code: private static void mergeFiles(File file, File destinationFile, String filter) throws IOException {
          String content = readFile(file);
          if (Checker.isNotEmpty(filter)) {
              content = content.replaceAll(filter, ValueConsts.EMPTY_STRING);
          }
          saveFile(destinationFile, content, ValueConsts.TRUE);
      }
docs: 合并文件
  
  @param file 待读取文件
  @param destinationFile 目标文件
  @param filter 过滤规则
  
  @throws IOException 异常