将带有Apache POI的水印添加到已有标头的docx

import org.apache.poi.xwpf.usermodel.*;

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

public class AddWatermarkToDocx {
    public static void main(String[] args) {
        try {
            // 打开已有的.docx文件
            FileInputStream fileInputStream = new FileInputStream("path/to/existing.docx");
            XWPFDocument document = new XWPFDocument(fileInputStream);

            // 创建水印
            XWPFHeader header = document.createHeader(HeaderFooterType.DEFAULT);
            XWPFParagraph watermarkParagraph = header.createParagraph();
            XWPFRun watermarkRun = watermarkParagraph.createRun();
            watermarkRun.setText("Watermark Text");
            watermarkRun.setFontSize(72);

            // 添加水印到标头
            // 可以根据需要设置水印的样式和位置

            // 保存文档
            FileOutputStream fileOutputStream = new FileOutputStream("path/to/modified.docx");
            document.write(fileOutputStream);

            // 关闭流
            fileInputStream.close();
            fileOutputStream.close();
            document.close();

            System.out.println("Watermark added successfully.");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}