easyexcel实现导出添加文字水印

引入jar包

由于easyexcel没有引入ooxml-schemas包，所以需要额外添加。

1. <dependency>
2.     <groupId>com.alibaba</groupId>
3.     <artifactId>easyexcel</artifactId>
4.     <version>2.2.6</version>
5. </dependency>
7. <dependency>
8.     <groupId>org.apache.poi</groupId>
9.     <artifactId>ooxml-schemas</artifactId>
10.     <version>1.4</version>
11. </dependency>
13. <dependency>
14.     <groupId>cn.hutool</groupId>
15.     <artifactId>hutool-all</artifactId>
16. </dependency>

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新增水印配置类和WriteHandler

新增水印配置类

1. @Data
2. public class Watermark {
4.     /**
5.      * 水印内容
6.      */
7.     private String content = "";
9.     /**
10.      * 画笔颜色. eg:#C5CBCF
11.      */
12.     private String color = "#C5CBCF";
14.     /**
15.      * 字体颜色
16.      */
17.     private Font font = new Font("microsoft-yahei", Font.PLAIN, 20);
19.     /**
20.      * 水印宽、高
21.      */
22.     private int width = 300;
23.     private int height = 100;
25.     /**
26.      * 倾斜度
27.      */
28.     private double shear1 = 0.1;
29.     private double shear2 = -0.26;
31.     /**
32.      * 字体的y轴位置
33.      */
34.     private int yAxis = 50;
36. }

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新增WriteHandler

注意：此方法只适用于XSSFWorkbook类，easyexcel默认使用的是SXSSFWorkbook类，在使用easyexcel导出时需要设置为inMemory模式，否则会抛出类型转换异常。

1. public class CustomWaterMarkHandler implements SheetWriteHandler {
3.     private final Watermark watermark;
5.     public CustomWaterMarkHandler(Watermark watermark) {
6.         this.watermark = watermark;
7.     }
9.     @Override
10.     public void beforeSheetCreate(WriteWorkbookHolder writeWorkbookHolder, WriteSheetHolder writeSheetHolder) {
12.     }
14.     @Override
15.     public void afterSheetCreate(WriteWorkbookHolder writeWorkbookHolder, WriteSheetHolder writeSheetHolder) {
16.         try {
17.             BufferedImage bufferedImage = createWatermarkImage();
18.             setWaterMarkToExcel((XSSFWorkbook) writeWorkbookHolder.getWorkbook(), bufferedImage);
19.         } catch (Exception e) {
20.             throw new RuntimeException("添加水印出错");
21.         }
22.     }
24.     private BufferedImage createWatermarkImage() {
25.         final Font font = watermark.getFont();
26.         final int width = watermark.getWidth();
27.         final int height = watermark.getHeight();
29.         String[] textArray = watermark.getContent().split(",");
30.         BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
31.         // 背景透明 开始
32.         Graphics2D g = image.createGraphics();
33.         image = g.getDeviceConfiguration().createCompatibleImage(width, height, Transparency.TRANSLUCENT);
34.         g.dispose();
35.         // 背景透明 结束
36.         g = image.createGraphics();
37.         // 设定画笔颜色
38.         g.setColor(new Color(Integer.parseInt(watermark.getColor().substring(1), 16)));
39.         // 设置画笔字体
40.         g.setFont(font);
41.         // 设定倾斜度
42.         g.shear(watermark.getShear1(), watermark.getShear2());
44.         // 设置字体平滑
45.         g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
47.         int y = watermark.getYAxis();
48.         for (String s : textArray) {
49.             // 从画框的y轴开始画字符串.假设电脑屏幕中心为0，y轴为正数则在下方
50.             g.drawString(s, 0, y);
51.             y = y + font.getSize();
52.         }
54.         // 释放画笔
55.         g.dispose();
56.         return image;
57.     }
59.     private void setWaterMarkToExcel(XSSFWorkbook workbook, BufferedImage bfi) {
60.         //将图片添加到工作簿
61.         int pictureIdx = workbook.addPicture(ImgUtil.toBytes(bfi, ImgUtil.IMAGE_TYPE_PNG), Workbook.PICTURE_TYPE_PNG);
62.         //建立 sheet 和 图片 的关联关系
63.         XSSFPictureData xssfPictureData = workbook.getAllPictures().get(pictureIdx);
64.         for (int i = 0; i < workbook.getNumberOfSheets(); i++) {
65.             XSSFSheet xssfSheet = workbook.getSheetAt(i);
66.             PackagePartName packagePartName = xssfPictureData.getPackagePart().getPartName();
67.             PackageRelationship packageRelationship = xssfSheet.getPackagePart()
68.                     .addRelationship(packagePartName, TargetMode.INTERNAL, XSSFRelation.IMAGES.getRelation(), null);
69.             //添加水印到工作表
70.             xssfSheet.getCTWorksheet().addNewPicture().setId(packageRelationship.getId());
71.         }
72.     }
73. }

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测试

1. //水印配置
2. Watermark watermark = new Watermark();
3. watermark.setContent("测试文字水印");
4. watermark.setWidth(500);
5. watermark.setHeight(200);
6. watermark.setYAxis(200);
8. //导出
9. EasyExcel.write(outputStream, Test.class)
10.         .inMemory(true)
11.         .sheet("sheet1")
12.         .registerWriteHandler(new CustomWaterMarkHandler(watermark))
13.         .doWrite(Collections.singletonList(new Test()));

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