常用的EasyExcel表格处理-2（动态合并、自适应宽高）

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1、动态合并单元格

此处主要根据自定义处理类ExcelFillCellMergeStrategy进行处理，具体内容可看代码注释。

1.1 前端调用controller

  @PostMapping("/download/template")
    public void toDoExport(HttpServletResponse response) {
        // 设置模拟表头（此处为多表头，也可以传入单表头）
        List<List<String>> headList = new ArrayList<>();
        List<String> heads1 = new ArrayList<>();
        heads1.add("总表头");
        heads1.add("表头1");
        headList.add(heads1);

        List<String> heads2 = new ArrayList<>();
        heads2.add("总表头");
        heads2.add("表头2");
        headList.add(heads2);

        List<String> heads3 = new ArrayList<>();
        heads3.add("总表头");
        heads3.add("表头3");
        headList.add(heads3);

        List<String> heads4 = new ArrayList<>();
        heads4.add("总表头");
        heads4.add("表头4");
        headList.add(heads4);
        // 设置模拟内容
        List<List<String>> data = new ArrayList<>();
        List<String> data1 = new ArrayList<>(); // 第1行的内容
        data1.add("内容1");
        data1.add("内容1-2");
        data1.add("内容3");
        data1.add("内容4");
        List<String> data2 = new ArrayList<>();// 第2行的内容
        data2.add("内容1");
        data2.add("内容2-2");
        data2.add("内容3");
        data2.add("内容4");
        data.add(data1);
        data.add(data2);
        try {
            response.setContentType("application/vnd.ms-excel");
            response.setCharacterEncoding("utf-8");
            // 防止中文乱码
            String fileName = URLEncoder.encode("导入模板名称", "UTF-8");
            response.setHeader("Content-disposition", "attachment;filename=" + fileName + ".xlsx");
            ServletOutputStream outputStream = response.getOutputStream();
            ExcelWriter writer = EasyExcel.write(outputStream).build();
            WriteSheet sheet = EasyExcel.writerSheet(0).needHead(Boolean.FALSE).sheetName("sheet页名称").build();
            WriteTable table1 = EasyExcel.writerTable(1).head(headList)
                    // 设置只合并第1、2、3列，其余不合并
                    .registerWriteHandler(new ExcelFillCellMergeStrategy(1,new int[]{0,1,2}))
                    .needHead(Boolean.TRUE).build();
            writer.write(data, sheet, table1); // data
            writer.finish();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

1.2 批注渲染处理类（ExcelFillCellMergeStrategy）

import com.alibaba.excel.metadata.CellData;
import com.alibaba.excel.metadata.Head;
import com.alibaba.excel.write.handler.CellWriteHandler;
import com.alibaba.excel.write.metadata.holder.WriteSheetHolder;
import com.alibaba.excel.write.metadata.holder.WriteTableHolder;
import lombok.Data;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.CellType;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.util.CellRangeAddress;
 
import java.util.List;
 
 
@Data
public class ExcelFillCellMergeStrategy implements CellWriteHandler {
    /**
     * 合并字段的下标，如第一到五列new int[]{0,1,2,3,4}
     */
    private int[] mergeColumnIndex;
    /**
     * 从第几行开始合并，如果表头占两行，这个数字就是2
     */
    private int mergeRowIndex;
 
    public ExcelFillCellMergeStrategy() {
    }
 
    public ExcelFillCellMergeStrategy(int mergeRowIndex, int[] mergeColumnIndex) {
        this.mergeRowIndex = mergeRowIndex;
        this.mergeColumnIndex = mergeColumnIndex;
    }
 
    @Override
    public void beforeCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Row row,
                                 Head head, Integer integer, Integer integer1, Boolean aBoolean) {
 
    }
 
    @Override
    public void afterCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Cell cell,
                                Head head, Integer integer, Boolean aBoolean) {
 
    }
 
    @Override
    public void afterCellDataConverted(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder,
                                       CellData cellData, Cell cell, Head head, Integer integer, Boolean aBoolean) {
 
    }
 
    @Override
    public void afterCellDispose(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder,
                                 List<CellData> list, Cell cell, Head head, Integer integer, Boolean aBoolean) {
        //当前行
        int curRowIndex = cell.getRowIndex();
        //当前列
        int curColIndex = cell.getColumnIndex();
 
        if (curRowIndex > mergeRowIndex) {
            for (int i = 0; i < mergeColumnIndex.length; i++) {
                if (curColIndex == mergeColumnIndex[i]) {
                    mergeWithPrevRow(writeSheetHolder, cell, curRowIndex, curColIndex);
                    break;
                }
            }
        }
    }
 
