build.gradle

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

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:2.3.3'
        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        jcenter()
        mavenCentral()
        maven { url 'https://jitpack.io' }
        maven { url "https://dl.bintray.com/thelasterstar/maven/" }
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}
ext{
    //编译的 SDK 版本，如API20
    compileSdkVersion = 25
    //构建工具的版本，其中包括了打包工具aapt、dx等,如API20对应的build-tool的版本就是20.0.0
    buildToolsVersion = "25.0.2"
    //兼容的最低 SDK 版本
    minSdkVersion = 14
    //向前兼容，保存新旧两种逻辑，并通过 if-else 方法来判断执行哪种逻辑
    targetSdkVersion = 25
}