private static void closeConnection(Connection con) {
		if (con != null) {
			try {
				if (!con.isClosed()) { // 关闭没有关闭
					con.close();
				}
			} catch (SQLException ex) {
				LOGGER.debug("关闭JDBC Connection失败", ex);
			} catch (Throwable ex) {
				// We don't trust the JDBC driver: It might throw
				// RuntimeException or Error.
				LOGGER.debug("关闭JDBC Connection时发生未知异常", ex);
			}
		}
	}