配置虚拟机的时候出现 Unable to locate adb，我搜了各种方法，有的说是Android默认的adb端口是5037，跟Windows上进程的端口冲突；有的说sdk没有选中等等等。然而，我挨个试了一下都没有用。直到——

我没有下载下来gradle：

 Gradle 原因： Gradle源在国外，国内构建项目的时候经常报错连接超时，修改国内镜像可以解决。

应该搜Android Studio: Gradle/Maven配置国内镜像源

1.打开Android Studio工程文件，找到build.gradle

2.使用文本编辑器打开，默认格式如下：

 3.全部注掉，加上

buildscript {repositories {maven {url 'https://maven.aliyun.com/repository/google'}maven {url 'https://maven.aliyun.com/repository/public'}maven {url 'https://maven.aliyun.com/repository/jcenter'}}dependencies {classpath 'com.android.tools.build:gradle:3.5.1'// NOTE: Do not place your application dependencies here; they belong// in the individual module build.gradle files}
}allprojects {repositories {maven {url 'https://maven.aliyun.com/repository/google'}maven {url 'https://maven.aliyun.com/repository/public'}maven {url 'https://maven.aliyun.com/repository/jcenter'}}
}task clean(type: Delete) {delete rootProject.buildDir
}

对所有项目生效
1.打开系统用户的Gradle配置目录：C:\Users\xxx\.gradle

2.新建txt文件

allprojects{repositories {def ALIYUN_REPOSITORY_URL = 'https://maven.aliyun.com/repository/public'def ALIYUN_JCENTER_URL = 'https://maven.aliyun.com/repository/jcenter'all { ArtifactRepository repo ->if (repo instanceof MavenArtifactRepository){def url = repo.url.toString()if (url.startsWith('https://repo1.maven.org/maven2')) {project.logger.lifecycle "Repository ${repo.url} replaced by $ALIYUN_REPOSITORY_URL."remove repo}if (url.startsWith('https://jcenter.bintray.com/')) {project.logger.lifecycle "Repository ${repo.url} replaced by $ALIYUN_JCENTER_URL."remove repo}}}maven {url ALIYUN_REPOSITORY_URLurl ALIYUN_JCENTER_URL}}
}

3.把文件名改成init.gradle（注意文件后缀名为gradle，如果没有，在任意文件夹里—查看—文件扩展名打开）