Ktor support request with gzip on the Android platform.

KtorExtensions.kt

ktorHttpClient.post("xxxx") {
  tryCompress(this, json)
}

private fun tryCompress(httpRequestBuilder: HttpRequestBuilder, json: JSONObject) {
  val stringBody = tryCreateRequestBody(json = json)
  if (stringBody.length > 4096) {
    httpRequestBuilder.body = stringBody.gzipCompress()
    httpRequestBuilder.headers[HttpHeaders.ContentEncoding] = "gzip"
  } else {
    httpRequestBuilder.body = stringBody
  }
  httpRequestBuilder.body = stringBody
}

fun String.gzipCompress(): ByteArray {
  val byteArrayOutputStream = ByteArrayOutputStream()
  return byteArrayOutputStream.use { stream ->
      GZIPOutputStream(stream).bufferedWriter(Charsets.UTF_8)
          .use { writer -> writer.write(this) }
      stream.toByteArray()
  }
}

fun ByteArray.gzipDecompress(): String {
  val byteArrayInputStream = ByteArrayInputStream(this)
  byteArrayInputStream.use { stream ->
      GZIPInputStream(stream).bufferedReader(Charsets.UTF_8)
          .use { reader -> return reader.readText() }
  }
}