public static boolean waterMark(String inputFile,
                                    String outputFile, String waterMarkName)throws IOException {
        try {
            //inputFile = new String(inputFile.getBytes("UTF-8"),"UTF-8");
            BaseFont base = BaseFont.createFont("STSong-Light",
                    
 
"UniGB-UCS2-H", BaseFont.NOT_EMBEDDED);// 使用系統字體
            String inputFileName = inputFile.substring(inputFile.lastIndexOf("/")+1);

            inputFileName = URLEncoder.encode(inputFileName, "utf-8");
            inputFileName = StringUtils.replace(inputFileName, "+", "%20");
            //inputFileName.replace("+","%20");
            
 
//response.addHeader("Content-Disposition", "attachment;inputFileName=" + inputFileName);
            //inputFileName = URLEncoder.encode(inputFileName, "utf-8").replaceAll("\\+", "%2B").replaceAll("\\s", " ");
            //inputFileName = URLDecoder.decode(inputFileName, "utf-8");
            //inputFileName = new String(inputFileName.getBytes(),"ISO-8859-1");
            
 
//處理文件名有中文問題
//            try {
//                if (request.getHeader("User-Agent").toUpperCase().indexOf("MSIE") > 0) {
//                    inputFileName= URLEncoder.encode(inputFileName, "UTF-8");
//                } else {
//                    inputFileName= new String(inputFileName.getBytes(),"ISO-8859-1");
//                }
//            } catch (UnsupportedEncodingException e) {
//                e.printStackTrace();
//            }
//            //最後加雙引號處理名稱中間有空格問題
//            response.setHeader("Content-Disposition","attachment;filename=\""+inputFileName+"\"");
            inputFile = inputFile.substring(0,inputFile.lastIndexOf("/"))+"/"+inputFileName;
            URL url = new URL(inputFile);
            InputStream file = url.openStream();
            PdfReader reader = new PdfReader(file);
            System.out.print("reader"+reader);
            File fileOut = new File(outputFile);
            if (!fileOut.exists()) {
                // 先得到文件的上級目錄，並創建上級目錄，在創建文件
                fileOut.getParentFile().mkdir();
                fileOut.createNewFile();
            }
            //Field f = PdfReader.class.getDeclaredField("ownerPasswordUsed");
            //f.setAccessible(true);
            //f.set(reader, Boolean.TRUE);
            PdfStamper stamper = new PdfStamper(reader, new BufferedOutputStream(new FileOutputStream(fileOut)));
            //這裏的字體設置比較關鍵，這個設置是支持中文的寫法
            int total = reader.getNumberOfPages() + 1;

            PdfContentByte under;
            Rectangle pageRect = null;
            String [] content = waterMarkName.split("\r\n");
            for (int i = 1; i < total; i++) {
                pageRect = stamper.getReader().
                        getPageSizeWithRotation(i);
                // 計算水印X,Y坐標
                float x = pageRect.getWidth()/2;
                float y = pageRect.getHeight()/2;
                // 獲得PDF最頂層
                under = stamper.getOverContent(i);
                under.saveState();
                // set Transparency
                PdfGState gs = new PdfGState();
                // 設置透明度為0.2
                gs.setFillOpacity(0.1f);
                under.setGState(gs);
                under.restoreState();
                under.beginText();
                under.setFontAndSize(base, 55);
                under.setColorFill(BaseColor.GRAY);

                // 水印文字成35度角傾斜
                under.showTextAligned(Element.ALIGN_CENTER
                        ,content[0], x,
                        y, 35);
                under.showTextAligned(Element.ALIGN_CENTER
                        ,content[1], x+30,
                        y-50, 35);
                // 添加水印文字
                under.endText();
                under.setLineWidth(1f);
                under.stroke();
            }
            stamper.close();
            file.close();
            return true;
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }

pdf文件下載水印添加的中文與空格問題解決