POM

<dependency><groupId>org.apache.pdfbox</groupId><artifactId>pdfbox</artifactId><version>2.0.27</version>
</dependency>

代码：

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.PDPageContentStream;
import org.apache.pdfbox.pdmodel.font.PDFont;
import org.apache.pdfbox.pdmodel.font.PDType0Font;
import org.apache.pdfbox.pdmodel.graphics.image.PDImageXObject;
import org.apache.pdfbox.pdmodel.graphics.state.PDExtendedGraphicsState;
import org.apache.pdfbox.util.Matrix;import java.awt.*;
import java.io.File;public class Test1 {public static void main(String[] args) {// 原始文件路径String sourcePath = "D:\\poi\\11.pdf";// 去c://windows/font下赋值去String fontFilePath = "D:\\poi\\simhei.ttf";String waterMarkText = "水印文字";// log图片的位置String logoFilePath = "D:\\poi\\logo.jpeg";// 输出的PDF文件路径String pdfFile = "D:\\poi\\11-new" + System.currentTimeMillis() + ".pdf";addWaterRemark(sourcePath, pdfFile, fontFilePath, waterMarkText, logoFilePath);}public static void addWaterRemark(String sourcePath, String pdfFile, String fontFilePath, String waterMarkText, String logoFilePath) {try {// 读取原始 PDF 文件PDDocument doc = PDDocument.load(new File(sourcePath));doc.setAllSecurityToBeRemoved(true);//必须是ttf字体PDFont font = PDType0Font.load(doc, new File(fontFilePath));PDImageXObject logoImage = PDImageXObject.createFromFile(logoFilePath, doc);float logoImageWidth = logoImage.getWidth();float logoImageHeight = logoImage.getHeight();float maxX;float maxY;float tempX;float tempY;float xStepLength = 300f;float yStepLength = 200f;float startX = 100f;float startY = 100f;PDPageContentStream cs;// 透明度PDExtendedGraphicsState r0 = new PDExtendedGraphicsState();r0.setNonStrokingAlphaConstant(0.2f);r0.setAlphaSourceFlag(true);for (PDPage page : doc.getPages()) {maxX = page.getBBox().getUpperRightX();maxY = page.getBBox().getUpperRightX();cs = new PDPageContentStream(doc, page, PDPageContentStream.AppendMode.APPEND, true, true);cs.setGraphicsStateParameters(r0);cs.setNonStrokingColor(new Color(200, 200, 200));cs.setFont(font, 36f);// 添加图片，不能在beginText和endText之间加cs.drawImage(logoImage, (maxX - logoImageWidth) / 2, maxY / 2, logoImageWidth * 1.5f, logoImageHeight * 1.5f);cs.beginText();tempX = startX;while (tempX < maxX) {tempY = startY;while (tempY < maxY) {cs.setTextMatrix(Matrix.getRotateInstance(45, tempX, tempY));cs.showText(waterMarkText);tempY += yStepLength;}tempX += xStepLength;}cs.endText();// 关闭流cs.close();}// 保存修改后的 PDF 文件doc.save(new File(pdfFile));doc.close();} catch (Exception e) {e.printStackTrace();}}
}