code: public static boolean isFileEqual(File oldFile, File newFile) {
  
          try {
  
              return contentEquals(oldFile, newFile);
  
          } catch (IOException e) {
  
              logger.warn(e.toString());
              return false;
          }
  
      }
docs: http://blog.csdn.net/very365_1208/article/details/8824033
  http://www.avajava.com/tutorials/lessons/whats-a-quick-way
  -to-tell-if-the-contents-of-two-files-are-identical-or-not.html
  
  @param oldFile
  @param newFile
  
  @return