easyExcel设置水印

1、依赖导入

<dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>easyexcel</artifactId>
            <version>3.1.0</version>
        </dependency>
<dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>ooxml-schemas</artifactId>
            <version>1.4</version>
        </dependency>
 

poi的依赖是样式设置需要用到

2、自定义水印处理器

package com.XXX.common.utils.easyexcel;


import com.alibaba.excel.write.handler.SheetWriteHandler;
import com.alibaba.excel.write.metadata.holder.WriteSheetHolder;
import com.alibaba.excel.write.metadata.holder.WriteWorkbookHolder;
import com.XXX.common.exception.CustomException;
import com.XXX.common.utils.SecurityUtils;
import com.XXX.project.system.domain.SysUser;
import lombok.SneakyThrows;
import org.apache.poi.ss.usermodel.Workbook;
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.font.FontRenderContext;
import java.awt.geom.Rectangle2D;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;

/**
 * 添加水印
 *
 * @author wangchen
 * @date 2022/11/30 16:07
 */
public class CustomWaterMarkHandler implements SheetWriteHandler {


    public static ByteArrayOutputStream createWaterMark(String content) throws IOException {
          int width = 400;
        int height = 200;
        // 获取bufferedImage对象
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        String fontType = "微软雅黑";
        int fontStyle = Font.BOLD;
        int fontSize = 18;
        Font font = new Font(fontType, fontStyle, fontSize);
        // 获取Graphics2d对象
        Graphics2D g2d = image.createGraphics();
        image = g2d.getDeviceConfiguration().createCompatibleImage(width, height, Transparency.TRANSLUCENT);
        g2d.dispose();
        g2d = image.createGraphics();
        // 设置字体颜色和透明度，最后一个参数为透明度
        g2d.setColor(new Color(0, 0, 0, 12));
        // 设置字体
        g2d.setStroke(new BasicStroke(1));
        // 设置字体类型  加粗 大小
        g2d.setFont(font);
        // 设置倾斜度
        g2d.rotate(-0.3, (double) image.getWidth() / 2, (double) image.getHeight() / 2);
        FontRenderContext context = g2d.getFontRenderContext();
        Rectangle2D bounds = font.getStringBounds(content, context);
        double x = (width - bounds.getWidth()) / 2;
        double y = (height - bounds.getHeight()) / 2;
        double ascent = -bounds.getY();
        double baseY = y + ascent;
        // 写入水印文字原定高度过小，所以累计写水印，增加高度
        g2d.drawString(content, (int) x, (int) baseY);
        // 设置透明度
        g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER));
        // 释放对象
        g2d.dispose();
        ByteArrayOutputStream os = new ByteArrayOutputStream();
        ImageIO.write(image, "png", os);
        return os;
    }


    public static void putWaterRemarkToExcel(XSSFSheet sheet, byte[] watermarkBytes) {
        XSSFWorkbook workbook = sheet.getWorkbook();
        int watermarkIndex = workbook.addPicture(watermarkBytes, Workbook.PICTURE_TYPE_PNG);
        String relationId = sheet
                .addRelation(null, XSSFRelation.IMAGES, workbook.getAllPictures().get(watermarkIndex))
                .getRelationship().getId();
        sheet.getCTWorksheet().addNewPicture().setId(relationId);
    }

    @Override
    @SneakyThrows
    public void afterSheetCreate(WriteWorkbookHolder writeWorkbookHolder, WriteSheetHolder writeSheetHolder) {
        if (!(writeSheetHolder.getSheet() instanceof XSSFSheet)) {
            throw new CustomException("表格必须是XSSFSheet");
        }
        SysUser user = SecurityUtils.getLoginUser().getUser();
        try (ByteArrayOutputStream waterMark = createWaterMark(user.getUserName())) {
            XSSFSheet sheet = (XSSFSheet) writeSheetHolder.getSheet();
            putWaterRemarkToExcel(sheet, waterMark.toByteArray());
        }
    }
}

3、excel导出工具类

package com.XXX.common.utils.easyexcel;

import cn.hutool.core.date.DatePattern;
import cn.hutool.core.date.DateUtil;
import cn.hutool.core.lang.UUID;
import com.alibaba.excel.EasyExcel;
import com.alibaba.excel.ExcelWriter;
import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.system.ApplicationHome;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.IOException;
import java.net.URLEncoder;
import java.util.function.Consumer;

/**
 * ExcelUtils
 *
 * @author wangchen
 * @date 2022/11/30 12:22
 */
@Slf4j
public class ExcelUtils {

    /**
     * 导出数据
     *
     * @param excelName           excel名字
     * @param excelWriterConsumer 数据
     */
    public static void excelExport(String excelName, Consumer<ExcelWriter> excelWriterConsumer) {
        ServletRequestAttributes requestAttributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
        if (requestAttributes == null) {
            return;
        }
        HttpServletResponse response = requestAttributes.getResponse();
        if (response == null) {
            return;
        }
        // 这里注意 有人反应使用swagger 会导致各种问题，请直接用浏览器或者用postman
        response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
        response.setCharacterEncoding("utf-8");
        // 这里URLEncoder.encode可以防止中文乱码 当然和easyexcel没有关系
        try {
            String fileName = URLEncoder.encode(excelName, "UTF-8").replaceAll("\\+", "%20");
            response.setHeader("Content-disposition", "attachment;filename*=utf-8''" + fileName + ".xlsx");
            // 设置水印要将 inMemory 设置为 true ,但是会有OOM的风险
            ExcelWriter excelWriter = EasyExcel.write(response.getOutputStream()).inMemory(true).build();
            excelWriterConsumer.accept(excelWriter);
            excelWriter.finish();
        } catch (IOException e) {
            log.error("", e);
        }
    }

    /**
     * 导出数据到临时文件
     *
     * @param excelName           excel名字
     * @param excelWriterConsumer 数据,可支持多sheet,自定义样式
     * @return 文件名
     */
    public static String excelExportTemporary(String excelName, Consumer<ExcelWriter> excelWriterConsumer) {
        ApplicationHome h = new ApplicationHome(ExcelExportUtils.class);
        File jarF = h.getSource();
        String path = jarF.getParent() + File.separator + "temporary" + File.separator;
        String now = DateUtil.format(DateUtil.date(), DatePattern.PURE_DATETIME_PATTERN);
        String uid = UUID.randomUUID().toString();
        uid = uid.substring(uid.length() - 4);
        excelName = excelName + now + uid + ".xlsx";
        File file = new File(path + excelName);
        if (!file.getParentFile().exists()) {
            file.getParentFile().mkdirs();
        }
        ExcelWriter excelWriter = EasyExcel.write(file).inMemory(true).build();
        excelWriterConsumer.accept(excelWriter);
        excelWriter.finish();
        return excelName;
    }
}

4、导出示例

 @GetMapping("/exportMonthReview")
    public void exportOnSelf(MonthlyReview monthlyReview) {
        List<MonthReviewDto> monthReviewDtos = monthlyReviewService.selectUserDeptMonthReview(monthlyReview);
        Consumer<ExcelWriter> consumer = excelWriter -> {
            WriteSheet writeSheet = EasyExcel.writerSheet()
                    .registerWriteHandler(new CustomWaterMarkHandler())
                    .head(MonthReviewDto.class)
                    .build();
            excelWriter.write(monthReviewDtos, writeSheet);
        };
        ExcelUtils.excelExport("结果表", consumer);
    }

导出事例之所以用这种方式，是考虑到便于excel的sheet页样式设置

5、水印效果图