fun downloadFile(url: String, dir: File, name: String?, fileExt: String?): File { val client = OkHttpClient() val request = Request.Builder().url(url).build() val response = client.newCall(request).execute() val contentType = response.header("content-type", null) var ext = MimeTypeMap.getSingleton().getExtensionFromMimeType(contentType) ext = if (ext == null) { fileExt } else { ".$ext" } // use provided name or generate a temp file var file: File? = null file = if (name != null) { val filename = String.format("%s%s", name, ext) File(dir.absolutePath, filename) } else { val timestamp = LocalDateTime.now().format(DateTimeFormatter.ofPattern("yyyyMMdd-kkmmss")) File.createTempFile(timestamp, ext, dir) } val body = response.body() val sink = Okio.buffer(Okio.sink(file)) /* sink.writeAll(body!!.source()) sink.close() body.close() */ body?.source().use { input -> sink.use { output -> output.writeAll(input) } } return file}The above method is blocking, so kotlin-couroutines is used (or you can use any threading library).
launch { try { val file = downloadFile("https://www.travelopy.com/static/img/cover.jpg", context.cacheDir, null, null) } catch (e: IOException) { }}If you perfer callback.
client.newCall(request).enqueue(object : Callback { override fun onFailure(call: Call, e: IOException) { } @Throws(IOException::class) override fun onResponse(call: Call, response: Response) { }})