java excel表格加水印

可以使用 Apache POI 库来操作 Excel 表格并添加水印，具体步骤如下：

1. 导入 Apache POI 库。

2. 创建一个 Excel 文件对象并读取要添加水印的 Excel 表格。

   FileInputStream fis = new FileInputStream("test.xlsx");
   XSSFWorkbook workbook = new XSSFWorkbook(fis);

3. 获取当前工作表对象。

   XSSFSheet sheet = workbook.getSheetAt(0);

4. 创建一个 Drawing 对象并将其添加到当前工作表中。

   XSSFDrawing drawing = sheet.createDrawingPatriarch();

5. 创建一个文本框并设置其位置、大小、内容和样式。

   XSSFSimpleShape shape = drawing.createSimpleShape(new XSSFClientAnchor(0, 0, 0, 0, 0, 0, 1, 1));
   shape.setShapeType(ShapeTypes.TEXT_BOX);
   shape.setFillColor(255, 255, 255);
   shape.setLineStyle(0);
   shape.setLineStyleColor(255, 255, 255);
   shape.setLineWidth(0);
   shape.setNoFill(true);
   shape.setAnchor(new XSSFClientAnchor(0, 0, 0, 0, 0, 0, 10, 10));
   shape.setText("水印内容");
   XSSFRichTextString rts = shape.getRichText();
   XSSFFont font = workbook.createFont();
   font.setColor(IndexedColors.GREY_50_PERCENT.getIndex());
   font.setItalic(true);
   font.setFontHeightInPoints((short) 20);
   rts.applyFont(font);

6. 保存 Excel 文件。

   FileOutputStream fos = new FileOutputStream("test.xlsx");
   workbook.write(fos);
   workbook.close();
   fis.close();
   fos.close();

完整代码如下：

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

import org.apache.poi.ss.usermodel.IndexedColors;
import org.apache.poi.xssf.usermodel.XSSFClientAnchor;
import org.apache.poi.xssf.usermodel.XSSFDrawing;
import org.apache.poi.xssf.usermodel.XSSFFont;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.apache.poi.xssf.usermodel.extensions.XSSFCellBorder.BorderSide;
import org.apache.poi.xssf.usermodel.extensions.XSSFCellBorder;

public class AddWatermarkToExcel {

    public static void main(String[] args) throws Exception {
        FileInputStream fis = new FileInputStream("test.xlsx");
        XSSFWorkbook workbook = new XSSFWorkbook(fis);
        XSSFSheet sheet = workbook.getSheetAt(0);

        XSSFDrawing drawing = sheet.createDrawingPatriarch();
        XSSFSimpleShape shape = drawing.createSimpleShape(new XSSFClientAnchor(0, 0, 0, 0, 0, 0, 1, 1));
        shape.setShapeType(ShapeTypes.TEXT_BOX);
        shape.setFillColor(255, 255, 255);
        shape.setLineStyle(0);
        shape.setLineStyleColor(255, 255, 255);
        shape.setLineWidth(0);
        shape.setNoFill(true);
        shape.setAnchor(new XSSFClientAnchor(0, 0, 0, 0, 0, 0, 10, 10));
        shape.setText("水印内容");
        XSSFRichTextString rts = shape.getRichText();
        XSSFFont font = workbook.createFont();
        font.setColor(IndexedColors.GREY_50_PERCENT.getIndex());
        font.setItalic(true);
        font.setFontHeightInPoints((short) 20);
        rts.applyFont(font);

        FileOutputStream fos = new FileOutputStream("test.xlsx");
        workbook.write(fos);
        workbook.close();
        fis.close();
        fos.close();
    }

}