java实现给word文件添加水印

一开始使用Aspose.words来给word添加水印，尝试后发现会破坏原文件的格式，故放弃。

经过一系列资料的查找后，确认使用spire.doc for java来实现本功能。

maven添加依赖

根据官方文档引入依赖

<repositories>
    <repository>
        <id>com.e-iceblue</id>
        <url>http://repo.e-iceblue.cn/repository/maven-public/</url>
    </repository>
</repositories>
<dependencies>
    <dependency>
        <groupId>e-iceblue</groupId>
        <artifactId>spire.doc.free</artifactId>
        <version>3.9.0</version>
    </dependency>
</dependencies>

程序核心代码

参考官方demo的基础上，对水印的间距数量进行了优化，使多个水印能够均匀分布在一个页面上。

public class SpireDocUtil {

    public static void addWatermark(String srcFileName, String targetFileName, String watermarkText) {
        //加载示例文档
        Document doc = new Document();
        doc.loadFromFile(srcFileName);

        //页边距
        Section pageSection = doc.getSections().get(0);
        float top = pageSection.getPageSetup().getMargins().getTop();
        float right = pageSection.getPageSetup().getMargins().getRight();
        float bottom = pageSection.getPageSetup().getMargins().getBottom();
        float left = pageSection.getPageSetup().getMargins().getLeft();
        //纸张宽高
        double width = pageSection.getPageSetup().getPageSize().getWidth();
        double height = pageSection.getPageSetup().getPageSize().getHeight();

        //添加水印并设置大小
        ShapeObject shape = new ShapeObject(doc, ShapeType.Text_Plain_Text);
        int shapeWidth = 100;
        int shapeHeight = 12;
        shape.setWidth(shapeWidth);
        shape.setHeight(shapeHeight);
        //设置水印文本内容
        double radian = 2 * Math.PI / 360 * 45;
        shape.setRotation(-45);
        shape.getWordArt().setFontFamily("SimSun");
        shape.getWordArt().setText(watermarkText);
        //设置水印颜色
        shape.setFillColor(Color.lightGray);
        shape.setStrokeColor(Color.lightGray);

        //水印列数
        int colNum = 4;
        //水印行数
        int rowNum = 6;
        //水印真实宽度
        double shapeRealWidth = Math.cos(radian) * (shapeWidth + shapeHeight);
        //水印真实高度
        double shapeRealHeight = Math.sin(radian) * (shapeWidth + shapeHeight);
        //水印中心水平间距
        double xGap = (width - shapeRealWidth * colNum) / (colNum - 1) + shapeRealWidth;
        //水印中心垂直间距
        double yGap = (height - shapeRealHeight * rowNum) / (rowNum - 1) + shapeRealHeight;
        //水印水平起始位置
        double startX = -left - (shapeWidth - shapeRealWidth) / 2;
        //水印水平垂直位置
        double startY = -Math.cos(radian) * shapeHeight;

        Section section;
        HeaderFooter header;
        for (int n = 0; n < doc.getSections().getCount(); n++) {
            section = doc.getSections().get(n);
            //获取section的页眉
            header = section.getHeadersFooters().getHeader();
            Paragraph paragraph;

            if (header.getParagraphs().getCount() > 0) {
                //如果页眉有段落，取它第一个段落
                paragraph = header.getParagraphs().get(0);
            } else {
                //否则新增加一个段落到页眉
                paragraph = header.addParagraph();
            }
            for (int i = 0; i < colNum; i++) {
                for (int j = 0; j < rowNum; j++) {
                    //复制水印并设置多行多列位置
                    shape = (ShapeObject) shape.deepClone();
                    shape.setHorizontalPosition((float) (startX + xGap * i));
                    shape.setVerticalPosition((float) (startY + yGap * j));
                    paragraph.getChildObjects().add(shape);
                }
            }
        }
        //保存文档
        doc.saveToFile(targetFileName, FileFormat.Docx_2013);
    }
}