EasyExcel复杂导出 一对多

 将数据一条一条查出来 千万不要用一对多查询 最后用方法进行合并

public class ExcelFileCellMergeStrategy implements CellWriteHandler{

    /**
     * 合并列的范围索引
     */
    private int[] mergeColumnIndex;

    /**
     * 合并起始行索引
     */
    private int mergeRowIndex;

    /**
     * 合并校验列值
     */
    private int colIndex;


    public ExcelFileCellMergeStrategy(int[] mergeColumnIndex, int mergeRowIndex, int colIndex) {
        this.mergeColumnIndex = mergeColumnIndex;
        this.mergeRowIndex = mergeRowIndex;
        this.colIndex = colIndex;
    }


    @Override
    public void afterCellDispose(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, List<WriteCellData<?>> cellDataList, Cell cell, Head head, Integer relativeRowIndex, Boolean isHead) {

        //当前行
        int curRowIndex = cell.getRowIndex();
        //当前列
        int curColIndex = cell.getColumnIndex();
        //某行开始合并
        if (curRowIndex > mergeRowIndex) {
            //判断每行的第一列是否相同,相同时进行合并
            if (isSame(cell, curRowIndex)) {
                for (int columnIndex : mergeColumnIndex) {
                    //对应的列进行合并
                    if (curColIndex == columnIndex) {
                        mergeWithPrevRow(writeSheetHolder, cell, curRowIndex, curColIndex);
                        break;
                    }
                }
            }
        }
    }

    private Boolean isSame(Cell cell, int curRowIndex){
        //获取当前行的某列的数据
        Cell curCell = cell.getSheet().getRow(curRowIndex).getCell(colIndex);
        //当前行某列值
        Object curData = curCell.getCellTypeEnum() == CellType.STRING ? curCell.getStringCellValue() : curCell.getNumericCellValue();
        //获取当前行的上一行数据
        Cell preCell = cell.getSheet().getRow(curRowIndex - 1).getCell(colIndex);
        //上一行某列值
        Object preData = preCell.getCellTypeEnum() == CellType.STRING ? preCell.getStringCellValue() : preCell.getNumericCellValue();
        // 比较当前行的某列的单元格与上一行是否相同，相同合并当前单元格与上一行
        return curData.equals(preData);
    }

    private void mergeWithPrevRow(WriteSheetHolder writeSheetHolder, Cell cell, int curRowIndex, int curColIndex) {
        //获取当前行的当前列的数据和上一行的当前列数据，通过上一行数据是否相同进行合并
        Object curData = cell.getCellTypeEnum() == CellType.STRING ? cell.getStringCellValue() : cell.getNumericCellValue();
        Cell preCell = cell.getSheet().getRow(curRowIndex - 1 ).getCell(curColIndex);
        Object preData = preCell.getCellTypeEnum() == CellType.STRING ? preCell.getStringCellValue() : preCell.getNumericCellValue();
        //比较当前行的第一列的单元格与上一行是否相同，相同合并当前单元格与上一行
        if (curData.equals(preData)){
            Sheet sheet = writeSheetHolder.getSheet();
            List<CellRangeAddress> mergedRegions = sheet.getMergedRegions();
            boolean isMerged = false;
            for (int i = 0; i < mergedRegions.size() && !isMerged; i++) {
                CellRangeAddress cellAddresses = mergedRegions.get(i);
                //若上 一个单元格已经被合并，则先移出原有的合并单元，再重新添加合并单元
                if (cellAddresses.isInRange(curRowIndex - 1 , curColIndex)){
                    sheet.removeMergedRegion(i);
                    cellAddresses.setLastRow(curRowIndex);
                    sheet.addMergedRegion(cellAddresses);
                    isMerged = true;
                }
            }
            //若上一个单元格未被合并，则新增合并单元
            if (!isMerged){
                CellRangeAddress cellAddresses = new CellRangeAddress(curRowIndex - 1, curRowIndex, curColIndex, curColIndex);
                sheet.addMergedRegion(cellAddresses);
            }
        }
    }

}
这个是进行合并的类方法 到时候导入到类里面直接调用就行
可以直接粘贴复制 不需要修改