MINISTM32串口中断方式无法接受，可以发送，为啥呢？

#include "stm32f10x_lib.h"
#include<stdio.h>
#ifdef __GNUC__
/* With GCC/RAISONANCE, small printf (option LD Linker->Libraries->Small printf
     set to 'Yes') calls __io_putchar() */
#define PUTCHAR_PROTOTYPE int __io_putchar(int ch)
#else
#define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f)
#endif
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
ErrorStatus HSEStartUpStatus;
void RCC_Configuration(void);
void NVIC_Configuration(void);
void USART_Config(void);
//void USART1_Puts(char * str);//输出字符串
void USART1_Putchar(u8 ch);//输出一个字符
//unsigned char USART1_ReceiveChar(void);//接收一个字符
//char rbuff[100];
int main(void)
{
  RCC_Configuration();     
  NVIC_Configuration();
  USART_Config();
  USART1_Putchar(0x11);
  while(1)
  {
  }
}
/*******************************************************************************
* Function Name  : RCC_Configuration
* Description    : Configures the different system clocks.
* Input          : None
* Output         : None
* Return         : None
*******************************************************************************/
void RCC_Configuration(void)
{
// ErrorStatus HSEStartUpStatus;
  /* RCC system reset(for debug purpose) */
  RCC_DeInit();
  /* Enable HSE */
  RCC_HSEConfig(RCC_HSE_ON);
  /* Wait till HSE is ready */
  HSEStartUpStatus = RCC_WaitForHSEStartUp();
  if(HSEStartUpStatus == SUCCESS)
  {
    /* Enable Prefetch Buffer */
    FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);
    /* Flash 2 wait state */
    FLASH_SetLatency(FLASH_Latency_2);
    /* HCLK = SYSCLK */
    RCC_HCLKConfig(RCC_SYSCLK_Div1);
    /* PCLK2 = HCLK */
    RCC_PCLK2Config(RCC_HCLK_Div1); //串口
    /* PCLK1 = HCLK/2 */
    RCC_PCLK1Config(RCC_HCLK_Div2);
    /* PLLCLK = 8MHz * 9 = 72 MHz */
    //RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_9);
         RCC_PLLConfig(RCC_PLLSource_HSI_Div2, RCC_PLLMul_12);         //4M*12 =48M
    /* Enable PLL */
    RCC_PLLCmd(ENABLE);
    /* Wait till PLL is ready */
    while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET)
    {
    }
    /* Select PLL as system clock source */
    RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
    /* Wait till PLL is used as system clock source */
    while(RCC_GetSYSCLKSource() ！= 0x08)
    {
    }
   RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA|RCC_APB2Periph_AFIO, ENABLE);
   RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1,ENABLE);
  }   
}
void USART_Config(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    USART_InitTypeDef USART_InitStructure;
    /* Configure USART1_Tx as alternate function push-pull */
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_Init(GPIOA, &GPIO_InitStructure);
    /* Configure USART1_Rx as input floating */
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    GPIO_Init(GPIOA, &GPIO_InitStructure);
    //USART工作在异步模式下
    USART_InitStructure.USART_BaudRate = 9600;//波特率
    USART_InitStructure.USART_WordLength = USART_WordLength_8b;//数据位数
    USART_InitStructure.USART_StopBits = USART_StopBits_1;//一个停止位
    USART_InitStructure.USART_Parity = USART_Parity_No ;//无奇偶校验位
    USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;//无硬件控制流
    USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;//发送接收均使能
    /* Configure the USARTx */
    USART_Init(USART1, &USART_InitStructure);
        
    USART_ITConfig(USART1,USART_IT_RXNE,ENABLE);   //若接收寄存器满，产生中断
        //printf("ab") ;
    /* Enable the USARTx */
    USART_Cmd(USART1, ENABLE);                //控制寄存器13位置1
   /*解决第一字节无法发送的问题*/
//        USART_ClearFlag(USART1,USART_FLAG_TC); //清标志
}
/*******************************************************************************
* Function Name  : NVIC_Configuration
* Description    : Configures Vector Table base location.
* Input          : None
* Output         : None
* Return         : None
*******************************************************************************/
void NVIC_Configuration(void)
{
  NVIC_InitTypeDef  NVIC_InitStructure;
//#ifdef  VECT_TAB_RAM  
  /* Set the Vector Table base location at 0x20000000 */
//  NVIC_SetVectorTable(NVIC_VectTab_RAM, 0x0);
//#else  /* VECT_TAB_FLASH  */
  /* Set the Vector Table base location at 0x08000000 */
  NVIC_SetVectorTable(NVIC_VectTab_FLASH, 0x0);   
//#endif
  NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);//配置优先级组为第1组（抢占式优先级有1位，副优先级有3位）
  //配置USART中断
  NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQChannel;//中断通道为RTC全局中断
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;//抢占优先级为1
//NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;//副优先级为0
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;//中断通道使能
  NVIC_Init(&NVIC_InitStructure);//初始化NVIC结构体
}
void USART1_Putchar(u8 ch)
{
    USART_SendData(USART1,(u8) ch);
    /* Loop until the end of transmission */
    while(USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET);//等待发送完成
}


void USART1_IRQHandler(void)
{         
  u8 dat;
// if (USART_GetITStatus(USART1,USART_IT_RXNE)！= RESET)//查询是否为中断标志
if(USART_GetFlagStatus(USART1, USART_FLAG_RXNE)！=RESET)
  {
           dat=USART_ReceiveData(USART1);
           USART_ClearITPendingBit(USART1,USART_IT_RXNE);
                if(dat==0x63)
                {dat=0;
                USART1_Putchar(0x77);
                USART1_Putchar(0x97);
                }
                while(USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET){}
   }
}