随机验证码功能实现

public class Tools
{
    public static string CreateValidateString()
    {
        //准备一组供验证码展示的数据
        string chars = "adbcadjas;dasjflkhaflajpoahr";
        Random random = new(DateTime.Now.Millisecond);
        string validateString = "";
        int length = 4;
        for (int i = 0; i < length; i++)
        {
            validateString += chars[random.Next(chars.Length)];
        }
        return validateString;
    }
    public static Byte[] CreteValidataCodeBuffer(string validateCode)
    {
        //bmp->位图
        //1.创建画布，设置画布的长宽
        using Bitmap bitmap = new(200,60);
        //2.创建画笔，告诉画笔在哪个画布上画画
        Graphics graphics = Graphics.FromImage(bitmap);
        //用白色覆盖画布，并清除画布上所有的内容
        graphics.Clear(Color.White);
        //设置字体的参数(设置字体的名称、大小、粗细以及斜体)
        Font font = new("微软雅黑", 12, FontStyle.Bold | FontStyle.Italic);
        //通过graphics.MeasureString方法计算字符串长度
        var Size = graphics.MeasureString(validateCode, font);
        //通过长度生成新的画布
        //1.98 Convert.ToInt32(1.98) = 1
        //向上取整：天花板函数，向下取整：地板函数
        using Bitmap bitmaptext = new(Convert.ToInt32(Math.Ceiling(Size.Width)), Convert.ToInt32(Math.Ceiling(Size.Height)));
        //将文字写入，生成图片
        Graphics graphicstext = Graphics.FromImage(bitmaptext);
        //把图片缩放到原画布上
        //配置画图参数
        //设置颜色刷范围参数
        RectangleF rf = new(0,0,bitmap.Width,bitmap.Height);
        //设置刷子的颜色(设置为渐变)
        LinearGradientBrush brush = new(rf,Color.Red,Color.DarkBlue,1.2f,true);
        //将字符串绘制到场景中
        graphicstext.DrawString(validateCode, font, brush, 0, 0);
        graphics.DrawImage(bitmaptext, 10, 10, 190, 50);
        //将图片放到缓冲区中
        //创建一个用于保存图片的缓冲器
        MemoryStream memoryStream = new();
        //把图片保存到缓冲区
        bitmap.Save(memoryStream, ImageFormat.Jpeg);
        //图片已经放在缓冲区了，bitmap对象没有用了，释放资源
        bitmap.Dispose();
        return memoryStream.ToArray();
    }
}

public class MemoryHelper
 {
     private static IMemoryCache _memoryCache;
     static MemoryHelper()
     {
         if (_memoryCache == null)
         {
             _memoryCache = new MemoryCache(new MemoryCacheOptions());
         }
     }
     public static void SetMemory(string key,object value,int expireMins)
     {
         _memoryCache.Set(key,value,TimeSpan.FromMinutes(expireMins));
     }
     public static object GetMemory(string key)
     {
         return _memoryCache.Get(key);
     }
 }

 //验证码
    [HttpGet]
    public IActionResult GetValidateCodeImage(string code)
    {
        Console.WriteLine(code);
        var validateCodeString = Tools.CreateValidateString();
        //将验证码记入缓存中
        MemoryHelper.SetMemory(code, validateCodeString,1);
        //接受图片返回的二进制流
        byte[] buffer = Tools.CreteValidataCodeBuffer(validateCodeString);
        return File(buffer, @"image/jpeg");
    }

<img src = "validateCodeRef" alt = "" @click = "changeValidateCode"/>

import{validateCodeRef，changeValidateCode} from ""
const validateCode = "localhost:port/url"
onMounted(() =>{
 validateCodeRef.value = validateCode+"?t="+getGuid(); //获取随机标识符
});

const validateCode = "localhost:port/url"
export const validateCodeRef = ref();
export const changeValidateCode = () =>{
   validateCodeRef.value = validateCode+"?t="+getGuid();
};