一、背景

一次工作任务是要解析excel数据，采用阿里的 easyexcel 工具进行解析，由于表格有合并单元格，但是 easyexcel 读取合并单元格只会读取一次，导致下面单元格数据为空，这样会影响有层级数据的识别，所以需要将合并单元格都填充上数据。由于我的excel列数是变化的，所以无法采用对象映射，获取出来的数据也是 List<Map<Integer, String>> 类型，废话不多说请看下面。

二、解决

2.0 先看一下处理结果

解析到一条数据:{"0":"*应用名称","1":"应用编码","2":"*一级菜单","3":"菜单编码","4":"*二级菜单","5":"菜单编码","6":"*功能菜单","7":"菜单编码","8":"功能角色1","9":"功能角色2","10":"功能角色3"}
解析到一条数据:{"0":"测试应用11","6":"全量","8":"√","10":"√"}
解析到一条数据:{"0":"测试应用22","2":"一级菜单1","4":"二级菜单1","6":"功能菜单1","8":"√","10":"√"}
解析到一条数据:{"6":"功能菜单2","9":"√","10":"√"}
解析到一条数据:{"6":"功能菜单3","10":"√"}
解析到一条数据:{"4":"二级菜单2","6":"功能菜单4","8":"√","10":"√"}
解析到一条数据:{"6":"功能菜单5","9":"√","10":"√"}
解析到一条数据:{"2":"一级菜单2","4":"二级菜单3","6":"功能菜单6","8":"√","10":"√"}
解析到一条数据:{"6":"功能菜单7","9":"√","10":"√"}
解析到一条数据:{"6":"功能菜单8","9":"√","10":"√"}
解析到一条数据:{"0":"测试应用33","2":"一级菜单3","6":"全量","8":"√","10":"√"}
解析到一条数据:{"2":"一级菜单4","6":"全量","10":"√"}
解析到一条数据:{"2":"一级菜单5","6":"全量","9":"√","10":"√"}
解析到一条数据:{"2":"一级菜单6","6":"全量","9":"√","10":"√"}

处理后数据:{"0":"*应用名称","1":"应用编码","2":"*一级菜单","3":"菜单编码","4":"*二级菜单","5":"菜单编码","6":"*功能菜单","7":"菜单编码","8":"功能角色1","9":"功能角色2","10":"功能角色3"}
处理后数据:{"0":"测试应用11","6":"全量","8":"√","10":"√"}
处理后数据:{"0":"测试应用22","2":"一级菜单1","4":"二级菜单1","6":"功能菜单1","8":"√","10":"√"}
处理后数据:{"0":"测试应用22","2":"一级菜单1","4":"二级菜单1","6":"功能菜单2","9":"√","10":"√"}
处理后数据:{"0":"测试应用22","2":"一级菜单1","4":"二级菜单1","6":"功能菜单3","10":"√"}
处理后数据:{"0":"测试应用22","2":"一级菜单1","4":"二级菜单2","6":"功能菜单4","8":"√","10":"√"}
处理后数据:{"0":"测试应用22","2":"一级菜单1","4":"二级菜单2","6":"功能菜单5","9":"√","10":"√"}
处理后数据:{"0":"测试应用22","2":"一级菜单2","4":"二级菜单3","6":"功能菜单6","8":"√","10":"√"}
处理后数据:{"0":"测试应用22","2":"一级菜单2","4":"二级菜单3","6":"功能菜单7","9":"√","10":"√"}
处理后数据:{"0":"测试应用22","2":"一级菜单2","4":"二级菜单3","6":"功能菜单8","9":"√","10":"√"}
处理后数据:{"0":"测试应用33","2":"一级菜单3","6":"全量","8":"√","10":"√"}
处理后数据:{"0":"测试应用33","2":"一级菜单4","6":"全量","10":"√"}
处理后数据:{"0":"测试应用33","2":"一级菜单5","6":"全量","9":"√","10":"√"}
处理后数据:{"0":"测试应用33","2":"一级菜单6","6":"全量","9":"√","10":"√"}

2.1 引入easyexcel依赖

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>easyexcel</artifactId>
    <version>3.0.5</version>
</dependency>

2.1 创建EasyExcelListener类

@Slf4j
public class EasyExcelListener extends AnalysisEventListener<Map<Integer, String>> {
    /**
     * 数据
     */
    List<Map<Integer, String>> dataList = new ArrayList<>();
    /**
     * 正文起始行
     */
    private Integer headRowNumber;
    /**
     * 合并单元格
     */
    private List<CellExtra> extraMergeInfoList = new ArrayList<>();

    public EasyExcelListener(Integer headRowNumber) {
        this.headRowNumber = headRowNumber;
    }

    @Override
    public void invoke(Map<Integer, String> data, AnalysisContext context) {
        log.info("解析到一条数据:{}", JSON.toJSONString(data));
        dataList.add(data);
    }

