JAVA EasyExcel自定义合并单元格

1，需求：

因为项目需要所以要按要求合并excel表数据

2，实现方法，java的easyExcel

因为实现合并需继承AbstractMergeStrategy类重写merge方法，在merger中按自己的需要去合并数据

package com.ironge.yangtse.server.handler;

import com.alibaba.excel.metadata.Head;
import com.alibaba.excel.write.merge.AbstractMergeStrategy;
import com.ironge.yangtse.server.modules.dto.resp.ExportExamPlanResp;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.util.CellRangeAddress;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

public class ExamPlanExportMergeHandler extends AbstractMergeStrategy {
    //分组 用于记录多少组合并
    private List exportFieldGroupCountList = new ArrayList<>();

    public ExamPlanExportMergeHandler(List list, Map> groupByResult){
        Integer firstCol = 1;
//如果只合并一行/一列会报错，所以合并数据只有一的时候跳过，不合并
        if(list != null && list.size() > 0) {
            for(Integer planIds : groupByResult.keySet()) {
                //计算每次合并几列
                exportFieldGroupCountList.add(groupByResult.get(planIds).size());
            }
        }
        else{
            exportFieldGroupCountList = new ArrayList();
        }
    }

    @Override
    protected void merge(Sheet sheet, Cell cell, Head head, Integer integer) {
        Integer lastRow = 1;
        for (Integer indexCount : exportFieldGroupCountList) {
            //计算每次合并几列
            // int firstRow, int lastRow, int firstCol, int lastCol
            //CellRangeAddress cellRangeAddress = new CellRangeAddress(0,0,1,lastCol);
            if(indexCount > 1) {
// int firstRow, int lastRow, int firstCol, int lastCol
                CellRangeAddress cellRangeAddress = new CellRangeAddress(lastRow, lastRow + indexCount - 1, 0, 0);
            CellRangeAddress cellRangeAddress1 = new CellRangeAddress(lastRow, lastRow+indexCount-1, 1, 1);
            CellRangeAddress cellRangeAddress2 = new CellRangeAddress(lastRow, lastRow+indexCount-1, 10, 10);
            CellRangeAddress cellRangeAddress3 = new CellRangeAddress(lastRow, lastRow+indexCount-1, 11, 11);
            CellRangeAddress cellRangeAddress4 = new CellRangeAddress(lastRow, lastRow+indexCount-1, 12, 12);
            sheet.addMergedRegionUnsafe(cellRangeAddress);
            sheet.addMergedRegionUnsafe(cellRangeAddress1);
            sheet.addMergedRegionUnsafe(cellRangeAddress2);
            sheet.addMergedRegionUnsafe(cellRangeAddress3);
            sheet.addMergedRegionUnsafe(cellRangeAddress4);
                lastRow += indexCount;
            }
        }
    }
}

    @PostMapping("/exportGetList")
    @ApiOperation("导出计划")
    public void exportGetList(@RequestBody GetExamPlanReq req,HttpServletResponse response) {
        req.setCurrent(0);
        req.setSize(1000000);
        PageDto dto = examPlanService.getList(req);
        List list = dto.getList().stream().map(e->{return examPlanConvert.toExport(e);}).collect(Collectors.toList());
        Map> groupByResult = list.stream().collect(Collectors.groupingBy(ExportExamPlanResp::getId));
        String fileName = "考试计划";
        try (OutputStream out = response.getOutputStream()) {
            response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
            response.setCharacterEncoding("utf-8");
            // 这里URLEncoder.encode可以防止中文乱码 当然和easyexcel没有关系
            fileName = URLEncoder.encode(fileName, "UTF-8").replaceAll("\\+", "%20");
            response.setHeader("Content-disposition", "attachment;filename*=utf-8''" + fileName +".xlsx");
//这里是重点，这里要实例化上面的处理类，并传递参数，list为要写入的集合，groupBuresult为分组后的写入数据，用于区分多少行合并
            EasyExcel.write(out, ExportExamPlanResp.class)
                    .registerWriteHandler(new ExamPlanExportMergeHandler(list,groupByResult))
                    .sheet("sheet")
                    .doWrite(list);
        } catch (IOException e) {
            log.error("文件导出异常", e);
            throw new BusinessException(YangErrorCodeEnum.FILE_DOWNLOAD_FAILED);
        }
    }