如何使用OkHTTP3/Retrofit2获取多部分多文件上传的进度？

Question

我正在使用Retrofit2在单个多部分请求中上传动态数量的文件.我的改装界面看起来像这样 -

public interface FileUploadService {  
    @Multipart
    @POST("upload")
    Call<ResponseBody> uploadMultipleFilesDynamic(
            @Part List<MultipartBody.Part> files);
}

现在我想跟踪这个多文件上传的进度.此解决方案解释了如何通过扩展在多部分请求中上载单个文件时取得进展RequestBody.虽然我似乎无法理解如何将此应用于我的多个文件请求.一个解决方案,我能想到的是要建立ProgressRequestBody通过扩展OkHTTP MultipartBody,而不是类RequestBody,但OkHTTP3实现了MultipartBody作为一个final类使其无法扩展.任何人都可以指出我正确的方向,因为它是一个巨大的阻止我无法向用户显示文件上传的进度.或者是否有任何我可以实现的工作来实现此功能？

Answer 1

我关注了这篇博文：https://medium.com/@PaulinaSadowska/display-progress-of-multipart-request-with-retrofit-and-rxjava-23a4a779e6ba，然后进行以下调整以显示总进度而不是单独文件的进展：

  private fun prepareFileParts(reportAttachments: MutableList<ReportAttachment>, emitter: FlowableEmitter<Double>): List<MultipartBody.Part> {
    val multiPartBodyList = mutableListOf<MultipartBody.Part>()

    var offset = 0L
    var totalLength = 0L

    // calculate the total length of all files
    for (attachment in reportAttachments) {
        val file = File(attachment.filePath)
        totalLength += file.length()
    }

    // create requestbody for each file and calculate the progression offset
    for (attachment in reportAttachments) {
        val file = File(attachment.filePath)
        val mimeType = attachment.mimeType

        val countingRequestBody = createCountingRequestBody(file, mimeType, emitter, offset, totalLength)
        offset += file.length()

        val multipartBody = MultipartBody.Part.createFormData("file", file.name, countingRequestBody)
        multiPartBodyList.add(multipartBody)
    }

    return multiPartBodyList
}

private fun createCountingRequestBody(file: File, mimeType: String, emitter: FlowableEmitter<Double>, offset: Long, totalLength: Long): RequestBody {
    val requestBody = RequestBody.create(MediaType.parse(mimeType), file)
    return CountingRequestBody(requestBody, object : CountingRequestBody.Listener {
        override fun onRequestProgress(bytesWritten: Long, contentLength: Long) {
            val progress: Double = 1.0 * (offset + bytesWritten) / totalLength
            emitter.onNext(progress)
        }
    })
}

如果需要，您还可以创建一个拦截器并将其添加到您的OkHttpClient. 默认情况下，这将跟踪所有传出 API 调用。它看起来像这样：

class UploadProgressInterceptor(private val progressListener: CountingRequestBody.Listener) : Interceptor {

override fun intercept(chain: Interceptor.Chain): Response {
    val originalRequest = chain.request()

    if (originalRequest.body() == null) {
        return chain.proceed(originalRequest)
    }

    val requestBody = originalRequest.body()
    requestBody?.let {
        val progressRequest = originalRequest.newBuilder()
                .method(originalRequest.method(), CountingRequestBody(it, progressListener))
                .build()
        return chain.proceed(progressRequest)
    }
    return chain.proceed(originalRequest)
}