java使用POI生成pdf文件添加自定义水印-Go服务器开发

在Java中使用Apache POI生成PDF文件并添加自定义水印，通常需要结合Apache PDFBox库来实现。POI本身主要用于处理Microsoft Office格式的文档，但可以通过PDFBox来操作PDF文件。

下面是一个简单的示例，演示如何使用Apache POI创建Excel文件，然后将其转换为PDF，并最终添加自定义水印：

依赖库

首先，你需要在你的项目中引入以下依赖（如果你使用Maven，可以在pom.xml中添加）：

<dependency>
    <groupId>org.apache.poi</groupId>
    <artifactId>poi-ooxml</artifactId>
    <version>5.2.3</version> <!-- 请根据最新版本进行替换 -->
</dependency>
<dependency>
    <groupId>org.apache.pdfbox</groupId>
    <artifactId>pdfbox</artifactId>
    <version>2.0.24</version> <!-- 请根据最新版本进行替换 -->
</dependency>

示例代码

下面的代码展示了如何创建Excel文档并转换为PDF，以及如何给PDF添加水印。

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.graphics.image.PDImageXImage;
import org.apache.pdfbox.pdmodel.common.PDRectangle;

import java.io.*;

public class WatermarkExample {

    public static void main(String[] args) {
        try {
            // Step 1: Create an Excel file
            Workbook workbook = new XSSFWorkbook();
            Sheet sheet = workbook.createSheet("Sheet1");
            Row row = sheet.createRow(0);
            Cell cell = row.createCell(0);
            cell.setCellValue("Hello, World!");
            
            // Save the Excel file
            File excelFile = new File("example.xlsx");
            try (FileOutputStream outputStream = new FileOutputStream(excelFile)) {
                workbook.write(outputStream);
            }
            
            workbook.close();

            // Step 2: Convert Excel to PDF (This part is simplified; use a library for actual conversion)
            // Here you would convert the generated Excel to PDF using a suitable library or method
            
            PDDocument document = new PDDocument();
            PDPage page = new PDPage(PDRectangle.A4);
            document.addPage(page);

            // Example of adding text (you can enhance this to format it like your Excel content)
            
			// Load the created PDF from the path 
			// Or create a sample PDF content as above 
			
			// Step 3: Add watermark
			String watermarkText = "CONFIDENTIAL";
			
			// Add watermark logic here using PDFBox API (for simplicity only a text watermark shown)
		    addWatermark(document, page, watermarkText);

		    // Save the PDF with the watermark
		    document.save(new File("output_with_watermark.pdf"));
		    document.close();

        } catch (IOException e) {
           e.printStackTrace();
        }
    }

    private static void addWatermark(PDDocument document, PDPage page, String text) throws IOException {
        // This is a simple implementation that overlays text as a watermark.
        PDPageContentStream contentStream = new PDPageContentStream(document, page, true, true);
        contentStream.beginText();
        contentStream.setFont(PDType1Font.HELVETICA_BOLD_OBLIQUE, 60); // Set font and size
        contentStream.setNonStrokingColor(200, 200, 200); // Light gray color for watermark
        contentStream.newLineAtOffset(100, 300); // Position of watermark on the page
        contentStream.showText(text);
        contentStream.endText();
        
        contentStream.close();
    }
}