weex build android 时出现 Annotation processors must be explicitly declared now 的问题

问题

运行 weex build android 命令时出现如下错误：

BUILD FAILED in 2s

    at checkExecSyncError (child_process.js:601:13)
    at Object.execSync (child_process.js:641:13)
    at C:\Users\feng\.xtoolkit\node_modules\weexpack\lib\build\android.js:156:20
    at new Promise ()
    at buildApp (C:\Users\feng\.xtoolkit\node_modules\weexpack\lib\build\android.js:152:10)
    at 
Error: Error: Command failed: call gradlew.bat  assembleRelease
isLibProject: false, isAppProject: true
weex_plugin: []

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:javaPreCompileRelease'.
> Annotation processors must be explicitly declared now.  The following dependencies on the compile classpath are found to contain annotation processor.  Please add them to the annotationProcessor configuration.
    - weexplugin-processor-1.3.jar (com.taobao.android:weexplugin-processor:1.3)
  Alternatively, set android.defaultConfig.javaCompileOptions.annotationProcessorOptions.includeCompileClasspath = true to continue with previous behavior.  Note that this option is deprecated and will be removed in the future.
  See https://developer.android.com/r/tools/annotation-processor-error-message.html for more details.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 2s

原因

工程依赖了 weexplugin-processor 的 jar 包，而 jar 包里面用到了注解。在新的 gradle 版本里，需要写新的 groovy 代码来对每个引用注解的地方单独配置。

解决办法

1.在 platforms\android\app\build.gradle 文件中，使用 javaCompileOptions

    defaultConfig {
        applicationId "com.weex.app"
        minSdkVersion project.appMinSdkVersion
        targetSdkVersion project.targetSdkVersion
        versionCode 1
        versionName "1.0.0"
        ndk {
            abiFilters "x86"
            abiFilters "armeabi"
        }
        //添加了javaCompileOptions 
        javaCompileOptions {
            annotationProcessorOptions {
                includeCompileClasspath true
            }
        }
    }

2.在 platforms\android\app\build.gradle 文件中，使用 annotationProcessor

dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    compile 'com.taobao.android:weex_sdk:0.16.0'
    compile 'com.google.code.findbugs:jsr305:2.0.1'
    compile 'com.squareup.okhttp:okhttp:2.3.0'
    compile 'com.squareup.okhttp:okhttp-ws:2.3.0'
    compile 'com.squareup.okio:okio:1.0.1'
    compile 'com.squareup.picasso:picasso:2.5.2'
    compile "com.alibaba:fastjson:${project.fastjsonLibVersion}"
    compile "com.android.support:support-v4:${project.supportLibVersion}"
    compile "com.android.support:appcompat-v7:${project.supportLibVersion}"
    compile "com.android.support:design:${project.supportLibVersion}"
    compile "com.android.support:support-annotations:${project.supportLibVersion}"
    compile 'com.taobao.android:weex_inspector:0.10.0.5'
    compile 'com.journeyapps:zxing-android-embedded:3.4.0'
    // PLUGIN GRADLE EXTENSIONS START
    compile 'com.taobao.android:weexplugin-loader:1.3'


    compile 'com.taobao.android:weexplugin-processor:1.3'
    //添加了annotationProcessor
    annotationProcessor 'com.taobao.android:weexplugin-processor:1.3'


    compile 'com.taobao.android:weexplugin-annotation:1.3'
    // PLUGIN GRADLE EXTENSIONS END
}

此时出现如下错误：

* What went wrong:
Could not resolve all files for configuration ':app:releaseAnnotationProcessorClasspath'.
> Could not find com.alibaba:fastjson:1.1.27-android.
  Searched in the following locations:
    - file:/F:/Android/SDK/extras/m2repository/com/alibaba/fastjson/1.1.27-android/fastjson-1.1.27-android.pom
    - file:/F:/Android/SDK/extras/m2repository/com/alibaba/fastjson/1.1.27-android/fastjson-1.1.27-android.jar
    - file:/F:/Android/SDK/extras/google/m2repository/com/alibaba/fastjson/1.1.27-android/fastjson-1.1.27-android.pom
    - file:/F:/Android/SDK/extras/google/m2repository/com/alibaba/fastjson/1.1.27-android/fastjson-1.1.27-android.jar
    - file:/F:/Android/SDK/extras/android/m2repository/com/alibaba/fastjson/1.1.27-android/fastjson-1.1.27-android.pom
    - file:/F:/Android/SDK/extras/android/m2repository/com/alibaba/fastjson/1.1.27-android/fastjson-1.1.27-android.jar
    - file:/C:/Users/feng/.m2/repository/com/alibaba/fastjson/1.1.27-android/fastjson-1.1.27-android.pom
    - file:/C:/Users/feng/.m2/repository/com/alibaba/fastjson/1.1.27-android/fastjson-1.1.27-android.jar
    - https://jcenter.bintray.com/com/alibaba/fastjson/1.1.27-android/fastjson-1.1.27-android.pom
    - https://jcenter.bintray.com/com/alibaba/fastjson/1.1.27-android/fastjson-1.1.27-android.jar
    - https://repo.maven.apache.org/maven2/com/alibaba/fastjson/1.1.27-android/fastjson-1.1.27-android.pom
    - https://repo.maven.apache.org/maven2/com/alibaba/fastjson/1.1.27-android/fastjson-1.1.27-android.jar
    - https://mvnrepository.com/com/alibaba/fastjson/1.1.27-android/fastjson-1.1.27-android.pom
    - https://mvnrepository.com/com/alibaba/fastjson/1.1.27-android/fastjson-1.1.27-android.jar
    - https://maven.google.com/com/alibaba/fastjson/1.1.27-android/fastjson-1.1.27-android.pom
    - https://maven.google.com/com/alibaba/fastjson/1.1.27-android/fastjson-1.1.27-android.jar
  Required by:
      project :app > com.taobao.android:weexplugin-processor:1.3

从问题中可以发现，此时无法加载 com.alibaba:fastjson:1.1.27-android 依赖。下载依赖（网址），然后将其放在 C:\Users\feng.m2\repository\com\alibaba\fastjson\1.1.27-android 目录下即可，如图

推荐使用方案2，因为错误提示中，说明 javaCompileOptions 方法之后可能被删除！

参考：
1.Mr.Smile填坑记——AndroidStudio3.0 Canary 8注解报错Annotation processors must be explicitly declared now.
2.Annotation processors must be explicitly declared now…
3.Could not find com.alibaba:fastjson:1.1.27-android #8