Java给PDF文档添加水印信息

矫情吗；* 2023-10-12 18:38 28阅读 0赞

在word生成pdf后，或者上传pdf文件，用户希望给pdf文档添加水印信息，具体代码如下

一. 首先pom中需要引入

<dependency>
         <groupId>com.itextpdf</groupId>
         <artifactId>itextpdf</artifactId>
           <version>5.5.13</version>
     </dependency>
     
     <dependency>
         <groupId>com.itextpdf</groupId>
         <artifactId>itext-asian</artifactId>
         <version>5.2.0</version>
     </dependency>

核心代码如下，写在某个 service 下面

public void signPdf(InputStream is, Supplier<OutputStream> os, List<WaterMarkInfoRequest> signList) {
           PdfStamper stamper = null;
           PdfReader reader = null;
           try {
               reader = new PdfReader(is);
               stamper = new PdfStamper(reader, os.get());
               for (WaterMarkInfoRequest s : signList) {
                   TextWaterMarkRequest textWaterMark = s.getTextWaterMark();
                   if (textWaterMark != null) {
                       //添加文字
                       BaseFont baseFont;
                       try {
                           baseFont = BaseFont.createFont("STSong-Light", "UniGB-UCS2-H", BaseFont.NOT_EMBEDDED);
                       } catch (DocumentException | IOException e) {
                           log.info("pdf签名获取字体信息异常:{}", e.getMessage(), e);
                           throw new BusinessException(IO_ERROR.toErrorInfos("pdf签名获取字体信息异常"));
                       }
                       PdfContentByte content = stamper.getOverContent(textWaterMark.getPageNo());
                       PdfGState gState = new PdfGState();
                       //设置透明度
                       gState.setFillOpacity(textWaterMark.getAlpha());
                       content.setGState(gState);
                       content.beginText();
                       //设置字体
                       content.setFontAndSize(baseFont, textWaterMark.getFontSize());
                       //设置颜色
                       content.setColorFill(new BaseColor(0xFF << 24 | Integer.parseInt(textWaterMark.getFontColor(), 16)));
    
                       //设置水印内容和位置
                       content.showTextAligned(Element.ALIGN_MIDDLE, textWaterMark.getText(), textWaterMark.getIntervalVertical(), textWaterMark.getIntervalHorizontal(), 0f);
                       content.endText();
                   }
                   ImageWaterMarkRequest imageWaterMark = s.getImageWaterMark();
                   if (imageWaterMark != null) {
                       //添加图片
                       PdfContentByte content = stamper.getOverContent(imageWaterMark.getPageNo());
                       PdfGState gState = new PdfGState();
                       //设置透明度
                       gState.setFillOpacity(imageWaterMark.getAlpha());
                       //image
                       Image image = Image.getInstance(EncryptUtil.base64DecoderToBytes(imageWaterMark.getBase64Str()));
                       image.setAbsolutePosition(imageWaterMark.getPositionX(), imageWaterMark.getPositionY());
                       if (imageWaterMark.getScaleAbsoluteX() != null && imageWaterMark.getScaleAbsoluteY() != null) {
                           image.scaleToFit(imageWaterMark.getScaleAbsoluteX(), imageWaterMark.getScaleAbsoluteY());
                       } else if (imageWaterMark.getScalePercent() != null && imageWaterMark.getScalePercent() > 0) {
                           image.scalePercent(imageWaterMark.getScalePercent());
                       }
                       content.addImage(image);
                       content.stroke();
                   }
    
               }
    
           } catch (Exception e) {
               e.printStackTrace();
               log.info("添加签名失败：{}", e.getLocalizedMessage(), e);
               WM_WRITE_ERR.throwException();
           } finally {
               if (null != stamper) {
                   try {
                       stamper.close();
                   } catch (Exception e) {
                       log.info("关闭失败：{}", e.getMessage(), e);
                   }
               }
               if (null != reader) {
                   reader.close();
               }
           }
    
       }

用到的实体类

public class ImageWaterMarkRequest{
    
        @ApiModelProperty(value = "需要添加的页码，默认所有页码都添加")
        private Integer pageNo;
        @ApiModelProperty(value = "水平位置  左下角坐标(0,0)")
        private Integer positionX;
        @ApiModelProperty(value = "垂直位置  左下角坐标(0,0)")
        private Integer positionY;
        @ApiModelProperty(value = "指定图像宽度  ")
        private Integer scaleAbsoluteX;
        @ApiModelProperty(value = "指定图像高度 ")
        private Integer scaleAbsoluteY;
        @ApiModelProperty(value = "缩放比例 与指定尺寸冲突 优先使用指定图像尺寸")
        private Integer scalePercent;
        @ApiModelProperty(value = "图片的二进制数据")
        @NotNull
        private String base64Str;
        @ApiModelProperty(value = "透明度  0--1")
        private Float alpha;
    
        @ApiModelProperty(value = "透明度  0--1",hidden = true)
        private Float opacity;
        @ApiModelProperty(value = "是否水印打在最顶层  默认true")
        private Boolean isTop;
    }

public class WaterMarkInfoRequest {
        @ApiModelProperty(value = "文字水印信息")
        private TextWaterMarkRequest textWaterMark;
        @ApiModelProperty(value = "图片水印信息")
        private ImageWaterMarkRequest imageWaterMark;
    }

方法测试

import java.io.InputStream;
    import java.io.OutputStream;
    import java.nio.file.Files;
    import java.nio.file.Paths;
    import java.util.ArrayList;
    
    
    public class PdfWaterMarkServiceImplTest {
    
        public static void main(String[] args) throws Exception {
            InputStream is = Files.newInputStream(Paths.get("/Users/cong/Downloads/a.pdf"));
            OutputStream outputStream = Files.newOutputStream(Paths.get("/Users/cong/Downloads/q-5.pdf"));
            ArrayList<WaterMarkInfoRequest> requests = new ArrayList<>();
    
    
            WaterMarkInfoRequest waterMarkInfo = addSign(1);
            WaterMarkInfoRequest waterMarkInfo2 = addSign(1);
    
    
            requests.add(waterMarkInfo);
            requests.add(waterMarkInfo2);
            //调用你自己服务的pdf水印方法
            new PdfWaterMarkServiceImpl().signPdf(is, () -> outputStream, requests);
            outputStream.close();
        }
    
        private static WaterMarkInfoRequest addSign(Integer pageNum) {
            WaterMarkInfoRequest waterMarkInfo = new WaterMarkInfoRequest();
    
            ImageWaterMarkRequest imageWaterMark = new ImageWaterMarkRequest();
            imageWaterMark.setPageNo(pageNum);
            imageWaterMark.setPositionY(200);
            imageWaterMark.setPositionX(200);
            imageWaterMark.setTop(true);
            imageWaterMark.setAlpha(1.0f);
            imageWaterMark.setBase64Str("图片base64");
    
            waterMarkInfo.setImageWaterMark(imageWaterMark);
    
            TextWaterMarkRequest textWaterMark = new TextWaterMarkRequest();
            textWaterMark.setText("我是一个水印");
            textWaterMark.setRotation(0);
            textWaterMark.setAlpha(1.0f);
            textWaterMark.setFontSize(24);
            textWaterMark.setIntervalHorizontal(10);
            textWaterMark.setIntervalVertical(10);
            textWaterMark.setFontColor("800000");
            textWaterMark.setTop(true);
            textWaterMark.setPageNo(pageNum);
    
            waterMarkInfo.setTextWaterMark(textWaterMark);
    
            return waterMarkInfo;
        }
    
    }