按照上一篇博客的设置，已经可以愉快地玩flutter了。

但是，当我开始使用第三方package时（flutter_blue），安装依赖噩梦再次降临。

反正症状跟之前的一样。照理将gradle-wrapper.properties里的gradle版本改为4.6，但这次不管全局翻墙还是在Android studio里设置socks代理，都没有用。最后抱着试试看的心态把Android studio的proxy改为http代理，竟然不再报443了。。。

但安装依赖时候还是报错了。提示信息并未能看出啥来，于是切换到工程的android目录下，手动运行./gradlew build --stacktrace，看到这么一段信息：

* What went wrong:Execution failed for task ':app:processDebugManifest'.> Manifest merger failed : uses-sdk:minSdkVersion 16 cannot be smaller than version 19 declared in library [:flutter_blue] /Users/lynx/Android/flutter_app/build/flutter_blue/intermediates/merged_manifests/debug/processDebugManifest/merged/AndroidManifest.xml as the library might be using APIs not available in 16        Suggestion: use a compatible library with a minSdk of at most 16,                or increase this project's minSdk version to at least 19,                or use tools:overrideLibrary="com.pauldemarco.flutterblue" to force usage (may lead to runtime failures)

知道原因就好办了。打开app/build.gradle，把默认的minSdkVersion从16改为19，之后编译通过。