A detailed explanation of implementation api embed

最近使用 Android Studio When working on project development,发现对 implementation、api、embed The usage is not very clear,Prepare an article here to summarize its usage scenarios or usage methods.

dependencies {  
// Moudle内可见：material对应的api,Only thereMoudleThe corresponding project is called
implementation 'com.google.android.material:material:1.3.0'  
// Dependency is conductive：依赖该MoudleEngineering otherModule,仍可使用gson对应的api  
api 'com.google.code.gson:gson:2.6.2'  
// 合并AAR：将boltspackaged into theMoudle,生成包含bolts的aar  
embed 'com.parse.bolts:bolts-tasks:1.4.0'
}

正文开始前,先对implementation、api、embedThe characteristics are summarized as follows：

一、implementation、api

implementation、api是Gradle与AGP(Android Gradle Plugin)Supported dependency configuration items：

• AndroidStudio官方文档描述如下：
  
• Gradle官方文档描述如下：
  

1.1 使用场景

implementation、api的使用场景或者使用方式A summary is given in the table at the beginning of the article：

implementation：

• 依赖Not conductive,引入的API仅Moudle可见;
• 参与Moudle的编译、Not participating in correspondenceAAR打包,But participate in the wholeApk打包;

api：

• 依赖具备传导性,依赖该Moudle的其他MoudleImported can also be calledAPI;
• 参与Moudle的编译、Not participating in correspondenceAAR打包,But participate in the wholeApk打包;

1.2 验证举例

A summary of the usage scenarios given above,This section provides the basis for the proof of the conclusion：The best way is to write a simple program to verify it.

• implementation Use scenario verification examples;
• api Use scenario verification examples;

implementationUse scenario validation

The verification steps and conclusions are as follows：

• a、新建一个AndroidStudio工程Android_Test;
• b、在Android_Test工程下,新建Moudle工程Lib_B;
• c、使App 依赖Lib_BMoudle工程;
  
• d、Lib_B以implementation方式引入gson依赖包：
  
• e、AppMoudle无法引用gson相关API：
  得出第一个结论：Dependence is not conductive,引入的API仅Moudle可见
  
• f、反编译Lib_B的AAR包,其中不包含gson相关代码;反编译app.apk,其中包含gson相关代码.
  得出第二个结论：参与Moudle的编译、Not participating in correspondenceAAR打包,But participate in the wholeApk打包
  

api

The verification steps and conclusions are as follows：

• a、Lib_B以api方式引入gson依赖包：
  
• b、AppMoudle可引用gson相关API：
  得出第一个结论：Dependency is conductive,依赖该Moudle的其他MoudleImported can also be calledAPI
  
• c、反编译Lib_B的AAR包,其中不包含gson相关代码;反编译app.apk,其中包含gson相关代码.
  得出第二个结论：参与Moudle的编译、Not participating in correspondenceAAR打包,But participate in the wholeApk打包
  

二、embed

embed 是GitHub开源工程 fat-aar-android Provided third-party dependency configuration,Its main function is将多个AARDependent packages are merged.

2.1 使用场景

Here's a summary of its use as follows：

• 合并AAR：将引入API对应的AARWorks merged into thisMoudle工程,Packed into a brand new oneAAR;
• 依赖Not conductive：引入的API仅Moudle可见;

2.2 注意点

对于embed的使用,No further verification examples are given here,感兴趣的朋友可自行验证.但对于embed的使用,A point to be emphasized here：

• a、fat-aar-android 将不再维护更新;
• b、Supported version range：AGP 3.0 - 7.1.0,Gradle 4.9 - 7.3;

三、A scene processing

implementation、api、embed单独使用,It has met most of our usage scenarios,But suppose this is the case：

• 有三个Moudle：app、Lib_B、Lib_C;
• app 依赖 Lib_B,Lib_B 依赖 Lib_C;

需求是 Lib_C Need to be merged into Lib_B 中,生成一个新的AAR Lib_B ;但 Lib_C 的相关APITo be available again app 调用.

这种情况该如何处理？

// can be used simultaneouslyapi与embed配置依赖
dependencies {
    api project(path: ':Lib_C')
    embed project(path: ':Lib_C')
}

参考

Android Gradle dependencies：
https://developer.android.google.cn/studio/build/dependencies?hl=zh-cn

fat-aar-android:embed
https://github.com/kezong/fat-aar-android

Gradle官方：
https://gradle.org/releases/

Gradle java_library_plugin：
https://docs.gradle.org/current/userguide/java_library_plugin.html#sec:java_library_separation

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