android studio 遇到failed to resolve: com.android.support:appcompat-v7:27

遇到这种问题 

在build.gradel下添加加粗的几行代码即可

buildTypes {
    repositories{
        maven{
            url "https://maven.google.com"
        }
    }
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    }
}