = baseEnginePath.resolve(“android-x86”).resolve(“flutter.jar”).toFile()
File flutterX64Jar = baseEnginePath.resolve(“android-x64”).resolve(“flutter.jar”).toFile()

//println flutterX86Jar.length()
//println flutterX86Jar.parentFile

Task flutterX86JarTask = project.tasks.create(“FlutterX86Jar”, Jar) {
from(“${flutterRoot}/bin/cache/artifacts/engine/android-x86/libflutter.so”) {
into “lib/x86”
}
from(“${flutterRoot}/bin/cache/artifacts/engine/android-x64/libflutter.so”) {
into “lib/x86_64”
}
}

project.android.buildTypes.each {
addFlutterJarImplementationDependency(project, flutterX86JarTask, debugFlutterJar, releaseFlutterJar, flutterX86Jar, flutterX64Jar)
}
project.android.buildTypes.whenObjectAdded {
addFlutterJarImplementationDependency(project, flutterX86JarTask, debugFlutterJar, releaseFlutterJar, flutterX86Jar, flutterX64Jar)
}

private void addFlutterJarImplementationDependency(Project project, Task flutterX86JarTask, File debugFlutterJar, File releaseFlutterJar, File flutterX86Jar, File flutterX64Jar) {
def isDebug = gradle.startParameter.taskNames.contains(“assembleDebug”)
project.dependencies {
String configuration
if (project.getConfigurations().findByName(“implementation”)) {
configuration = “implementation”
} else {
configuration = “compile”
}
add(configuration, project.files {
if (isDebug) {
[flutterX86JarTask, releaseFlutterJar]
} else {
releaseFlutterJar
}
})
}
}

private Properties readPropertiesIfExist(File propertiesFile) {
Properties result = new Properties()
if (propertiesFile.exists()) {
propertiesFile.withReader(‘UTF-8’) { reader -> result.load(reader) }
}
return result
}

afterEvaluate {
android.libraryVariants.all { def variant ->
// println variant.mergeAssets.outputDir
// println variant.buildType.debuggable

    def flutterAsset = files("../../build")
    def flutterAOT = files("../../build/aot")
    def mergeFlutterAssets = project.tasks.create(name: "mergeFlutterAssets${variant.name.capitalize()}", type: Copy) {
        // dependsOn copySharedFlutterAssetsTask
        dependsOn variant.mergeAssets

        from (flutterAsset){
            include "flutter_assets/**"
            exclude{
                 details ->details.file.name.contains('isolate_snapshot_data') ||
                         details.file.name.contains('vm_snapshot_data') ||
                         details.file.name.contains('kernel_blob.bin')
            }
        }

        from (flutterAOT){
            include "vm_snapshot_data"
            include "vm_snapshot_instr"
            include "isolate_snapshot_data"
            include "isolate_snapshot_instr"
        }

        into variant.mergeAssets.outputDir

    }
    variant.outputs[0].processResources.dependsOn(mergeFlutterAssets)
}

}

dependencies {
implementation fileTree(dir: ‘libs’, include: [‘*.jar’])
implementation ‘com.android.support:appcompat-v7:28.0.0-alpha1’
testImplementation ‘junit:junit:4.12’
androidTestImplementation ‘com.android.support.test:runner:1.0.2’
androidTestImplementation ‘com.android.support.test.espresso:espresso-core:3.0.2’
}