    /**
     * 读取额外信息：合并单元格
     */
    @Override
    public void extra(CellExtra extra, AnalysisContext context) {
        log.info("读取到了一条额外信息:{}", JSON.toJSONString(extra));
        switch (extra.getType()) {
            case MERGE: {
                if (extra.getRowIndex() >= headRowNumber) {
                    extraMergeInfoList.add(extra);
                }
                break;
            }
            default: break;
        }
    }

    @Override
    public void doAfterAllAnalysed(AnalysisContext analysisContext) {
        log.info("所有数据解析完成！");
    }

    /**
     * 返回解析出来的List
     */
    public List<Map<Integer, String>> getData() {
        return dataList;
    }

    /**
     * 返回解析出来的合并单元格List
     */
    public List<CellExtra> getExtraMergeInfoList() {
        return extraMergeInfoList;
    }
}

2.2 创建EasyExcelHelper类

@Slf4j
public class EasyExcelHelper<T> {
    /**
     * 返回解析后的List
     *
     * @param: fileName 文件名
     * @param: clazz Excel对应属性名
     * @param: sheetNo 要解析的sheet
     * @param: headRowNumber 正文起始行
     * @return java.util.List<T> 解析后的List
     */
    public List<Map<Integer, String>> getList(InputStream inputStream, Integer sheetNo, Integer headRowNumber) {
        EasyExcelListener listener = new EasyExcelListener(headRowNumber);
        try {
            EasyExcelFactory.read(inputStream, listener)
                    .excelType(ExcelTypeEnum.XLSX)
                    .extraRead(CellExtraTypeEnum.MERGE)
                    .sheet(sheetNo)
                    .headRowNumber(headRowNumber)
                    .doRead();
        } catch (Exception e) {
            log.error(e.getMessage());
        }
        List<CellExtra> extraMergeInfoList = listener.getExtraMergeInfoList();
        if (CollectionUtils.isEmpty(extraMergeInfoList)) {
            return listener.getData();
        }
        List<Map<Integer, String>> data = explainMergeData(listener.getData(), extraMergeInfoList, headRowNumber);
        return data;
    }

    /**
     * 处理合并单元格
     *
     * @param data               解析数据
     * @param extraMergeInfoList 合并单元格信息
     * @param headRowNumber      起始行
     * @return 填充好的解析数据
     */
    private List<Map<Integer, String>> explainMergeData(List<Map<Integer, String>> data, List<CellExtra> extraMergeInfoList, Integer headRowNumber) {
        //循环所有合并单元格信息
        extraMergeInfoList.forEach(cellExtra -> {
            int firstRowIndex = cellExtra.getFirstRowIndex() - headRowNumber;
            int firstColumnIndex = cellExtra.getFirstColumnIndex();
            int lastRowIndex = cellExtra.getLastRowIndex() - headRowNumber;
            int lastColumnIndex = cellExtra.getLastColumnIndex();
            // 获取初始值
            String initValue = getInitValueFromList(firstRowIndex, firstColumnIndex, data);
            // 设置值
            for (int i = firstRowIndex; i <= lastRowIndex; i++) {
                for (int j = firstColumnIndex; j <= lastColumnIndex; j++) {
                    setInitValueToList(initValue, i, j, data);
                }
            }
        });
        return data;
    }

    /**
     * 设置合并单元格的值
     *
     * @param filedValue  值
     * @param rowIndex    行
     * @param columnIndex 列
     * @param data        解析数据
     */
    public void setInitValueToList(String filedValue, Integer rowIndex, Integer columnIndex, List<Map<Integer, String>> data) {
        Map<Integer, String> object = data.get(rowIndex);
        object.put(columnIndex, String.valueOf(filedValue));
    }

    /**
     * 获取合并单元格的初始值
     * rowIndex对应list的索引
     * columnIndex对应实体内的字段
     *
     * @param firstRowIndex    起始行
     * @param firstColumnIndex 起始列
     * @param data             列数据
     * @return 初始值
     */
    private String getInitValueFromList(Integer firstRowIndex, Integer firstColumnIndex, List<Map<Integer, String>> data) {
        String filedValue = null;
        Map<Integer, String> object = data.get(firstRowIndex);
        for (Map.Entry<Integer, String> entry : object.entrySet()) {
            if (entry.getKey().equals(firstColumnIndex)) {
                filedValue = entry.getValue();
                break;
            }
        }
        return filedValue;
    }
}

2.3 测试使用

@PostMapping(value = "/upload", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
public Boolean uploadAuthTemplate(@RequestPart("file") MultipartFile file) {
	EasyExcelHelper<Map<Integer, String>> helper = new EasyExcelHelper<>();
	// 参数 文件流，sheet页号，头行号
    List<Map<Integer, String>> listData = helper.getList(file.getInputStream(), 0, 1);
    log.info(JSON.toJSONString(listData));
    return true;
}

三、结语

万般皆下品，唯有技术和远方。。。愿君有所收获。。。