java给word添加文字水印

可以使用Apache POI库来实现在Word文档中添加文字水印。

下面是一个示例代码：

import java.io.FileInputStream;
import java.io.FileOutputStream;
import org.apache.poi.xwpf.usermodel.XWPFDocument;
import org.apache.poi.xwpf.usermodel.XWPFParagraph;
import org.apache.poi.xwpf.usermodel.XWPFRun;
import org.apache.poi.xwpf.usermodel.XWPFHeader;
import org.apache.poi.xwpf.usermodel.XWPFHeaderFooterPolicy;
import org.apache.poi.xwpf.usermodel.XWPFHeaderFooter;
import org.apache.poi.xwpf.usermodel.ParagraphAlignment;
import org.apache.poi.xwpf.usermodel.VerticalAlign;

public class AddWatermarkToWord {
    public static void main(String[] args) throws Exception {
        String inputFile = "input.docx";
        String outputFile = "output.docx";
        String watermarkText = "Confidential";

        // 读取Word文档
        XWPFDocument document = new XWPFDocument(new FileInputStream(inputFile));

        // 添加水印到页眉
        XWPFHeaderFooterPolicy headerPolicy = document.getHeaderFooterPolicy();
        if (headerPolicy == null) {
            headerPolicy = new XWPFHeaderFooterPolicy(document);
            document.createHeaderFooterPolicy();
        }
        XWPFHeader header = headerPolicy.createHeader(XWPFHeaderFooterPolicy.DEFAULT);
        XWPFParagraph paragraph = header.createParagraph();
        paragraph.setAlignment(ParagraphAlignment.CENTER);
        XWPFRun run = paragraph.createRun();
        run.setText(watermarkText);
        run.setBold(true);
        run.setFontSize(40);
        run.setItalic(true);
        run.setColor("BFBFBF");
        run.setVerticalAlignment(VerticalAlign.BOTTOM); // 放置在页眉底部

        // 保存Word文档
        FileOutputStream out = new FileOutputStream(outputFile);
        document.write(out);
        out.close();
        document.close();
    }
}

需要注意的是，Apache POI库的版本需要和Word文档的格式相对应。例如，如果Word文档是.docx格式，则需要使用poi-ooxml库。