poi excel 多表头 导出

// 标题
    HSSFRow rows = sheet.createRow(0);
    rows.setHeight((short) (30 * 20));
    HSSFCell cells = rows.createCell(0);
    cells.setCellStyle(styledate);
    cells.setCellValue("周安排");

    // 表头
    HSSFRow row = sheet.createRow(1);
    row.setHeight((short) (30 * 20));
    int startColumn = 0;
    for (int i = 0; i < columns.size(); i++) {
        if(i<3){
          sheet.setColumnWidth(i,5*512);
        }else{
          sheet.setColumnWidth(i,15*512);
        }

        HSSFCell cell = row.createCell(startColumn);
        Column column = columns.get(i);
        cell.setCellValue(column.getLabel());


        标题出来了，表头怎么没有出来？