serviceimpl save方法返回的boolean值是什么

本题需要使用按键和数码管，因此需要先定义引脚。

sbit KEY1 = P3^2;
sbit KEY2 = P3^3;
sbit KEY3 = P3^4;
sbit KEY4 = P3^5;
sbit LED = P0;

然后定义一个字符数组，存储要显示的字符。

unsigned char letter[4][8] = {
    {0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00}, //空字符
    {0x3F,0x48,0x48,0x48,0x3F,0x00,0x00,0x00}, //字母A
    {0x3F,0x21,0x21,0x21,0x1E,0x00,0x00,0x00}, //字母B
    {0x1E,0x21,0x21,0x21,0x12,0x00,0x00,0x00}, //字母C
    {0x3F,0x21,0x21,0x21,0x1E,0x00,0x00,0x00}, //字母D
};

接着是数码管显示函数，根据动态显示的原理，每个数码管只能显示一个字符，需要控制显示的时间和显示的位置。

void display(unsigned char *p) //p为要显示的字符指针
{
    unsigned char i, j;
    for(i=0; i<8; i++) //8列循环
    {
        for(j=0; j<4; j++) //4行循环
        {
            LED = 0xFF; //关闭所有数码管
            P2 = 0x01<<j; //选择要显示的数码管
            P1 = ~*(p+i*4+j); //显示对应的字符
            delay(1); //延时
        }
    }
}

最后是主函数，需要轮询按键状态，根据按键状态选择要显示的字符。

void main()
{
    unsigned char key;
    while(1)
    {
        if(KEY1==0) //按键1按下
            key = 1;
        else if(KEY2==0) //按键2按下
            key = 2;
        else if(KEY3==0) //按键3按下
            key = 3;
        else if(KEY4==0) //按键4按下
            key = 4;
        else
            continue;
        display(&letter[key][0]); //显示对应的字符
    }
}

完整代码如下：

#include <reg52.h>

sbit KEY1 = P3^2;
sbit KEY2 = P3^3;
sbit KEY3 = P3^4;
sbit KEY4 = P3^5;
sbit LED = P0;

void delay(unsigned int t)
{
    while(t--);
}

unsigned char letter[4][8] = {
    {0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00}, //空字符
    {0x3F,0x48,0x48,0x48,0x3F,0x00,0x00,0x00}, //字母A
    {0x3F,0x21,0x21,0x21,0x1E,0x00,0x00,0x00}, //字母B
    {0x1E,0x21,0x21,0x21,0x12,0x00,0x00,0x00}, //字母C
    {0x3F,0x21,0x21,0x21,0x1E,0x00,0x00,0x00}, //字母D
};

void display(unsigned char *p)
{
    unsigned char i, j;
    for(i=0; i<8; i++)
    {
        for(j=0; j<4; j++)
        {
            LED = 0xFF;
            P2 = 0x01<<j;
            P1 = ~*(p+i*4+j);
            delay(1);
        }
    }
}

void main()
{
    unsigned char key;
    while(1)
    {
        if(KEY1==0)
            key = 1;
        else if(KEY2==0)
            key = 2;
        else if(KEY3==0)
            key = 3;
        else if(KEY4==0)
            key = 4;
        else
            continue;
        display(&letter[key][0]);
    }
}