buildscript和allprojects的作用和区别是什么？

在Android Studio的Project的build.gradle中，

// 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:2.3.0'
        classpath 'com.novoda:bintray-release:0.4.0'

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

allprojects {
    repositories {
        jcenter()
        maven {url 'https://dl.bintray.com/calvinning/maven'}
    }
}

那么buildscript中的repositories和allprojects的repositories的作用和区别是什么呢？
答：
1、 buildscript里是gradle脚本执行所需依赖，分别是对应的maven库和插件
2、 allprojects里是项目本身需要的依赖，比如我现在要依赖我自己maven库的toastutils库，那么我应该将maven {url 'https://dl.bintray.com/calvinning/maven'}写在这里，而不是buildscript中，不然找不到。

• The "buildscript" configuration section is for gradle itself (i.e. changes to how gradle is able to perform the build). So this section will usually include the Android Gradle plugin.
• The "allprojects" section is for the modules being built by Gradle.
• Oftentimes the repository section is the same for both, since both will get their dependencies from jcenter usually (or maybe maven central). But the "dependencies" section will be different.
• Usually the "dependencies" section for "allprojects" is empty since the dependencies for each module are unique and will be in the "build.gradle" file within each of the modules. However, if all of the modules shared the same dependencies then they could be listed here.