如何把apk编译时间和最后次git commit的sha值，写入到app中

apply plugin: ‘com.android.application‘

//创建当前时间字符创 比如 0411_1213 表示 4月11号，12点13分
def buildTime() {
    def date = new Date()
    def formattedDate = date.format(‘MMdd_HHmm‘)
    return formattedDate
}

//获取文件夹最后一次git commit的sha值
def gitSha = ‘git rev-parse --short HEAD‘.execute([], project.rootDir).text.trim()


android {
    compileSdkVersion 23
    buildToolsVersion "23.0.2"

    defaultConfig {
        applicationId "com.example.administrator.myapplication"
        minSdkVersion 14
        targetSdkVersion 23
        versionCode 1
        versionName "1.0"
        //在BuildConfig里面创建BUILD_TIME变量，代表apk编译时间
        buildConfigField "String", "BUILD_TIME", "\"${buildTime()}\""
        //在BuildConfig里面创建GIT_SHA变量，代表本项目最新git的commit的值
        buildConfigField "String", "GIT_SHA", "\"${gitSha}\""
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile(‘proguard-android.txt‘), ‘proguard-rules.pro‘
        }
    }
}

dependencies {
    compile fileTree(dir: ‘libs‘, include: [‘*.jar‘])
    testCompile ‘junit:junit:4.12‘
    compile ‘com.android.support:appcompat-v7:23.2.1‘
    compile ‘com.android.support:design:23.2.1‘
    compile ‘io.reactivex:rxandroid:1.1.0‘
    compile ‘io.reactivex:rxjava:1.1.2‘
}