How to solve the problem that the project gradle is too low/after upgrading AndroidStudio, the project opens very slowly.
从低版本的gradle升级到高版本需要注意的地方：
1、修改项目根目录下的build.gradle文件里加载插件类的版本，对应为AS的版本，如我现在使用的是3.1.0
2、修改项目根目录下的gradle/wrapper目录里gradle-wrapper.properties的文件，指定gradle编译版本
Note:
Using As to upgrade the gradle version always prompts a timeout; we can directly visit https://services.gradle.org/distributions to download the required version, and then extract the downloaded package to the gradle cache directory (Windows directory system).
eg: in the md5 code folder under C:\Users\zhang.gradle\wrapper\dists\gradle-4.4-all