android studio: 子模块 Could not find aar 的问题

简单说下遇到的问题：

主模块app 依赖子模块 lib_ffmpeg, 子模块lib_ffmpeg 依赖一个aar: baidu-sdk.aar. 但是在编译时 gradle 始终提示：cound not find baidu-sdk.aar. 可我在lib_ffmepg的build.gradle文件里已添加：

implementation(name: 'baidu-sdk', ext: 'aar')

解决办法

1. 找到项目级别的build.gradle, 添加红字部分：

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
    repositories {
        maven { url 'https://maven.aliyun.com/repository/public' }
        maven { url 'https://maven.aliyun.com/repository/google' }
        maven { url 'https://maven.aliyun.com/repository/jcenter' }
        maven { url 'https://maven.aliyun.com/repository/central' }
        maven { url 'https://maven.aliyun.com/repository/gradle-plugin' }
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:7.0.1'

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        maven { url 'https://maven.aliyun.com/repository/public' }
        maven { url 'https://maven.aliyun.com/repository/google' }
        maven { url 'https://maven.aliyun.com/repository/jcenter' }
        maven { url 'https://maven.aliyun.com/repository/central' }
        maven { url 'https://maven.aliyun.com/repository/gradle-plugin' }

        flatDir {
            dirs project(':lib_ffmpeg').file('libs') // 我的aar文件已放置到 lib_ffmpeg 模块的libs目录下
        }
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

2. 找到 lib_ffmepg的build.gradle文件，删除(如果之前已添加)：

implementation(name: 'baidu-sdk', ext: 'aar')

因为上述gradle文件里已指定：

implementation fileTree(dir: 'libs', include: ['*.aar', '*.jar'], exclude: [])

完成上述两步后，重新sync下项目就好了。第二步如果不做的话可能会报 Duplicate class 的错误。

参考链接：
1. 疑难杂症（一）集成优酷sdk[aar] library Module 依赖,找不到aar[Could not find :YoukuPlayerOpenSDK-release:.]
2. Android Studio多Module使用 aar 依赖包 丢包解决