code: public static String read(InputStream in, String charsetName) throws IORuntimeException {
  		FastByteArrayOutputStream out = read(in);
  		return StrUtil.isBlank(charsetName) ? out.toString() : out.toString(charsetName);
  	}
docs: 从流中读取内容
  
  @param in 输入流
  @param charsetName 字符集
  @return 内容
  @throws IORuntimeException IO异常