springboot 之 使用easyexcel导出数据到多个sheet，动态表头，自动计算列宽

软件版本

springboot 2.7.17

easyexcel 3.0.5

代码

import com.alibaba.excel.enums.CellDataTypeEnum;
import com.alibaba.excel.metadata.Head;
import com.alibaba.excel.metadata.data.CellData;
import com.alibaba.excel.metadata.data.WriteCellData;
import com.alibaba.excel.write.metadata.holder.WriteSheetHolder;
import com.alibaba.excel.write.style.column.AbstractColumnWidthStyleStrategy;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Sheet;
import org.springframework.util.CollectionUtils;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* 自动计算列宽
*/
public class ExcelCellWriteWidthConfig extends AbstractColumnWidthStyleStrategy {
    private final Map<Integer, Map<Integer, Integer>> CACHE = new HashMap<>();

    @Override
    protected void setColumnWidth(WriteSheetHolder writeSheetHolder, List<WriteCellData<?>> cellDataList, Cell cell, Head head, Integer integer, Boolean isHead) {
        boolean needSetWidth = isHead || !CollectionUtils.isEmpty(cellDataList);
        if (needSetWidth) {
            Map<Integer, Integer> maxColumnWidthMap = CACHE.computeIfAbsent(writeSheetHolder.getSheetNo(), k -> new HashMap<>());

            Integer columnWidth = this.dataLength(cellDataList, cell, isHead);
            // 单元格文本长度大于60换行
            if (columnWidth >= 0) {
                if (columnWidth > 60) {
                    columnWidth = 60;
                }
                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 * 2 * 256);
                }
            }
        }
    }

    /**
     * 计算长度
     */
    private Integer dataLength(List<WriteCellData<?>> 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;
                }
            }
        }
    }
}

//动态表头
private List<List<String>> getDynamicHeadList() {
    List<List<String>> headList = new ArrayList<>();
    List<String> head1 = new ArrayList<>();
    head1.add("Group Name");
    headList.add(head1);
    List<String> head2 = new ArrayList<>();
    head2.add("Model Name");
    headList.add(head2);
	return headList;
}
//动态数据
private List<List<String>> getDynamicBodyList() {
    List<List<String>> bodysList = new ArrayList<>();
    for(int i = 0; i < 5; i++){
    	List<String> bodyList = new ArrayList<>();
	    bodyList.add("Group " + i);
	    bodyList.add("Model " + i);
	    bodysList.add(bodyList);
	}
	return bodysList;
}

//写多sheet
final ExcelWriter excelWriter = EasyExcel.write(excel)
		//这里LocalDateTimeConverter类参考上一篇内容
        .registerConverter(new LocalDateTimeConverter())
        .registerWriteHandler(new ExcelCellWriteWidthConfig())
        .build();
WriteSheet writeSheet;
int index = 1；
for (List<List<String>> dataList : ListUtil.split(bodysList, 2)) {
    // 构建sheet对象
    writeSheet = EasyExcel.writerSheet(index,"Sheet"+index++).head(getDynamicHeadList()).build();
    excelWriter.write(getDynamicBodyList(), writeSheet);
}
excelWriter.finish();