使用iText为PDF加图片水印

Maven依赖：

<dependency>
<groupId>com.sankuai.mms</groupId>
<artifactId>mms-boot</artifactId>
<version>1.0.3</version>
</dependency>
Java代码：

替换watermark_backgroud.png为本地图片即可。

public static void imageWatermark(String inputPath, String outputPath) throws IOException, DocumentException {

PdfReader reader = new PdfReader(inputPath);
PdfStamper stamp = new PdfStamper(reader, new FileOutputStream(outputPath));
PdfGState gs1 = new PdfGState();
gs1.setFillOpacity(0.1f);

Image image = Image.getInstance(IOUtils.toByteArray(new FileInputStream(System.getProperty("user.dir") + "/src/main/webapp/WEB-INF/resources/image/watermark_backgroud.png")));
int n = reader.getNumberOfPages();
for(int i = 1; i <= n; i++) {
PdfContentByte pdfContentByte = stamp.getOverContent(i);
pdfContentByte.setGState(gs1);

image.setAbsolutePosition(100, 300);
pdfContentByte.addImage(image);
}

stamp.close();
reader.close();
}
效果