### 编写 Flutter 插件和 Flutter Module 项目自动化 shell 脚本构建

- 项目 AOT 和 Bundle 编译 ${root}/script/project.sh

```bash
#!/bin/bash
root=`pwd`

. "${root}/script/util.sh"

green "--root: ${root}, build mode: ${build},  run mode: ${run}"

green "--start flutter aot and bundle build"

flutter clean

if [[ $build = "debug" ]]
then
   # green ">>flutter build aot --debug && flutter build bundle --debug"
   # android-arm does not support AOT compilation
   # flutter build aot --debug
   # flutter build bundle --debug
   green "--android-arm does not support AOT compilation, use release build aot"
   yellow ">>flutter build aot --release && flutter build bundle --debug"
   # android-arm does not support AOT compilation
   flutter build aot --release
   flutter build bundle --debug
   if [[ $build = 'debug' ]] && [[ $run = 'simulator' ]]; then
      cp -f "${root}/build/flutter_assets/vm_snapshot_data"       "${root}/build/aot/vm_snapshot_data"
      cp -f "${root}/build/flutter_assets/isolate_snapshot_data"  "${root}/build/aot/isolate_snapshot_data"
      green ">>when debug and simulator mode, copy snapshot successfully!"
   fi
   yellow ">>./gradlew assembleDebug"
   cd android && ./gradlew clean && ./gradlew assembleDebug
   cd ..
else
   yellow ">>flutter build aot --release && flutter build bundle --release"
   flutter build aot --release
   flutter build bundle --release
   yellow ">>./gradlew assembleRelease"
   cd android && ./gradlew clean && ./gradlew assembleRelease
   cd ..
fi

green "--flutter arr file[ ${root}/android/app/build/outputs/aar/app-${build}.aar ] build successfully!"


cp -f "${root}/android/app/build/outputs/aar/app-${build}.aar"  "${root}/publish/${build}"
  • Flutter 插件 .aar 文件生成和处理 ${root}/script/plugin.sh

这里是直接从 Flutter 插件编译的缓存目录拷贝 .arr 文件。目前需要自己手动在 Flutter Module 项目目录下执行 flutter build apk –debug 和** flutter build apk –release** 命令生成插件的 debug 和 release .arr 文件.

#!/bin/bash

root=`pwd`

. "${root}/script/util.sh"

echo "start flutter plugin aar copy......"

for line in $(cat .flutter-plugins)
do
    arr=(${line/=/ })
    name=${arr[0]}
    path=${arr[1]}
    plugin_name=`basename $path`
    plugin_dir=$(dirname $path)
    plugin=${path}android

    aar="${path}android/build/outputs/aar/${name}-${build}.aar"
    if [ ! -f $arr ]
    then
       cp -f $aar "${root}/publish/${build}"
    else
       echo "$aar is not exists"
    fi
done

echo "flutter plugin copy successfully!"
  • 拷贝 Flutter Module 生成的 .aar 文件给 Android Native 项目的 app/libs 目录 ${root}/script/copy.sh

HappyAndroid 为 Native 项目名称, Android Native 项目 和 Flutter Module 项目放到同一根目录下即可

#!/bin/bash

root=`pwd`

. "${root}/script/util.sh"

rm -rf "../HappyAndroid/app/libs/"
cp -r "${root}/publish/${build}/"  "../HappyAndroid/app/libs"

运行 shell 命令生成 .arr 文件 ${root}/script/build.sh

#!/bin/bash
root=`pwd`

. "${root}/script/project.sh"
. "${root}/script/plugin.sh"
. "${root}/script/copy.sh"
  • 生成 debug .aar 模拟器包: ./script/build.sh build=debug
  • 生成 debug .aar 真机包: ./script/build.sh build=debug
  • 生成 release .aar 真机包: ./script/build.sh build=release

image.png

最后,按照正常的 Android Native 工程运行方式运行项目,即可 Running!

常见问题

打包模式 运行模式 构建 依赖包 可运行
Debug 模拟器
- flutter build aot –release
- flutter build bundle –debug
android-arm-release/flutter.jar

android-x64/flutter.jar

条件:复制 flutter_assets 里面的isolate_snapshot_data 和 vm_snapshot_data 覆盖 aot 里面的 isolate_snapshot_data 和 vm_snapshot_data
真机
- flutter build aot –release
- flutter build bundle –debug
android-arm-release/flutter.jar
真机
- flutter build aot –release
- flutter build bundle –release
android-arm-release/flutter.jar
真机
- flutter build aot –release
- flutter build bundle –debug
android-arm/flutter.jar
Error:JIT runtime cannot run a precompiled snapshot
真机
- flutter build aot –debug
- flutter build bundle –debug
android-arm/flutter.jar

android-arm-release/flutter.jar

android-arm does not support AOT compilation
Release 模拟器
真机
- flutter build aot –release
- flutter build bundle –release
android-arm-release/flutter.jar

Author: sky
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