前段時間研究了圖片上傳新增水印的效果，現在貼出來供大家參考參考。

/**
 * 圖片上傳，新增水印
* @param request
* @param params
* @param values
* @return
* @throws Exception
 * @author LLJ
 * @date 2016/12/16
 */
public static List<Map<String, Object>> newUpload(HttpServletRequest request,
      String[] params, Map<String, Object[]> values) throws 
 
Exception {


   List<Map<String, Object>> result = new ArrayList<Map<String, Object>>();

   MultipartHttpServletRequest mRequest = (MultipartHttpServletRequest) request;
   Map<String, MultipartFile> fileMap = mRequest.getFileMap();

   String relativePath = FileOperateUtil.UPLOADDIR    
 
+ DateUtils.dateStr7(new Date()) + "/";
   logger.info("圖片relativePath:"+relativePath);
   String uploadDir = request.getSession().getServletContext().getRealPath("/") + "/" + relativePath;
   logger.info("圖片uploadDir:"+uploadDir);
   File file = new File(uploadDir);
   if (!file.exists()) {
      file.mkdirs();
   }

   String fileName = null
 
;
   int i = 0;
   for (Iterator<Map.Entry<String, MultipartFile>> it = fileMap.entrySet().iterator(); it.hasNext(); i++) {
      Map<String, Object> map = new HashMap<String, Object>();
      map.put("success", true);
      Map.Entry<String, MultipartFile> entry = it.next();
      MultipartFile mFile = entry.getValue();
      //判斷檔案格式 和 檔案大小
if(mFile.getSize()/1024D>NEW_LIMIT_SIZE){
         map.put("success", false);
         map.put("msg", "圖片僅支援小於3M的jpg、 png.格式");
         result.add(map);
         continue;
      }
      //獲取檔名
fileName = mFile.getOriginalFilename();
      if(fileName.lastIndexOf(".")<0 || fileName.lastIndexOf(".")==fileName.length()-1){
         map.put("success", false);
         map.put("msg", "圖片僅支援小於3M的jpg、 png.格式");
         result.add(map);
         continue;
      }
      if(!Pattern.matches("^"+NEW_LIMIT_TYPE+"$", fileName.substring(fileName.lastIndexOf(".")+1))){
         map.put("success", false);
         map.put("msg", "檔案上傳格式不對，只支援jpg、 png格式");
         result.add(map);
         continue;
      }

      String storeName = rename(fileName);

      String noZipName = uploadDir + storeName;



      String zipName = zipName(noZipName);
      logger.info("圖片zipName:"+zipName);
      File uploadFile = new File(uploadDir + storeName);
      FileCopyUtils.copy(mFile.getBytes(), uploadFile);

      // 固定引數值對
map.put(FileOperateUtil.REALNAME, fileName);
      map.put(FileOperateUtil.STORENAME, storeName);
      map.put(FileOperateUtil.SIZE, new File(zipName).length());
      map.put(FileOperateUtil.SUFFIX, "zip");
      map.put(FileOperateUtil.CONTENTTYPE, "application/octet-stream");
      map.put(FileOperateUtil.CREATETIME, new Date());
      map.put("url", relativePath + storeName);
      logger.info("圖片url:"+relativePath + storeName);
      fileName = map.get(FileOperateUtil.STORENAME) + "";
      /**開始：加水印**/
FileInputStream in=new FileInputStream(uploadDir + "/" + fileName);
       Image src=ImageIO.read(in);
       int w=src.getWidth(null);
       int h=src.getHeight(null);
       float alpha = 0.3f; // 透明度
BufferedImage img=new BufferedImage(w,h,BufferedImage.TYPE_INT_RGB);//構建畫板
Graphics2D g=img.createGraphics();//得到畫筆
g.drawImage(src,0,0,w,h,null);//把源圖片寫入畫板
Font fsib30 = new Font("微軟雅黑", Font.BOLD + Font.ITALIC, img.getWidth()/16);
       g.setFont(fsib30);
       g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP,alpha));
       g.setColor(Color.black);
       g.setBackground(Color.white);
       g.rotate(Math.toRadians(-15),
               (double) img.getWidth() / 2, (double) img
               .getHeight() / 2);
       g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                 RenderingHints.VALUE_ANTIALIAS_ON);
       String pressText = "僅供XXX認證使用";
       g.drawString(pressText, (w - (getLength(pressText) * img.getWidth()/16))
                 / 2 + 10, (h - img.getWidth()/16) / 2 + 10);
       g.dispose();//生成圖片
OutputStream out = new FileOutputStream(uploadDir + "/" + fileName);
       JPEGImageEncoder en = JPEGCodec.createJPEGEncoder(out);
       en.encode(img);
       /**結束：加水印**/
      // 自定義引數值對
for (String param : params) {
         map.put(param, values.get(param)[i]);
      }
      result.add(map);
   }
   return result;
}

/**
    * 獲取字元長度，一個漢字作為 1 個字元, 一個英文字母作為 0.5 個字元
* @param text
* @return 字元長度，如：text="中國",返回 2；text="test",返回 2；text="中國ABC",返回 4.
    */
public static int getLength(String text) {
       int textLength = text.length();
       int length = textLength;
       for (int i = 0; i < textLength; i++) {
           if (String.valueOf(text.charAt(i)).getBytes().length > 1) {
               length++;
           }
       }
       return (length % 2 == 0) ? length / 2 : length / 2 + 1;
   }