Download the official demo when accessing google + to the SDK, and then a bunch of problems, so install the latest libraries of the installation.
But there are still the following mistakes.

Information:Gradle tasks [:app:generateDebugSources, :app:mockableAndroidJar, :app:prepareDebugUnitTestDependencies, :app:generateDebugAndroidTestSources]
Warning:WARNING: Dependency org.apache.httpcomponents:httpclient:4.0.1 is ignored for debug as it may be conflicting with the internal version provided by Android.
Warning:WARNING: Dependency org.apache.httpcomponents:httpclient:4.0.1 is ignored for release as it may be conflicting with the internal version provided by Android.
Error:Execution failed for task ':app:processDebugGoogleServices'.
> File google-services.json is missing. The Google Services Plugin cannot function without it. 
   Searched Location: 
  C:\Users\Administrator\Downloads\google-services-master\android\signin\app\src\debug\google-services.json
  C:\Users\Administrator\Downloads\google-services-master\android\signin\app\google-services.json
Information:BUILD FAILED
Information:Total time: 1.244 secs
Information:1 error
Information:2 warnings
Information:See complete output in console

That is to say, File google-services.json is missing.
This problem is not easy to solve. The ghost knows what kind of Ghost this google-services.json is.

In Stack Overflow, I found a quote from my buddy.
You should delete a line apply plugin: 'com.google.gms.google-services'
because "com.android.application" package already has same package.

Looking at the build.gradle file, there are two sentences:

apply plugin: 'com.android.application'
apply plugin: 'com.google.gms.google-services'

That is to say, com.android.application already contains the package com.google.gms.google-services. I can't find it because of repeated introduction. Why don't MD prompt for duplication and the prompt can't be found?