multi-part request (uploading an Image) with HttpURLConnection - age old method.

mokka.kt

class Dummy {
    //  make urlConnection -> multipart
    var attachmentName = "content"
    var attachmentFileName = "profile.jpeg"
    var crlf = "\r\n"
    var twoHyphens = "--"
    var boundary = "*****"
    var iStream: InputStream? = null

    //  multi part request
    fun makeAMultiPartRequest(imageBytes: ByteArray, token: String): String? {
        val url: URL? =
                when {
                    ConstantsUtil.USER_BD.readStringFromPref() == ConstantsUtil.BD_US ->
                        URL(END_POINT_US + UPLOAD_PHOTO_URL)
                    ConstantsUtil.USER_BD.readStringFromPref() == ConstantsUtil.BD_EU ->
                        URL(END_POINT_EU + UPLOAD_PHOTO_URL)
                    ConstantsUtil.USER_BD.readStringFromPref() == ConstantsUtil.BD_IND ->
                        URL(END_POINT_IND + UPLOAD_PHOTO_URL)
                    ConstantsUtil.USER_BD.readStringFromPref() == ConstantsUtil.BD_CHN ->
                        URL(END_POINT_CHN + UPLOAD_PHOTO_URL)
                    else ->
                        URL(END_POINT_US + UPLOAD_PHOTO_URL)
                }

        showVLog("IMAGE_UPLOAD url?.host: ${url?.host}")

        val httpUrlConnection = url?.openConnection() as HttpURLConnection
        httpUrlConnection.useCaches = false
        httpUrlConnection.doOutput = true
        httpUrlConnection.requestMethod = "POST"
        httpUrlConnection.setRequestProperty(ConstantsUtil.USER_AGENT, WorkerlyDelegate.appUserAgent)
        httpUrlConnection.setRequestProperty("Connection", "Keep-Alive")
        httpUrlConnection.setRequestProperty("Cache-Control", "no-cache")
        httpUrlConnection.setRequestProperty("Content-Type", "multipart/form-data;boundary=$boundary")
        httpUrlConnection.setRequestProperty(ConstantsUtil.AUTHORIZATION, token)
        httpUrlConnection.connect()

        val request = DataOutputStream(httpUrlConnection.outputStream)
        request.writeBytes(twoHyphens + boundary + crlf)
        request.writeBytes("Content-Disposition: form-data; name=\"" +
                attachmentName + "\";filename=\"" +
                attachmentFileName + "\"" + crlf)
        request.writeBytes(crlf)
        request.write(imageBytes)
        request.writeBytes(crlf)
        request.writeBytes(twoHyphens + boundary + twoHyphens + crlf)
        request.flush()
        request.close()

        //  get response
        val responseCode = httpUrlConnection.responseCode
        showVLog("IMAGE_UPLOAD responseCode :$responseCode")
        if (responseCode != 200) {
            iStream = httpUrlConnection.errorStream
            val response = readIStream(iStream)
            showVLog("IMAGE_UPLOAD ResponseCode != 200 response:$response")
            return null
        }
        iStream = httpUrlConnection.inputStream
        val response = readIStream(iStream)
        showVLog("IMAGE_UPLOAD ResponseCode == 200 response:$response")
        return response
    }

    //  read I stream
    private fun readIStream(iStream: InputStream?): String? {
        var reponseIs = ConstantsUtil.EMPTY
        iStream?.bufferedReader()?.useLines { lines ->
            lines.forEach {
                reponseIs += it
            }
        }
        return reponseIs
    }
}

SomeActivity.kt

//  API call from Android side
Observable.create<String> { emitter ->
            try {
                emitter.onNext(makeAMultiPartRequest(imageBytes, token)!!)
                emitter.onComplete()
            } catch (e: Exception) {
                e.printStackTrace()
                emitter.tryOnError(e)
            }
        }.compose(AppRxSchedulers.applySchedulers())
                .subscribe(
                        {
                            onNext
                            println("---IMAGE_UPLOAD it is : onNext: it:$it")
                        },
                        {
                            onError
                            println("---IMAGE_UPLOAD it is : onError: it.message:${it.message}")
                        },
                        {
                            onComplete
                            println("---IMAGE_UPLOAD it is : onComplete")
                        }
                )