An Android Kotlin class to track and update download progress by the DownloadManager.

DownloadProgressUpdater.kt

/**
 * Tracks download of a DownloadManager job and reports progress.
 */
internal class DownloadProgressUpdater(private val manager: DownloadManager, private val downloadId: Long, private var downloadProgressListener: DownloadProgressListener?) : Thread() {
    private val query: DownloadManager.Query = DownloadManager.Query()
    private var totalBytes: Int = 0

    interface DownloadProgressListener {
        fun updateProgress(progress: Long)
    }

    init {
        query.setFilterById(this.downloadId)
    }

    override fun run() {

        while (downloadId > 0) {
            Thread.sleep(250)

            manager.query(query).use {
                if (it.moveToFirst()) {

                    //get total bytes of the file
                    if (totalBytes <= 0) {
                        totalBytes = it.getInt(it.getColumnIndex(DownloadManager.COLUMN_TOTAL_SIZE_BYTES))
                    }

                    val downloadStatus = it.getInt(it.getColumnIndex(DownloadManager.COLUMN_STATUS))
                    val bytesDownloadedSoFar = it.getInt(it.getColumnIndex(DownloadManager.COLUMN_BYTES_DOWNLOADED_SO_FAR))

                    if (downloadStatus == DownloadManager.STATUS_SUCCESSFUL || downloadStatus == DownloadManager.STATUS_FAILED) {
                        this.interrupt()
                    } else {
                        //update progress
                        val percentProgress = ((bytesDownloadedSoFar * 100L) / totalBytes)
                        Timber.d("Download progress: $percentProgress")
                        downloadProgressListener?.updateProgress(percentProgress)
                    }

                }
            }
        }

        if (downloadProgressListener != null) {
            downloadProgressListener = null
        }
    }

}

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