آپلود فایل و نمایش پیشروی آن در کاتلین — از صفر تا صد

1@Multipart
2@POST("file")
3fun attachFile(
4    @Part("name") filename: RequestBody,
5    @Part("type") mimeType: RequestBody,
6    @Part("size") fileSize: RequestBody,
7    @Part filePart: MultipartBody.Part
8): Single<AttachmentUploadedRemoteDto>

1fun createUploadRequestBody(file: File, mimeType: String) = 
2    file.asRequestBody(mimeType.toMediaType())

1class CountingRequestBody(
2    private val requestBody: RequestBody,
3    private val onProgressUpdate: CountingRequestListener
4) : RequestBody() {
5    override fun contentType() = requestBody.contentType()
6
7    @Throws(IOException::class)
8    override fun contentLength() = requestBody.contentLength()
9
10    ...
11}

1typealias CountingRequestListener = (bytesWritten: Long, contentLength: Long) -> Unit
2
3class CountingSink(
4    sink: Sink,
5    private val requestBody: RequestBody,
6    private val onProgressUpdate: CountingRequestListener
7) : ForwardingSink(sink) {
8    private var bytesWritten = 0L
9
10    override fun write(source: Buffer, byteCount: Long) {
11        super.write(source, byteCount)
12
13        bytesWritten += byteCount
14        onProgressUpdate(bytesWritten, requestBody.contentLength())
15    }
16}

1class CountingRequestBody(...) : RequestBody() {
2    ...
3
4    @Throws(IOException::class)
5    override fun writeTo(sink: BufferedSink) {
6        val countingSink = CountingSink(sink, this, onProgressUpdate)
7        val bufferedSink = countingSink.buffer()
8
9        requestBody.writeTo(bufferedSink)
10
11        bufferedSink.flush()
12    }
13}

1sealed class CountingRequestResult<ResultT> {
2    data class Progress<ResultT>(
3        val progressFraction: Double
4    ) : CountingRequestResult<ResultT>()
5
6    data class Completed<ResultT>(
7        val result: ResultT
8    ) : CountingRequestResult<ResultT>()
9}

1private fun createUploadRequestBody(
2    file: File,
3    mimeType: String,
4    progressEmitter: PublishSubject<Double>
5): RequestBody {
6    val fileRequestBody = file.asRequestBody(mimeType.toMediaType())
7    return CountingRequestBody(fileRequestBody) { bytesWritten, contentLength ->
8        val progress = 1.0 * bytesWritten / contentLength
9        progressEmitter.onNext(progress)
10
11        if (progress >= 1.0) {
12            progressEmitter.onComplete()
13        }
14    }
15}

1private fun createUploadRequest(
2    filename: String,
3    file: File,
4    mimeType: String,
5    progressEmitter: PublishSubject<Double>
6): Single<AttachmentUploadedRemoteDto> {
7    val requestBody = createUploadRequestBody(file, mimeType, progressEmitter)
8    return remoteApi.attachFile(
9        filename = filename.toPlainTextBody(),
10        mimeType = mimeType.toPlainTextBody(),
11        fileSize = file.length().toString().toPlainTextBody(),
12        filePart = MultipartBody.Part.createFormData(
13            name = "files[]",
14            filename = filename,
15            body = requestBody
16        )
17    )
18}
19
20private fun String.toPlainTextBody() = toRequestBody("text/plain".toMediaType())

1fun uploadAttachment(
2    filename: String, file: File, mimeType: String
3): Observable<AttachmentUploadRemoteResult> {
4    val progressEmitter = PublishSubject.create<Double>()
5    val uploadRequest = createUploadRequest(
6        filename, file, mimeType, progressEmitter
7    )
8
9    val uploadResult = uploadRequest
10        .map<AttachmentUploadRemoteResult> { 
11            CountingRequestResult.Completed(it.result) 
12        }
13        .toObservable()
14
15    val progressResult = progressEmitter
16        .map<AttachmentUploadRemoteResult> { 
17            CountingRequestResult.Progress(it) 
18        }
19
20    return progressResult.mergeWith(uploadResult)
21}
22
23typealias AttachmentUploadRemoteResult = 
24    CountingRequestResult<AttachmentUploadedRemoteDto>

1uploader.uploadAttachment(request.filename, request.file, request.mimeType)
2    .subscribeOn(appRxSchedulers.io)
3    .observeOn(appRxSchedulers.main)
4    .subscribeBy(
5        onError = { error ->
6            // Display error alert
7        },
8        onComplete = {
9            // Display completed Snackbar
10        },
11        onNext = { progress ->
12            // Update progress bar
13        }
14    )
15    .addTo(disposeBag)