使用 GroupDocs.Watermark for Java 为 PDF 添加水印

<repositories>
   <repository>
      <id>repository.groupdocs.com</id>
      <name>GroupDocs Repository</name>
      <url>https://releases.groupdocs.com/watermark/java/</url>
   </repository>
</repositories>

<dependencies>
   <dependency>
      <groupId>com.groupdocs</groupId>
      <artifactId>groupdocs-watermark</artifactId>
      <version>24.11</version>
   </dependency>
</dependencies>

import com.groupdocs.watermark.Watermarker;

// Create a text watermark with custom settings
TextWatermark textWatermark = new TextWatermark("Protected image", new Font("Arial", 8));

// Align watermark to the center of images
textWatermark.setHorizontalAlignment(HorizontalAlignment.Center);
textWatermark.setVerticalAlignment(VerticalAlignment.Center);

// Rotate the watermark by 45 degrees
textWatermark.setRotateAngle(45);

// Scale watermark based on parent image size
textWatermark.setSizingType(SizingType.ScaleToParentDimensions);
textWatermark.setScaleFactor(1);

// Load an image file as a watermark
ImageWatermark imageWatermark = new ImageWatermark("YOUR_DOCUMENT_DIRECTORY\\ProtectJpg");

// Align image watermark to the center
imageWatermark.setHorizontalAlignment(HorizontalAlignment.Center);
imageWatermark.setVerticalAlignment(VerticalAlignment.Center);

// Rotate the image watermark by -45 degrees
textWatermark.setRotateAngle(-45);

// Scale the image watermark relative to its parent dimensions
imageWatermark.setSizingType(SizingType.ScaleToParentDimensions);
imageWatermark.setScaleFactor(1);

// Open the PDF containing images for watermarking
Watermarker watermarker = new Watermarker("YOUR_DOCUMENT_DIRECTORY\\document.pdf");

// Get a collection of all images within the PDF
WatermarkableImageCollection images = watermarker.getImages();

for (int i = 0; i < images.getCount(); i++) {
    // Check if the image exceeds specific size criteria
    if (images.get_Item(i).getWidth() > 100 && images.get_Item(i).getHeight() > 100) {
        // Alternate between text and image watermarks
        if (i % 2 == 0) {
            images.get_Item(i).add(textWatermark);
        } else {
            images.get_Item(i).add(imageWatermark);
        }
    }
}

// Close the image watermark instance after use
imageWatermark.close();

// Save the PDF with added watermarks in a new file
watermarker.save("YOUR_OUTPUT_DIRECTORY\\document.pdf");

// Close the main watermarker to release document resources
watermarker.close();