项目场景：
需求要求生成的excel添加水印，这个还是第一次听到，于是研究了一下。
引入依赖
代码如下：
implementation ('cn.afterturn:easypoi-base:4.5.0') {exclude group: 'com.google.guava', module: 'guava'exclude group: 'org.apache.commons', module: 'commons-compress'}implementation ('org.apache.poi:ooxml-schemas:1.4')
排除的两个因为对代码没有影响，主要是因为有代码漏洞，排除掉就OK了，但是easy POI引入的apache POI并不全，导致无法添加水印，所以必须要引入org.apache.poi:ooxml-schemas:1.4
代码：
直接上代码了。
@Slf4j
public class ExcelWaterMarkUtil {private ExcelWaterMarkUtil() {}public static void excelWaterMark(Workbook workbook, String append, String username){ByteArrayOutputStream os = null;try {//生成水印图片并导出字节流BufferedImage image = createWatermarkImage(append,username);os = new ByteArrayOutputStream();ImageIO.write(image, "png", os);int pictureIdx = workbook.addPicture(os.toByteArray(), Workbook.PICTURE_TYPE_PNG);POIXMLDocumentPart poixmlDocumentPart = (POIXMLDocumentPart) workbook.getAllPictures().get(pictureIdx);//获取每个Sheet表并插入水印for (int i = 0; i < workbook.getNumberOfSheets(); i++) {XSSFSheet sheet1 = (XSSFSheet) workbook.getSheetAt(i);PackagePartName ppn = poixmlDocumentPart.getPackagePart().getPartName();String relType = XSSFRelation.IMAGES.getRelation();//add relation from sheet to the picture dataPackageRelationship pr = sheet1.getPackagePart().addRelationship(ppn, TargetMode.INTERNAL, relType, null);//set background picture to sheetsheet1.getCTWorksheet().addNewPicture().setId(pr.getId());}} catch (Exception e) {log.error("excel文件添加水印异常",e);}finally {if (os != null){try {os.close();}catch (Exception e){log.error("水印图片字节流关闭异常",e);}}}}private static BufferedImage createWatermarkImage(String append, String username) {Graphics2D g = null;try {Font font = new Font("microsoft-yahei", Font.PLAIN, 20);int width = 300, height = 170;BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);g = image.createGraphics();// 背景透明 结束g.setColor(Color.white);g.fillRect(0, 0, width , height);g.setColor(new Color(Integer.parseInt("C5CBCF", 16)));// 设定画笔颜色g.setFont(font);// 设置画笔字体g.shear(0.1, -0.20);// 设定倾斜度// 设置字体平滑g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);String[] textArray = new String[]{ "FRP - " + append, username };int y = 50;for (int i = 0; i < textArray.length; i++) {g.drawString(textArray[i], 0, y);// 画出字符串y = y + font.getSize();}g.drawString(LocalDateTime.now(ZoneId.of(CommonConstant.CHINA_ZONE)).format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")), 0, y);// 画出字符串return image;}finally {g.dispose();// 释放画笔}}}
)
