The specified Android SDK Build Tools version (23.0.2) is ignored,

The specified Android SDK Build Tools version (23.0.2) is ignored, as it is below the minimum supported version (28.0.3) for Android Gradle Plugin 3.2.1.
Android SDK Build Tools 28.0.3 will be used.
To suppress this warning, remove "buildToolsVersion '23.0.2'" from your build.gradle file, as each version of the Android Gradle Plugin now has a default version of the build tools.
Update Build Tools version and sync project
Open File
 

如果提示以下信息，则点击"Open File",将打开文件中buildToolsVersion的值修改为“28.0.3”或根据你的提示情况对应的版本。

为了避免报乱七八糟的错误，建议打开所有模块中的build.gradle文件，修改其中的compileSdkVersion、targetSdkVersion、minSdkVersion为适合你自已环境的对应版本，例如，我将我的compileSdkVersion、targetSdkVersion统一修改为27。

修改“com.android.support:appcompat-v7:”、“com.android.support:recyclerview-v7:”、“com.android.support:cardview-v7”、“com.android.support:design”对应的版本为“27.+”

工程下面的build.gradle参考如下配置：

buildscript {
    repositories {
        jcenter()
        mavenCentral()
        google()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.2.1'
        classpath 'com.github.dcendents:android-maven-gradle-plugin:1.5'
    }
}

allprojects {
    repositories {
        google()
        jcenter()
        maven { url "https://jitpack.io" }
    }
}

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