code: public static BufferedReader getReader(File file, String charsetName) throws IORuntimeException {
  		return IoUtil.getReader(getInputStream(file), charsetName);
  	}
docs: 获得一个文件读取器
  
  @param file 文件
  @param charsetName 字符集
  @return BufferedReader对象
  @throws IORuntimeException IO异常