原 easyexcel（二十六）：easyexcel导出添加水印

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本文链接：https://www.91mszl.com/zhangwuji/article/details/1479

一：引入pom

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>easyexcel</artifactId>
    <version>3.3.1</version>
</dependency>
<!-- poi 添加水印 -->
<dependency>
    <groupId>org.apache.poi</groupId>
    <artifactId>ooxml-schemas</artifactId>
    <version>1.4</version>
</dependency>

二：代码

@GetMapping("/download")
    public void download(HttpServletResponse response) throws IOException {
        String fileName = System.currentTimeMillis() + ".xlsx";
        response.reset();
        response.addHeader("Content-Disposition", "attachment; filename=\"" + fileName + "\"");
        OutputStream os=response.getOutputStream();

        List<UserInfo> dataList=new ArrayList<>();
        UserInfo u1=new UserInfo();
        u1.setName("张无忌");
        u1.setAge(18);
        u1.setAddress("上海火车站");

        UserInfo u2=new UserInfo();
        u2.setName("赵敏");
        u2.setAge(18);
        u2.setAddress("上海火车站");

        dataList.add(u1);
        dataList.add(u2);

        List<List<String>> headList=new ArrayList<>();
        headList.add(Lists.newArrayList("姓名"));
        headList.add(Lists.newArrayList("年龄"));
        headList.add(Lists.newArrayList("地址"));

        EasyExcel.write(os).head(headList).sheet("用户信息").registerWriteHandler(new WaterMarkHandler("91mszl.com")).doWrite(dataList);
    }

三：水印工具类

package com.mszl.business.common.utils;

import cn.hutool.core.util.ReflectUtil;
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.SneakyThrows;
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.ss.usermodel.Workbook;
import org.apache.poi.xssf.streaming.SXSSFSheet;
import org.apache.poi.xssf.streaming.SXSSFWorkbook;
import org.apache.poi.xssf.usermodel.XSSFPictureData;
import org.apache.poi.xssf.usermodel.XSSFRelation;
import org.apache.poi.xssf.usermodel.XSSFSheet;

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;

public class WaterMarkHandler implements SheetWriteHandler {

    private final String water_mark;

    public WaterMarkHandler(String water_mark) {
        this.water_mark=water_mark;
    }

    @Override
    public void beforeSheetCreate(WriteWorkbookHolder writeWorkbookHolder, WriteSheetHolder writeSheetHolder) {

    }
    
    @SneakyThrows
    @Override
    public void afterSheetCreate(WriteWorkbookHolder writeWorkbookHolder, WriteSheetHolder writeSheetHolder) {
        try (ByteArrayOutputStream waterMark = createWaterMark(water_mark)){
            SXSSFSheet sheet = (SXSSFSheet) writeSheetHolder.getSheet();
            putWaterRemarkToExcel(sheet, waterMark.toByteArray());
        }
    }

    public static ByteArrayOutputStream createWaterMark(String content) throws IOException {
        int width = 200;
        int height = 150;
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); // 获取bufferedImage对象
        String fontType = "微软雅黑";
        int fontStyle = Font.BOLD;
        int fontSize = 20;
        Font font = new Font(fontType, fontStyle, fontSize);
        Graphics2D g2d = image.createGraphics(); // 获取Graphics2d对象
        image = g2d.getDeviceConfiguration().createCompatibleImage(width, height, Transparency.TRANSLUCENT);
        g2d.dispose();
        g2d = image.createGraphics();
        g2d.setColor(new Color(0, 0, 0, 20)); // 设置字体颜色和透明度，最后一个参数为透明度
        g2d.setStroke(new BasicStroke(1)); // 设置字体
        g2d.setFont(font); // 设置字体类型 加粗 大小
        g2d.rotate(-0.5, (double) image.getWidth() / 2, (double) image.getHeight() / 2); // 设置倾斜度
        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;
    }

    /**
     为Excel打上水印工具函数
     @param sheet excel sheet
     @param bytes 水印图片字节数组
     */
    public static void putWaterRemarkToExcel(SXSSFSheet sheet, byte[] bytes) {
        // add relation from sheet to the picture data
        SXSSFWorkbook workbook = sheet.getWorkbook();
        XSSFSheet shReflect = (XSSFSheet) ReflectUtil.getFieldValue(sheet, "_sh");
        int pictureIdx = workbook.addPicture(bytes, Workbook.PICTURE_TYPE_PNG);
        XSSFPictureData xssfPictureData = (XSSFPictureData) workbook.getAllPictures().get(pictureIdx);
        PackagePartName ppn = xssfPictureData.getPackagePart().getPartName();
        PackageRelationship pr = shReflect.getPackagePart().addRelationship(ppn, TargetMode.INTERNAL, XSSFRelation.IMAGES.getRelation(), null);
        //set background picture to sheet
        shReflect.getCTWorksheet().addNewPicture().setId(pr.getId());
    }
    

}

四：效果图