    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> mergeRegions = sheet.getMergedRegions();
            boolean isMerged = false;
            for (int i = 0; i < mergeRegions.size() && !isMerged; i++) {
                CellRangeAddress cellRangeAddr = mergeRegions.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 (cellRangeAddr.isInRange(curRowIndex - 1, curColIndex)) {
                    sheet.removeMergedRegion(i);
                    cellRangeAddr.setLastRow(curRowIndex);
                    sheet.addMergedRegion(cellRangeAddr);
                    isMerged = true;
                }
            }
            // 若上一个单元格未被合并，则新增合并单元
            if (!isMerged) {
                CellRangeAddress cellRangeAddress = new CellRangeAddress(curRowIndex - 1, curRowIndex, curColIndex,
                        curColIndex);
                sheet.addMergedRegion(cellRangeAddress);
            }
        }
    }
}

1.3 效果
通过传递参数控制了只合并前3列，第4列不合并，效果如图

2、自适应列宽、行高

2.1 自适应列宽
此处主要根据自定义处理类CustomCellWriteWeightConfig进行处理。

public class CustomCellWriteWeightConfig extends AbstractColumnWidthStyleStrategy {
    private Map<Integer, Map<Integer, Integer>> CACHE = new HashMap<>();

    @Override
    protected void setColumnWidth(WriteSheetHolder writeSheetHolder, List<CellData> cellDataList, Cell cell, Head head, Integer integer, Boolean isHead) {
        boolean needSetWidth = isHead || !CollectionUtils.isEmpty(cellDataList);
        if (needSetWidth) {
            Map<Integer, Integer> maxColumnWidthMap = CACHE.get(writeSheetHolder.getSheetNo());
            if (maxColumnWidthMap == null) {
                maxColumnWidthMap = new HashMap<>();
                CACHE.put(writeSheetHolder.getSheetNo(), maxColumnWidthMap);
            }

            Integer columnWidth = this.dataLength(cellDataList, cell, isHead);
            if (columnWidth >= 0) {
                if (columnWidth > 254) {
                    columnWidth = 254;
                }

                Integer maxColumnWidth = maxColumnWidthMap.get(cell.getColumnIndex());
                if (maxColumnWidth == null || columnWidth > maxColumnWidth) {
                    maxColumnWidthMap.put(cell.getColumnIndex(), columnWidth);
                    Sheet sheet = writeSheetHolder.getSheet();
                    sheet.setColumnWidth(cell.getColumnIndex(), columnWidth * 256);
                }

            }
        }
    }

    /**
     * 计算长度
     * @param cellDataList
     * @param cell
     * @param isHead
     * @return
     */
    private Integer dataLength(List<CellData> cellDataList, Cell cell, Boolean isHead) {
        if (isHead) {
            return cell.getStringCellValue().getBytes().length;
        } else {
            CellData cellData = cellDataList.get(0);
            CellDataTypeEnum type = cellData.getType();
            if (type == null) {
                return -1;
            } else {
                switch (type) {
                    case STRING:
                        // 换行符（数据需要提前解析好）
                        int index = cellData.getStringValue().indexOf("\n");
                        return index != -1 ?
                                cellData.getStringValue().substring(0, index).getBytes().length + 1 : cellData.getStringValue().getBytes().length + 1;
                    case BOOLEAN:
                        return cellData.getBooleanValue().toString().getBytes().length;
                    case NUMBER:
                        return cellData.getNumberValue().toString().getBytes().length;
                    default:
                        return -1;
                }
            }
        }
    }
}

2.2 自适应行高
此处主要根据自定义处理类CustomCellWriteHeightConfig进行处理。

public class CustomCellWriteHeightConfig extends AbstractRowHeightStyleStrategy {
    /**
     * 默认高度
     */
    private static final Integer DEFAULT_HEIGHT = 300;

    @Override
    protected void setHeadColumnHeight(Row row, int relativeRowIndex) {
    }

    @Override
    protected void setContentColumnHeight(Row row, int relativeRowIndex) {
        Iterator<Cell> cellIterator = row.cellIterator();
        if (!cellIterator.hasNext()) {
            return;
        }

        // 默认为 1行高度
        Integer maxHeight = 1;
        while (cellIterator.hasNext()) {
            Cell cell = cellIterator.next();
            switch (cell.getCellTypeEnum()) {
                case STRING:
                    if (cell.getStringCellValue().indexOf("\n") != -1) {
                        int length = cell.getStringCellValue().split("\n").length;
                        maxHeight = Math.max(maxHeight, length);
                    }
                    break;
                default:
                    break;
            }
        }

        row.setHeight((short) (maxHeight * DEFAULT_HEIGHT));
    }
}

2.3 注册器处理

EasyExcel.registerWriteHandler(new CustomCellWriteWeightConfig())
         .registerWriteHandler(new CustomCellWriteHeightConfig());