private void readComments(ReadSheet readSheet) {
        if (!xlsxReadContext.readWorkbookHolder().getExtraReadSet().contains(CellExtraTypeEnum.COMMENT)) {
            return;
        }
        CommentsTable commentsTable = commentsTableMap.get(readSheet.getSheetNo());
        if (commentsTable == null) {
            return;
        }
        Iterator<CellAddress> cellAddresses = commentsTable.getCellAddresses();
        while (cellAddresses.hasNext()) {
            CellAddress cellAddress = cellAddresses.next();
            XSSFComment cellComment = commentsTable.findCellComment(cellAddress);
            CellExtra cellExtra = new CellExtra(CellExtraTypeEnum.COMMENT, cellComment.getString().toString(),
                cellAddress.getRow(), cellAddress.getColumn());
            xlsxReadContext.readSheetHolder().setCellExtra(cellExtra);
            xlsxReadContext.analysisEventProcessor().extra(xlsxReadContext);
        }
    }
excel comments key: sheetNo value: CommentsTable
fastexcel-core/src/main/java/cn/idev/excel/analysis/v07/XlsxSaxAnalyser.java