解决Error:All flavors must now belong to a named flavor dimension. Learn more at https://d.android.com

这个问题是Android studio升级到3.0之后，运行的时候会提示gradle要升级到3.5版本才能编译。于是我把我的gradle升级到了

 gradle-4.1-milestone-1 版本，是2017年7月份最新版本了。

于是我把主程序的build.gradle中的gradle版本改成了这个，具体指定哪个版本我也不知道，于是就写了个3.0+

 dependencies {
 classpath 'com.android.tools.build:gradle:3.0+' 
}

然后再次编译，又发现了毒。

提示：Error:All flavors must now belong to a named flavor dimension.Learn more at https://d.android.com/r/tools/flavorDimensions-missing-error-message.html

这个一个错误，意思是：所有的flavors都必须属于同一个风格。

=。=懵逼

去翻墙看了它提供的地址才知道：

 Plugin 3.0.0 includes a new dependency mechanism that automatically matches variants when consuming a library. This means an app's debug variant automatically consumes a library's debug variant, and so on. It also works when using flavors―an app's redDebug variant will consume a library's redDebug variant. To make this work, the plugin now requires that all flavors belong to a named flavor dimension ―even if you intend to use only a single dimension. Otherwise, you will get the following build error:
[cpp] view plain copy
Error:All flavors must now belong to a named flavor dimension. 
The flavor 'flavor_name' is not assigned to a flavor dimension. 
 To resolve this error, assign each flavor to a named dimension, as shown in the sample below. Because dependency matching is now taken care of by the plugin, you should name your flavor dimensions carefully. For example, if all your app and library modules use the foo dimension, you'll have less control over which flavors are matched by the plugin.

// Specifies a flavor dimension. 
flavorDimensions "color" 
productFlavors { 
  red { 
  // Assigns this product flavor to the 'color' flavor dimension. 
  // This step is optional if you are using only one dimension. 
  dimension "color" 
  ... 
 } 
 blue { 
  dimension "color" 
  ... 
 } 
} 

大致是说，Plugin 3.0.0之后有一种自动匹配消耗库的机制，便于debug variant 自动消耗一个库，然后就是必须要所有的flavor 都属于同一个维度。

为了避免flavor 不同产生误差的问题，应该在所有的库模块都使用同一个foo尺寸。

= 。=还是懵逼。说一堆依然不是很理解。

但是我们从中已经知道解决方案了：

在主app的build.gradle里面的

 defaultConfig {
 targetSdkVersion：***
minSdkVersion ：***
versionCode：***
 versionName ：***
//版本名后面添加一句话，意思就是flavor dimension 它的维度就是该版本号，这样维度就是都是统一的了
flavorDimensions "versionCode"
}

总结