Android Studio 3.2.1解决错误信息"ABIs [armeabi] are not supported for platform. Supported ABIs are [arm64-v8a, armeabi-v7a, x86, x86_64]."

在用Android Studio 3.2.1导入以前的项目，进行编译的时候，报告如下错误信息：

FAILURE: Build failed with an exception.

* What went wrong:
A problem occurred configuring project ':app'.
> ABIs [armeabi] are not supported for platform. Supported ABIs are [arm64-v8a, armeabi-v7a, x86, x86_64].

* 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 0s

问题发生的原因在于以前的代码在build.gradle中指定了abiFilters 'armeabi',但是从NDK r17版本开始，已经不支持"armeabi、mips、mips64"这三种ABI了。

虽然可以简单的修改成abiFilters 'armeabi-v7a'，来解决问题，但是我们更希望能有一个办法，在老版本的支持abiFilters 'armeabi'的NDK上继续使用abiFilters 'armeabi'进行编译，用来兼容老设备。而在只支持abiFilters 'armeabi-v7a'的设备上，我们使用abiFilters 'armeabi-v7a'保证能编译通过。

我们通过执行NDK目录下的ndk-which输出的支持的ABI列表的方式获取当前的NDK是否支持abiFilters 'armeabi'，如果不支持，我们就设置为abiFilters 'armeabi-v7a'。

具体的操作如下图所示：

习惯于复制黏贴的懒人们，可以在下面复制代码：

def ndkWhich = new File(getNdkDirectory(),"ndk-which")

// from NDK r17 "armeabi、mips、mips64" not supported
try {
    def ndkWhichExec = ndkWhich.toString().execute() //ndk-which not exists cause exception
    def abiOutput = new ByteArrayOutputStream()
    ndkWhichExec.waitForProcessOutput(abiOutput, null)
    abiOutput = abiOutput.toString().toUpperCase()
    if (abiOutput.contains('USAGE:') && abiOutput.contains("ABI")) {
        if (abiOutput.contains("'armeabi'")) {
            abiFilters 'armeabi'
        } else {
            abiFilters 'armeabi-v7a'
        }
    } else {
        abiFilters 'armeabi'
    }
} catch (Exception  e) {
    abiFilters 'armeabi'
}

参考链接

• How to use exec() output in gradle
• Execute shell script in Gradle
• Projucer-generated Android Studio project build.gradle contains unsupported ndk abiFilter ‘armeabi’
• "No toolchains found in the NDK toolchains folder for ABI with prefix: mips64el-linux-android"
• Android NDK开发（五） 开发中遇到的问题汇总