将旧项目迁移到AndroidStudio3.0

1.aapt2编译不过去

Error:Execution failed for task ':app:mergeDebugResources'.
> Error: java.util.concurrent.ExecutionException: com.android.tools.aapt2.Aapt2Exception: AAPT2 error: check logs for details

原来的项目用到了kotlin以及kapt，升级到了androidstudio 3.0报了上面的错误,需要在项目的gradle.properties中添加：

android.enableAapt2=false

关闭aapt2。

2.All flavors must now belong to a named flavor dimension

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

官方文档：

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:

Android Plugin3.0的依赖机制：在使用library时会自动匹配variant（debug, release)，就是说app的debug会自动匹配library的debug，相信大多数人也像我一样，当library多了，不会手动选择每个Library的variant。现在好了，它会自动匹配了。同样如果使用flavor的时候，比如app的redDebug同样会自动匹配library的readDebug。虽然有这样的优势，但是在使用flavor时，必须定义flavor dimension,否则会提示错误：

Error:All flavors must now belong to a named flavor dimension.
The flavor 'flavor_name' is not assigned to a flavor dimension.

现在使用flavor，必须像下面一样配置：

// 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"
      ...
    }
}

• 注意：如果library有两个dimensions:color,shape,但是app只有color,那么会如下的编译错误：

Error:Could not resolve all dependencies for configuration ':bar:redDebugCompileClasspath'.
Cannot choose between the following configurations on project :foo:
  - redCircleDebugApiElements
  - redSquareDebugApiElements
  ...

• 在APP使用flavorSelection选定使用某个flavor dimension，注意如下配置：

android {
  ...
  // The flavorSelection property uses the following format:
  // flavorSelection 'dimension_name', 'flavor_name'

  // Chooses the 'square' flavor from libraries that specify a 'shape'
  // dimension.
  flavorSelection 'shape', 'square'
}

参考文章

3.Cannot set the value of read-only property 'outputFile’….

Android plugin 3.0 migration guide 建议:

• 使用 all()代替 each()
• 使用 outputFileName代替 output.outputFile，如果你只想更改文件名称

// If you use each() to iterate through the variant objects,
// you need to start using all(). That's because each() iterates
// through only the objects that already exist during configuration time—
// but those object don't exist at configuration time with the new model.
// However, all() adapts to the new model by picking up object as they are
// added during execution.
android.applicationVariants.all { variant ->
    variant.outputs.all {
        outputFileName = "${variant.name}-${variant.versionName}.apk"
    }
}

参考如下：

applicationVariants.all { variant ->
    variant.outputs.all { output ->
        def newApkName = applicationId + "-" + variant.versionName + "(" + variant.versionCode + ")" + ".apk";
        outputFileName = new File("${project.projectDir}/../outputs/apks/" + variant.name, newApkName);
    }
}

参考文章

3.You should manually set the same version via DependencyResolution

参考文章

另一种姿势：

configurations.all {  
    resolutionStrategy.force 'rubygems:rb-inotify:0.9.5'  
}