打开项目级别的 build.gradle 文件.

添加以下代码段:

allprojects {
    repositories {
        // ...
        maven { url 'https://jitpack.io' }
    }
}

然后在buildscript中，添加一个对象 ext ，如下所示.现在，将属性定义为 poiVersion 并为其分配值 3.17 .

Then, inside buildscript, add an object ext as below. Now, define a attribute as poiVersion and assign the value 3.17 to it.

这类似于定义名称为"poiVersion"的变量并将值分配为"3.17"

This is similar to defining a variable with name as "poiVersion" and assigning value as "3.17"

buildscript {
    repositories {
        ...
    }

    ext {
        poiVersion = '3.17'
    }

    dependencies {
        ...
    }
}

要访问该变量，您可以使用$ {variable_name}，如您的情况，您可以使用 $ poiVersion

And to access that variable you can use ${variable_name} as in your case, you used $poiVersion