利用PDFBOX给PDF文件添加水印

package com.test;

import org.apache.pdfbox.pdmodel.*;
import org.apache.pdfbox.pdmodel.font.PDFont;
import org.apache.pdfbox.pdmodel.font.PDType0Font;
import org.apache.pdfbox.pdmodel.graphics.state.PDExtendedGraphicsState;
import org.apache.pdfbox.util.Matrix;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

public class TestWaterMark3 {
    public static void main(String[] args) {
        File tempFile = new File("C://Users//Admin//Desktop//凭证 - 副本.pdf");
 String waterMark = "我是测试水印";
 float fontSize = 13;
 int[] color = {0, 200, 0};
 int rowSpace = 150;
 int colSpace = 150;
 try {
            waterMarkUtil(tempFile, waterMark, fontSize, color, rowSpace, colSpace);
 } catch (IOException e) {
            System.out.println("水印渲染异常：" + e);
 }
    }

    /**
 * 给文件添加水印
 *
 * @param tempFile 需要添加水印的文件
 * @param waterMark 水印文字
 * @param fontSize 字体大小
 * @param color 字体颜色：{r, g, b}
 * @param rowSpace 行间距，大中小分别对应150/100/50
 * @param colSpace 列间距，大中小分别对应150/100/50
 * @throws IOException 异常
 */
 private static void waterMarkUtil(File tempFile, String waterMark, float fontSize, int[] color, int rowSpace, int colSpace) throws IOException {
        // 加载PDF文件
 PDDocument document = PDDocument.load(tempFile);
 document.setAllSecurityToBeRemoved(true);

 // 遍历PDF文件，在每一页加上水印
 for (PDPage page : document.getPages()) {
            PDPageContentStream stream = new PDPageContentStream(document, page, PDPageContentStream.AppendMode.APPEND, true, true);

 // 加载水印字体
 PDFont font = PDType0Font.load(document, new FileInputStream("C://Users//Admin//Desktop//锐字工房云字库大黑GBK.ttf"), true);

 PDExtendedGraphicsState r = new PDExtendedGraphicsState();

 // 设置透明度
 r.setNonStrokingAlphaConstant(0.2f);
 r.setAlphaSourceFlag(true);
 stream.setGraphicsStateParameters(r);

 // 设置水印字体颜色
 if (color.length == 3) {
                stream.setNonStrokingColor(color[0], color[1], color[2]);
 }
            stream.beginText();
 stream.setFont(font, fontSize);
 stream.newLineAtOffset(0, -15);

 // 获取PDF页面大小
 float pageHeight = page.getMediaBox().getHeight();
 float pageWidth = page.getMediaBox().getWidth();

 // 根据纸张大小添加水印，30度倾斜
 for (int h = 10; h < pageHeight; h = h + rowSpace) {
                for (int w = - 10; w < pageWidth; w = w + colSpace) {
                    stream.setTextMatrix(Matrix.getRotateInstance(0.3, w, h));
 stream.showText(waterMark);
 }
            }

            // 结束渲染，关闭流
 stream.endText();
 stream.restoreGraphicsState();
 stream.close();
 }
        document.save(tempFile);
 }
}