library/src/main/java/com/liulishuo/filedownloader/util/FileDownloadUtils.java
public static boolean isAcceptRange(int responseCode, FileDownloadConnection connection) {
        if (responseCode == HttpURLConnection.HTTP_PARTIAL
                || responseCode == FileDownloadConnection.RESPONSE_CODE_FROM_OFFSET) return true;

        final String acceptRanges = connection.getResponseHeaderField("Accept-Ranges");
        return "bytes".equals(acceptRanges);
    }
public static boolean isAcceptRange(int responseCode, FileDownloadConnection connection) {
        if (responseCode == HttpURLConnection.HTTP_PARTIAL
                || responseCode == FileDownloadConnection.RESPONSE_CODE_FROM_OFFSET) return true;

        final String acceptRanges = connection.getResponseHeaderField("Accept-Ranges");
        return "bytes".equals(acceptRanges);
    }
accept range is effect by  response code and Accept-Ranges header field.