SpringBoot应用中PDF添加水印的五种实现方案对比

<dependency>
    <groupId>org.apache.pdfbox</groupId>
    <artifactId>pdfbox</artifactId>
    <version>2.0.24</version>
</dependency>

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.PDPageContentStream;
import org.apache.pdfbox.pdmodel.font.PDType1Font;

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

public class PdfBoxWatermark {
    public static void addWatermark(String inputPath, String outputPath, String watermarkText) throws IOException {
        PDDocument document = PDDocument.load(new File(inputPath));
        for (PDPage page : document.getDocumentCatalog().getPages()) {
            PDPageContentStream contentStream = new PDPageContentStream(document, page, PDPageContentStream.AppendMode.APPEND, true, true);
            contentStream.setFont(PDType1Font.HELVETICA_BOLD, 36);
            contentStream.setNonStrokingColor(200, 200, 200); // 设置透明度
            contentStream.beginText();
            contentStream.newLineAtOffset(100, 100); // 水印位置
            contentStream.showText(watermarkText); // 水印内容
            contentStream.endText();
            contentStream.close();
        }
        document.save(outputPath);
        document.close();
    }
}

public class Main {
    public static void main(String[] args) throws IOException {
        PdfBoxWatermark.addWatermark("original.pdf", "output.pdf", "CONFIDENTIAL");
    }
}

<dependency>
    <groupId>com.itextpdf</groupId>
    <artifactId>itext7-core</artifactId>
    <version>7.2.6</version>
    <type>pom</type>
</dependency>

import com.itextpdf.kernel.pdf.*;
import com.itextpdf.kernel.pdf.canvas.PdfCanvas;

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

public class ITextWatermark {
    public static void addWatermark(String inputPath, String outputPath, String watermarkText) throws IOException {
        PdfReader reader = new PdfReader(new File(inputPath));
        PdfWriter writer = new PdfWriter(outputPath);
        PdfDocument pdfDoc = new PdfDocument(reader, writer);

        for (int i = 1; i <= pdfDoc.getNumberOfPages(); i++) {
            PdfPage page = pdfDoc.getPage(i);
            PdfCanvas canvas = new PdfCanvas(page);
            canvas.beginText();
            canvas.setFontAndSize(PdfFontFactory.createFont(), 60);
            canvas.setTextMatrix(150, 400); // 水印位置
            canvas.showText(watermarkText);
            canvas.endText();
        }
        pdfDoc.close();
    }
}

public class Main {
    public static void main(String[] args) throws IOException {
        ITextWatermark.addWatermark("original.pdf", "output.pdf", "DRAFT");
    }
}

<dependency>
    <groupId>com.aspose</groupId>
    <artifactId>aspose-pdf</artifactId>
    <version>21.4</version>
</dependency>

import com.aspose.pdf.*;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.multipart.MultipartFile;

import java.io.ByteArrayOutputStream;

public class AsposeWatermark {
    public static byte[] addWatermark(MultipartFile file, String watermarkText) throws Exception {
        Document pdfDocument = new Document(file.getInputStream());
        TextStamp textStamp = new TextStamp(watermarkText);
        textStamp.setVerticalAlignment(VerticalAlignment.Center);
        textStamp.setHorizontalAlignment(HorizontalAlignment.Center);
        pdfDocument.getPages().get_Item(1).addStamp(textStamp);

        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        pdfDocument.save(outputStream);
        return outputStream.toByteArray();
    }
}

@PostMapping("/addWatermark")
public ResponseEntity<byte[]> addWatermark(@RequestParam("file") MultipartFile file) throws Exception {
    byte[] result = AsposeWatermark.addWatermark(file, "CONFIDENTIAL");
    return ResponseEntity.ok()
            .header("Content-Disposition", "attachment; filename=\"watermarked.pdf\"")
            .contentType(MediaType.APPLICATION_PDF)
            .body(result);
}

public byte[] addWatermarkViaApi(String apiKey, String filePath, String watermarkText) {
    HttpHeaders headers = new HttpHeaders();
    headers.set("Authorization", "Bearer " + apiKey);
    headers.setContentType(MediaType.MULTIPART_FORM_DATA);

    MultiValueMap<String, Object> body = new LinkedMultiValueMap<>();
    body.add("file", new FileSystemResource(filePath));
    body.add("watermarkText", watermarkText);

    HttpEntity<MultiValueMap<String, Object>> request = new HttpEntity<>(body, headers);
    ResponseEntity<byte[]> response = restTemplate.postForEntity("https://api.example.com/addWatermark", request, byte[].class);
    return response.getBody();
}

public void generatePdfWithTemplate(String templatePath, String outputPath, Map<String, Object> data) {
    // 使用 Thymeleaf 生成 HTML
    String htmlContent = templateEngine.process("template.html", data);
    // 将 HTML 转换为 PDF（需额外依赖如 Flying Saucer）
    ITextRenderer renderer = new ITextRenderer();
    renderer.setDocumentFromString(htmlContent);
    renderer.layout();
    renderer.createPDF(new FileOutputStream(outputPath));
}