build.gradle

apply plugin: 'com.android.library'

version = rootProject.file('version').text.trim()

def generatedSrcDir = new File(buildDir, "generated/main/java/");

buildscript {
    repositories {
        google()
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.3.0'
    }
}

android {
    compileSdkVersion 26
    defaultConfig {
        minSdkVersion 16
        targetSdkVersion 26
        versionCode 1
        versionName version
        externalNativeBuild {
            cmake {
                cppFlags ""
            }
        }
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
        }
    }
    externalNativeBuild {
        cmake {
            path "CMakeLists.txt"
        }
    }

    task generateZstdVersion {
        doLast {
            ZstdVersionGenerator.generate(generatedSrcDir, version)
        }
    }

    preBuild.dependsOn generateZstdVersion

    sourceSets {
        main.java.srcDirs += generatedSrcDir
    }
}

repositories {
    google()
    jcenter()
    mavenCentral()
}

dependencies {
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
}

public class ZstdVersionGenerator {
	public static void generate(File outputDir, String version) throws Exception {
		String packageName = "com.github.luben.zstd.util";
		File packageDir = new File(outputDir, packageName.replace(".", "/"));
		packageDir.mkdirs();
		OutputStream outputStream = new FileOutputStream(new File(packageDir, "ZstdVersion.java"));
		try {
			def output = "package " + packageName + ";\n\npublic class ZstdVersion\n{\n\tpublic static final String VERSION = \"" + version + "\";\n}\n";
			outputStream.write(output.getBytes("UTF-8"));
		}
		finally {
			outputStream.close();
		}
	}
}