code: public static long copy(InputStream in, OutputStream out) throws IORuntimeException {
  		return copy(in, out, DEFAULT_BUFFER_SIZE);
  	}
docs: 拷贝流，使用默认Buffer大小
  
  @param in 输入流
  @param out 输出流
  @return 传输的byte数
  @throws IORuntimeException IO异常