EasyExcel 导出 - 自适应图像尺寸

package cn.net.pap.common.excel.handle;
import com.alibaba.excel.metadata.Head;import com.alibaba.excel.metadata.data.ImageData;import com.alibaba.excel.metadata.data.WriteCellData;import com.alibaba.excel.write.handler.CellWriteHandler;import com.alibaba.excel.write.metadata.holder.WriteSheetHolder;import com.alibaba.excel.write.metadata.holder.WriteTableHolder;import org.apache.poi.ss.usermodel.Cell;import org.apache.poi.ss.usermodel.Sheet;import org.apache.poi.ss.util.CellRangeAddress;
import javax.imageio.ImageIO;import java.io.ByteArrayInputStream;import java.util.List;import java.util.Objects;
public class ImageModifyHandler implements CellWriteHandler {
    // 256分之一的字符宽度转换为标准字符宽度。    public static Integer standardCharacterWidth = 256;
    // 7.5是一个估算的字符到像素的转换因子    public static Float character2PixelFactor = 7.5f;
    // 将点转换为英寸，因为1点 = 1/72英寸。    public static Integer pixel2InchFactor = 72;
    // 英寸转换为像素，其中96是常用的DPI（每英寸像素数）值。    public static Integer dpi = 96;
    // 行高与像素的转换因子    public static Float rowHeight2PixelFactor = 1.3333f;

    /**     * 后单元格数据转换     *     * @param writeSheetHolder 写单夹     * @param writeTableHolder 写表夹     * @param cellData         单元格数据     * @param cell             细胞     * @param head             头     * @param relativeRowIndex 相对行索引     * @param isHead           是头     */    @Override    public void afterCellDataConverted(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder,                                       WriteCellData<?> cellData, Cell cell, Head head, Integer relativeRowIndex, Boolean isHead) {        boolean noImageValue = Objects.isNull(cellData) || cellData.getImageDataList() == null || cellData.getImageDataList().size() == 0;        if (Objects.equals(Boolean.TRUE, isHead) || noImageValue) {            return;        }        Sheet sheet = cell.getSheet();        int mergeColumNum = getMergeColumNum(cell, sheet);        int mergeRowNum = getMergeRowNum(cell, sheet);        ImageData imageData = cellData.getImageDataList().get(0);        imageData.setRelativeLastRowIndex(mergeRowNum - 1);        imageData.setRelativeLastColumnIndex(mergeColumNum - 1);
        // 处理图像缩放 - 等比例缩放        try {            ByteArrayInputStream bis = new ByteArrayInputStream(imageData.getImage());            java.awt.image.BufferedImage image = ImageIO.read(bis);            int targetWidth = (int)(sheet.getColumnWidth(cell.getColumnIndex()) / standardCharacterWidth * character2PixelFactor);            int targetHeight = (int)(cell.getRow().getHeightInPoints() / pixel2InchFactor * dpi);
            // 计算图像的缩放比例            double scaleX = (double) targetWidth / image.getWidth();            double scaleY = (double) targetHeight / image.getHeight();            double scale = Math.min(scaleX, scaleY);
            // 计算缩放后的图像大小            int scaledWidth = (int) (image.getWidth() * scale);            int scaledHeight = (int) (image.getHeight() * scale);
            // 计算上下左右四个角的空白            int topPadding = (targetHeight - scaledHeight) / 2;            int bottomPadding = targetHeight - scaledHeight - topPadding;            int leftPadding = (targetWidth - scaledWidth) / 2;            int rightPadding = targetWidth - scaledWidth - leftPadding;
            // 行高（点）= 像素高度 / 1.3333            imageData.setTop((int)(topPadding/rowHeight2PixelFactor));            imageData.setBottom((int)(bottomPadding/rowHeight2PixelFactor));            imageData.setLeft((int)(leftPadding/rowHeight2PixelFactor));            imageData.setRight((int)(rightPadding/rowHeight2PixelFactor));
            bis.close();        } catch (Exception e) {        }
        CellWriteHandler.super.afterCellDataConverted(writeSheetHolder, writeTableHolder, cellData, cell, head, relativeRowIndex, isHead);    }

    /**     * 得到合并行num     *     * @param cell  细胞     * @param sheet 表     * @return int     */    public static int getMergeRowNum(Cell cell, Sheet sheet) {        int mergeSize = 1;        List<CellRangeAddress> mergedRegions = sheet.getMergedRegions();        for (CellRangeAddress cellRangeAddress : mergedRegions) {            if (cellRangeAddress.isInRange(cell)) {                //获取合并的行数                mergeSize = cellRangeAddress.getLastRow() - cellRangeAddress.getFirstRow() + 1;                break;            }        }        return mergeSize;    }
    /**     * 得到合并列num     *     * @param cell  细胞     * @param sheet 表     * @return int     */    public static int getMergeColumNum(Cell cell, Sheet sheet) {        int mergeSize = 1;        List<CellRangeAddress> mergedRegions = sheet.getMergedRegions();        for (CellRangeAddress cellRangeAddress : mergedRegions) {            if (cellRangeAddress.isInRange(cell)) {                //获取合并的列数                mergeSize = cellRangeAddress.getLastColumn() - cellRangeAddress.getFirstColumn() + 1;                break;            }        }        return mergeSize;    }
}