STM32三个按键触发三个外部中断，设置成一个中断时正常，三个中断都配置，就会不工作。

程序如下：
void exti_init()  
{
        GPIO_InitTypeDef GPIO_InitStructure;
        EXTI_InitTypeDef EXTI_InitStructure;
        NVIC_InitTypeDef NVIC_InitStructure;


        RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO,ENABLE);
        RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOE,ENABLE);

        GPIO_InitStructure.GPIO_Pin=k_left|k_down|k_right;
        GPIO_InitStructure.GPIO_Mode=GPIO_Mode_IPU;
        GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz;
        GPIO_Init(GPIOE,&GPIO_InitStructure);
         
        GPIO_EXTILineConfig(GPIO_PortSourceGPIOE, GPIO_PinSource2);
        NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);                 
        NVIC_InitStructure.NVIC_IRQChannel = EXTI2_IRQn;         //´ò¿ªEXTI2µÄÈ«¾ÖÖжÏ
        NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2; //ÇÀÕ¼ÓÅÏȼ¶Îª0
        NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;                  //ÏìÓ¦ÓÅÏȼ¶Îª0
        NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;                   //ʹÄÜ
        NVIC_Init(&NVIC_InitStructure);


//        GPIO_EXTILineConfig(GPIO_PortSourceGPIOE, GPIO_PinSource3);
//        NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);                 
//        NVIC_InitStructure.NVIC_IRQChannel = EXTI3_IRQn;         //´ò¿ªEXTI2µÄÈ«¾ÖÖжÏ
//        NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2; //ÇÀÕ¼ÓÅÏȼ¶Îª0
//        NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;                  //ÏìÓ¦ÓÅÏȼ¶Îª0
//        NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;                   //ʹÄÜ
//        NVIC_Init(&NVIC_InitStructure);
       
//       

//        GPIO_EXTILineConfig(GPIO_PortSourceGPIOE, GPIO_PinSource4);
//        //NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);                 
//        NVIC_InitStructure.NVIC_IRQChannel = EXTI2_IRQn;         //´ò¿ªEXTI2µÄÈ«¾ÖÖжÏ
//        NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2; //ÇÀÕ¼ÓÅÏȼ¶Îª0
//        NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2;                  //ÏìÓ¦ÓÅÏȼ¶Îª0
//        NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;                   //ʹÄÜ
//        NVIC_Init(&NVIC_InitStructure);
//       
       
        /* ÉèÖÃÍⲿÖжϵÄģʽ */
        EXTI_InitStructure.EXTI_Line=EXTI_Line2|EXTI_Line3|EXTI_Line4;
        EXTI_InitStructure.EXTI_Mode=EXTI_Mode_Interrupt;
        EXTI_InitStructure.EXTI_Trigger=EXTI_Trigger_Falling;
        EXTI_InitStructure.EXTI_LineCmd = ENABLE;
        EXTI_Init(&EXTI_InitStructure);

}