STM32的USART应用问题（不定时添加）

void USART1_IRQHandler(void)                    //串口1中断服务程序
{
    u8 Res;
    u8 DataCount= 0;
    if(USART_GetITStatus(USART1, USART_IT_PE) != RESET)
    {
        USART_ReceiveData(USART1);
        USART_ClearFlag(USART1,USART_FLAG_RXNE);
    }
    if(USART_GetITStatus(USART1, USART_IT_ORE) != RESET)
    {
        USART_ReceiveData(USART1);
        USART_ClearFlag(USART1,USART_IT_ORE);
    }
    if(USART_GetITStatus(USART1, USART_IT_FE) != RESET)
    {
        USART_ReceiveData(USART1);
        USART_ClearFlag(USART1,USART_IT_FE);
    }
    if(USART_GetITStatus(USART1, USART_IT_RXNE) != RESET)  
    {
        Res = USART_ReceiveData(USART1);    //读取接收到的数据
    } 
}