Flutter错误： uses-sdk:minSdkVersion 16 cannot be smaller than version 21 declared

前言

今天要做蓝牙通信的功能，我使用了flutter_reactive_ble这个库，但是在运行的时候发现一下错误

Launching lib/main.dart on AQM AL10 in debug mode...

/Users/macbook/Desktop/test/flutter/my_app/android/app/src/debug/AndroidManifest.xml Error:

``uses-sdk:minSdkVersion ``16 cannot be smaller than version ``21 declared in library [:reactive_ble_mobile] /Users/macbook/Desktop/test/flutter/my_app/build/reactive_ble_mobile/intermediates/merged_manifest/debug/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 ``21``,

``or use tools:overrideLibrary=``"com.signify.hue.flutterreactiveble" to force usage (may lead to runtime failures)

FAILURE: Build failed with an exception.

* What went wrong:

Execution failed ``for task ``':app:processDebugMainManifest'``.

> Manifest merger failed : uses-sdk:minSdkVersion ``16 cannot be smaller than version ``21 declared in library [:reactive_ble_mobile] /Users/macbook/Desktop/test/flutter/my_app/build/reactive_ble_mobile/intermediates/merged_manifest/debug/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 ``21``,

``or use tools:overrideLibrary=``"com.signify.hue.flutterreactiveble" to force usage (may lead to runtime failures)

* 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 4s

┌─ Flutter Fix ─────────────────────────────────────────────────────────────────────────────────┐

│ The plugin reactive_ble_mobile requires a higher Android SDK version. │

│ Fix ``this issue by adding the following to the file │

│ /Users/macbook/Desktop/test/flutter/my_app/android/app/build.gradle: │

│ android { │

│ defaultConfig { │

│ minSdkVersion ``21 │

│ } │

│ } │

│ │

│ Note that your app won't be available to users running Android SDKs below ``21``. │

│ Alternatively, ``try to find a version of ``this plugin that supports these lower versions of the │

│ Android SDK. │

│ For more information, see: │

│ https:``//docs.flutter.dev/deployment/android#reviewing-the-gradle-build-configuration │

└───────────────────────────────────────────────────────────────────────────────────────────────┘

Exception: Gradle task assembleDebug failed with exit code ``1

Exited

问题原因

自己项目的minSdkVersion比三方SDK的的minSdkVersion低，即版本不一致导致的。

解决办法

方法一

前往项目------>android------>app------>build.gradle文件搜索defaultConfig，将minSdkVersion修改成固定值即可

方法二

进入flutter环境安装目录/packages/flutter_tools/gradle（这里的flutter是环境变量中配置的flutter路径），搜索minSdkVersion，将值改为需求的版本即可（我这里改成21）