build.gradle

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

buildscript {
    repositories {
        jcenter()
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:2.3.1'
        classpath 'com.jakewharton:butterknife-gradle-plugin:8.8.1'  //添加这一行

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

allprojects {
    repositories {
        mavenCentral()
        jcenter()
    }
}

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

//Error:(36, 13) Failed to resolve: com.android.support:appcompat-v7:27.1.0
//<a href="install.m2.repo">Install Repository and sync project</a><br><a href="openFile:/Users/renzhenhua/Desktop/workspace/UI_study/app/build.gradle">Show in File</a><br><a href="open.dependency.in.project.structure">Show in Project Structure dialog</a>