code: private PooledConnection getConnectionDirect() throws SQLException {
  		if (null == freePool) {
  			throw new SQLException("PooledDataSource is closed!");
  		}
  
  		final int maxActive = config.getMaxActive();
  		if (maxActive <= 0 || maxActive < this.activeCount) {
  			// 超过最大使用限制
  			throw new SQLException("In used Connection is more than Max Active.");
  		}
  
  		PooledConnection conn = freePool.poll();
  		if (null == conn || conn.open().isClosed()) {
  			conn = this.newConnection();
  		}
  		activeCount++;
  		return conn;
  	}
docs: 直接从连接池中获取连接，如果池中无连接直接抛出异常
  
  @return PooledConnection
  @throws SQLException SQL异常