MD5加密之提取文件的MD5特征码

 public static String encodeFile(String path) {

         try {
             MessageDigest digester = MessageDigest.getInstance("MD5");

             FileInputStream in = new FileInputStream(path);

             byte[] bytes = new byte[];
             int byteCount;
             while ((byteCount = in.read(bytes)) > ) {
                 digester.update(bytes, , byteCount);
             }
             byte[] digest = digester.digest();

             //用StringBuffer拼接字节数组
             StringBuffer sb = new StringBuffer();
             for (byte b : digest) {
                 String str = Integer.toHexString(b & 0xff);
                 if(str.length() == ){
                     str = "" + str;
                 }
                 sb.append(str);
             }
             in.close();

             return sb.toString();

         } catch (Exception e) {
             e.printStackTrace();
         }
         return null;
     }