code: public FileAppender flush() {
  		try(PrintWriter pw = writer.getPrintWriter(true)){
  			for (String str : list) {
  				pw.print(str);
  				if (isNewLineMode) {
  					pw.println();
  				}
  			}
  		}
  		list.clear();
  		return this;
  	}
docs: 刷入到文件
  
  @return this