（转）https://blog.csdn.net/Aeve_imp/article/details/104910080
（官方文档）https://alibaba-easyexcel.github.io](https://alibaba-easyexcel.github.io/

public static void writeExcelWithHeadAndData(OutputStream outputStream, List<List<String>> head, List<List<String>> body, ExcelTypeEnum excelTypeEnum) {
/* ExcelWriter writer = new ExcelWriter(outputStream, excelTypeEnum,true);
Sheet sheet1 = new Sheet(1, 0);
//手动写表，赋予表头内容和数据
Table table = new Table(1);
table.setHead(head);
writer.write0(body, sheet1, table);
writer.finish();*/
Map<String, List<RowRangeDto>> stringListMap = addMerStrategy(body);
// 文件流会自动关闭
EasyExcel.write(outputStream)
.registerWriteHandler(new BizMergeStrategy(stringListMap))
.excelType(excelTypeEnum).
head(head).sheet(1,"运维周报").doWrite(body);
}
public static Map<String, List<RowRangeDto>> addMerStrategy(List<List<String>> excelDtoList) {
Map<String, List<RowRangeDto>> strategyMap = new HashMap<>();
List preExcelDto = null;
for (int i = 0; i < excelDtoList.size(); i++) {
List<String> currDto = excelDtoList.get(i);
if (preExcelDto != null) {
//从第二行开始判断是否需要合并
if (currDto.get(0).equals(preExcelDto.get(0))) {
//如果业务线一样，则可合并业务一列
fillStrategyMap(strategyMap, "0", i);
//如果业务线一样，并且模块一样，则可合并模块一列
if (currDto.get(1).equals(preExcelDto.get(1))) {
fillStrategyMap(strategyMap, "1", i);

                }
            }
        }
        preExcelDto = currDto;
    }
    return strategyMap;
}
private static void fillStrategyMap(Map<String, List<RowRangeDto>> strategyMap, String key, int index) {
    List<RowRangeDto> rowRangeDtoList = strategyMap.get(key) == null ? new ArrayList<>() : strategyMap.get(key);
    boolean flag = false;
    for (RowRangeDto dto : rowRangeDtoList) {
        //分段list中是否有end索引是上一行索引的，如果有，则索引+1
        if (dto.getEnd() == index) {
            dto.setEnd(index + 1);
            flag = true;
        }
    }
    //如果没有，则新增分段
    if (!flag) {
        rowRangeDtoList.add(new RowRangeDto(index, index + 1));
    }
    strategyMap.put(key, rowRangeDtoList);
}

/*

• 自定义合并单元格策略

• */
  public class BizMergeStrategy extends AbstractMergeStrategy{
  private Map<String, List<RowRangeDto>> strategyMap;
  private Sheet sheet;

  public BizMergeStrategy(Map<String, List<RowRangeDto>> strategyMap) {
  this.strategyMap = strategyMap;
  }

  @Override
  protected void merge(org.apache.poi.ss.usermodel.Sheet sheet, Cell cell, Head head, Integer integer) {
  this.sheet = sheet;
  if (cell.getRowIndex() == 1 && cell.getColumnIndex() == 0) {
  /**
  * 保证每个cell被合并一次，如果不加上面的判断，因为是一个cell一个cell操作的，
  * 例如合并A2:A3,当cell为A2时，合并A2,A3，但是当cell为A3时，又是合并A2,A3，
  * 但此时A2,A3已经是合并的单元格了
  */
  for (Map.Entry<String, List<RowRangeDto>> entry : strategyMap.entrySet()) {
  Integer columnIndex = Integer.valueOf(entry.getKey());
  entry.getValue().forEach(rowRange -> {
  // 添加一个合并请求
  sheet.addMergedRegionUnsafe(new CellRangeAddress(rowRange.getStart(),
  rowRange.getEnd(), columnIndex, columnIndex));
  });
  }
  }
  }

}
@Data
@NoArgsConstructor
@AllArgsConstructor
@ToString
public class RowRangeDto {
private int start;
private int end;
}