Foreword: Weird problems in development always appear, and the postures are different every time. Relog this FAQ.
Obviously all my configurations are fine, why does this problem occur?
Has this happened to most people?
Well, today we will figure it out for you step by step. If you can’t figure it out, then you are looking for an article.
It's easy if you want to use debug mode.
You can find it directly under the studio
Follow the steps above to find it, and it can be used in debug mode. Is it simple?
If you want to use the release mode, you must figure it out after reading it.
The prerequisite for using release is that you already have jks . If there is no jks, create a new one yourself, the steps are simple and easy on the Internet.
Give you a hyperlink Android signature and JKS file viewing method - short book 
https://www.jianshu.com/p/81c6c7d3390a
first step
Find the storage path of your jdk in the studio.
Do not know how to find jdk? All right. look at the picture below
Can you find it? Find the bin under this folder, which contains keytool.exe
The path I copied is H:\AndroidStudio4.0\jre\bin\keytool.exe
The second step is to find the jks of your project.
You can't find your jks? I tm, I can't help it either. Stop studying and let's go.
If so, let's move on.
The copied mine is D:\YLS_as_code\wuyie3.00\app\wuye3.jks
Ok, we can start to find our sha value again
start cmd
cd .android
The most critical step is coming, splicing together
H:\AndroidStudio4.0\jre\bin\keytool.exe -list -v -keystore D:\YLS_as_code\wuyie3.00\app\wuye3.jks
Enter your password, do you see ok?
Please give me a like, okay? It's hard work.