library/src/main/java/com/liulishuo/filedownloader/FileDownloader.java
public long getSoFar(final int downloadId) {
        BaseDownloadTask.IRunningTask task = FileDownloadList.getImpl().get(downloadId);
        if (task == null) {
            return FileDownloadServiceProxy.getImpl().getSofar(downloadId);
        }

        return task.getOrigin().getLargeFileSoFarBytes();
    }
public long getSoFar(final int downloadId) {
        BaseDownloadTask.IRunningTask task = FileDownloadList.getImpl().get(downloadId);
        if (task == null) {
            return FileDownloadServiceProxy.getImpl().getSofar(downloadId);
        }

        return task.getOrigin().getLargeFileSoFarBytes();
    }
Get downloaded bytes so far by the downloadId.