java pdf加水印的方法

<dependency> <groupId>com.itextpdf.tool</groupId> <artifactId>xmlworker</artifactId> <version>5.5.10</version></dependency><dependency> <groupId>com.itextpdf</groupId> <artifactId>itextpdf</artifactId> <version>5.5.10</version></dependency>

/**  * pdf 加水印  *  * @return  */ public byte[] pdfAddWaterMark(byte[] byes) {  String fileName = UUID.randomUUID().toString() + ".pdf";  String courseFile = "";  try {   // 第二种：获取项目路径 D:/git/daotie/daotie   //生成临时文件 , 读取完删除   File directory = new File("");// 参数为空   courseFile = directory.getCanonicalPath() + "/";  } catch (IOException e) {   e.printStackTrace();  }  byte[] returnBytes = null;  // 待加水印的文件  PdfReader reader = null;  PdfStamper stamper = null;//  ByteArrayOutputStream baos = null;  FileOutputStream os = null;  try {   reader = new PdfReader(byes);   // 加完水印的文件//   baos = new ByteArrayOutputStream();//   stamper = new PdfStamper(reader, baos);   // 加完水印的文件   os = new FileOutputStream(courseFile + fileName);   stamper = new PdfStamper(reader, os);   int total = reader.getNumberOfPages() + 1;   PdfContentByte content;   // BaseFont font = BaseFont.createFont();   BaseFont basefont = BaseFont.createFont("/static/fonts/SIMYOU.TTF", BaseFont.IDENTITY_H, BaseFont.NOT_EMBEDDED);   //这里的字体设置比较关键，这个设置是支持中文的写法   /*BaseFont base = BaseFont.createFont("STSong-Light",     "UniGB-UCS2-H", BaseFont.NOT_EMBEDDED);// 使用系统字体*/   /*//设置透明度   PdfGState gs = new PdfGState();   gs.setFillOpacity(1f);   gs.setStrokeOpacity(1f);*/   PdfContentByte under;   com.itextpdf.text.Rectangle pageRect = null;   // 循环对每页插入水印   for (int i = 1; i < total; i++) {    pageRect = stamper.getReader().getPageSizeWithRotation(i);    // 计算水印X,Y坐标    float x = (float) (pageRect.getWidth() / 1.98);    float y = (float) (pageRect.getHeight() / 2.8);    // 获得PDF最顶层    under = stamper.getOverContent(i);    under.saveState();    // set Transparency    PdfGState gs = new PdfGState();    // 设置透明度为0.2    gs.setFillOpacity(1.f);    under.setGState(gs);    under.restoreState();    under.beginText();    under.setFontAndSize(basefont, pageRect.getHeight() / 17);    under.setColorFill(BaseColor.RED);    // 水印文字成45度角倾斜    System.out.println("width" + pageRect.getWidth());    System.out.println("height" + pageRect.getHeight());    System.out.println("x" + x);    System.out.println("y" + y);    under.showTextAligned(Element.ALIGN_CENTER, "图片仅供预览，不可用于商业用途", x, y, 45);    // 添加水印文字    under.endText();    under.setLineWidth(1f);    under.stroke();   }//   returnBytes = baos.toByteArray();  } catch (IOException e) {   e.printStackTrace();  } catch (DocumentException e) {   e.printStackTrace();  } finally {   try {    stamper.close();    if (os != null) {     os.close();    }    if (reader != null) {     reader.close();    }   } catch (DocumentException e) {    e.printStackTrace();   } catch (IOException e) {    e.printStackTrace();   }  }