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实现easyexcel中的SheetWriteHandler，在afterSheetCreate中添加水印

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刘哲贤 2024-04-16 22:43:43 +08:00
parent ce8db0389e
commit 48d108d4e6
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smart-admin-api/sa-admin/src/main/java/net/lab1024/sa/admin/util/excel/CustomWaterMarkHandler.java Normal file
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package net.lab1024.sa.admin.util.excel;
import com.alibaba.excel.write.handler.SheetWriteHandler;
import com.alibaba.excel.write.metadata.holder.WriteSheetHolder;
import com.alibaba.excel.write.metadata.holder.WriteWorkbookHolder;
import lombok.extern.slf4j.Slf4j;
import org.apache.poi.openxml4j.opc.PackagePartName;
import org.apache.poi.openxml4j.opc.PackageRelationship;
import org.apache.poi.openxml4j.opc.TargetMode;
import org.apache.poi.xssf.usermodel.XSSFPictureData;
import org.apache.poi.xssf.usermodel.XSSFRelation;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
/**
*
* @author liuzhexian
* @since 2024-04-16
* @email 1037512352@qq.com
*/
@Slf4j
public class CustomWaterMarkHandler implements SheetWriteHandler {
private final Watermark watermark;
public CustomWaterMarkHandler(Watermark watermark) {
this.watermark = watermark;
}
@Override
public void afterSheetCreate(WriteWorkbookHolder writeWorkbookHolder, WriteSheetHolder writeSheetHolder) {
BufferedImage bufferedImage = createWatermarkImage();
XSSFWorkbook workbook = (XSSFWorkbook) writeSheetHolder.getParentWriteWorkbookHolder().getWorkbook();
try {
// 添加水印的具体操作
addWatermarkToSheet(workbook, bufferedImage);
} catch (Exception e) {
log.error("添加水印出错:", e);
}
}
/**
* 创建水印图片
*
* @return
*/
private BufferedImage createWatermarkImage() {
// 获取水印相关参数
Font font = watermark.getFont();
int width = watermark.getWidth();
int height = watermark.getHeight();
Color color = watermark.getColor();
String text = watermark.getContent();
// 创建带有透明背景的 BufferedImage
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
Graphics2D g = image.createGraphics();
// 设置画笔字体、平滑、颜色
g.setFont(font);
g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g.setColor(color);
// 计算水印位置和角度
int y = watermark.getYAxis();
int x = watermark.getXAxis();
AffineTransform transform = AffineTransform.getRotateInstance(Math.toRadians(-watermark.getAngle()), 0, y);
g.setTransform(transform);
// 绘制水印文字
g.drawString(text, x, y);
// 释放资源
g.dispose();
return image;
}
private void addWatermarkToSheet(XSSFWorkbook workbook, BufferedImage watermarkImage) {
try (ByteArrayOutputStream os = new ByteArrayOutputStream()) {
ImageIO.write(watermarkImage, "png", os);
int pictureIdx = workbook.addPicture(os.toByteArray(), XSSFWorkbook.PICTURE_TYPE_PNG);
XSSFPictureData pictureData = workbook.getAllPictures().get(pictureIdx);
for (int i = 0; i < workbook.getNumberOfSheets(); i++) {
// 获取每个Sheet表
XSSFSheet sheet = workbook.getSheetAt(i);
PackagePartName ppn = pictureData.getPackagePart().getPartName();
String relType = XSSFRelation.IMAGES.getRelation();
PackageRelationship pr = sheet.getPackagePart().addRelationship(ppn, TargetMode.INTERNAL, relType, null);
sheet.getCTWorksheet().addNewPicture().setId(pr.getId());
}
} catch (Exception e) {
// 处理ImageIO.write可能抛出的异常
log.error("添加水印图片时发生错误", e);
}
}
}