androidstudio Gradle升级到3.0以上后遇到的问题及解决方案

升级后出现第一个问题：

1. Cannot set the value of read-only property 'outputFile' for ApkVariantOutputImpl_Decorated

解决方案：

官方给出的Api变更如下 （from: https://developer.android.google.cn/studio/build/gradle-plugin-3-0-0-migration#variant_api）：

Android 插件 3.0.0 引入了一些移除特定功能的 API 变更，可能会破坏您现有的构建。 后期版本的插件可能会引入新的公共 API 来取代破坏的功能。

变体输出

使用 Variant API 操作变体输出在新插件中已不再受支持。 不过，这种方式仍然适用于简单任务，例如在构建时更改 APK 名称，如下所示：

// 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"
    }
}
不过，涉及访问 outputFile 对象的更复杂任务不再奏效。 这是因为配置阶段期间不再创建变体特定的任务。 这就让插件无法提前了解其全部输出，不过，这会加快配置速度。

按照上边的文档改一下就好

2. 上边的改好了，跑一下就出现了下边的问题

Error:Cannot choose between the following configurations of project :android_sdk:
  - debugApiElements
  - debugRuntimeElements
  - releaseApiElements
  - releaseRuntimeElements
All of them match the consumer attributes:
  - Configuration 'debugApiElements':
      - Found com.android.build.api.attributes.BuildTypeAttr 'debug' but wasn't required.
      - Found com.android.build.gradle.internal.dependency.AndroidTypeAttr 'Aar' but wasn't required.
      - Found com.android.build.gradle.internal.dependency.VariantAttr 'debug' but wasn't required.
      - Found org.gradle.api.attributes.Usage 'java-api' but wasn't required.
  - Configuration 'debugRuntimeElements':
      - Found com.android.build.api.attributes.BuildTypeAttr 'debug' but wasn't required.
      - Found com.android.build.gradle.internal.dependency.AndroidTypeAttr 'Aar' but wasn't required.
      - Found com.android.build.gradle.internal.dependency.VariantAttr 'debug' but wasn't required.
      - Found org.gradle.api.attributes.Usage 'java-runtime' but wasn't required.
  - Configuration 'releaseApiElements':
      - Found com.android.build.api.attributes.BuildTypeAttr 'release' but wasn't required.
      - Found com.android.build.gradle.internal.dependency.AndroidTypeAttr 'Aar' but wasn't required.
      - Found com.android.build.gradle.internal.dependency.VariantAttr 'release' but wasn't required.
      - Found org.gradle.api.attributes.Usage 'java-api' but wasn't required.
  - Configuration 'releaseRuntimeElements':
      - Found com.android.build.api.attributes.BuildTypeAttr 'release' but wasn't required.
      - Found com.android.build.gradle.internal.dependency.AndroidTypeAttr 'Aar' but wasn't required.
      - Found com.android.build.gradle.internal.dependency.VariantAttr 'release' but wasn't required.
      - Found org.gradle.api.attributes.Usage 'java-runtime' but wasn't required.

解决：
android studio更新到3.0后，不支持apt了，适配仅需要修改以下两点：

• 1.移除module目录下的build.gradle中的 apply plugin: 'android-apt'
• 2.将apt改成annotationProcessor

第三个问题：

Configuration 'androidTestCompile' is obsolete and has been replaced with 'androidTestImplementation' and 'androidTestApi'.
It will be removed at the end of 2018. For more information see: http://d.android.com/r/tools/update-dependency-configurations.html

解决：
直接根据提示，将过时不用的api换掉就行了。 具体的变化请看：http://www.baidu.com/

• compile 改成implementation 或 api
• androidTestCompile改成androidTestImplementation
• testCompile 改成testImplementation

第四个问题

Unable to load class 'org.gradle.api.internal.component.Usage'.

解决方案：

• classpath 'com.novoda:bintray-release:0.3.4' 修改为
  classpath 'com.novoda:bintray-release:0.5.0'
  去掉bintray相关的引用

第五个问题

error: style attribute '@android:attr/windowEnterAnimation' not found.

解决方案：

• 当前已经不支持@开头使用android自带的属性，我们只要把@符号删掉就可以了。

目前升级到3.1.3只遇到上边几个问题，一切源于自己实践，如有不对，多多指教。