后端生成验证码

一、前端请求

/**
 * 获取验证码
 */
export async function getCaptcha() {
    // 这是前端的请求，用的是axios
  const res = await request.get('/Commons/getCaptcha');
  if (res.data.code == 200) {
    return res.data.data;
  }
  return Promise.reject(new Error(res.data.message));
}

二、后端实现

请求方法控制器

[HttpGet]
public JObject getCaptcha()
{
    
    JObject json = new JObject();
    string code = "";
    var imageBase64 = GenerateCode(out code); // 生成验证码

    CaptchaObj captchaObj = new CaptchaObj();
    captchaObj.base64 = "data:image/png;base64,"+imageBase64.ToString();
    captchaObj.text = code;

    string result = JsonConvert.SerializeObject(captchaObj);
    var obj = JObject.Parse(result);
    json.Add("code", "200");
    json.Add("data", obj);
    json.Add("message", "操作成功!");

    return json;
}

二、生成验证码

/// <summary>
/// 生成验证码
/// </summary>
/// <param name="codeLen">验证码长度</param>
/// <returns></returns>
private string GenerateCode(out string code,int codeLen = 5)
{
    string letters = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
    code = string.Empty;
    Random random = new Random();
    //生成四位验证码
    for (int i = 0; i < 5; i++)
    {
        code+= letters[random.Next(0, letters.Length)];
    }

    /*这里将code保存下来做比对验证*/

    //生成验证码图片并显示到pictureBox1
    byte[] bytes = GenerateImg(code); // 生成图片字节
    MemoryStream ms = new MemoryStream(bytes);
    return Convert.ToBase64String(bytes);
    //pictureBox1.Image = image;
}

三、生成验证码图片

public byte[] GenerateImg(string code)
{
    Bitmap image = new Bitmap(code.Length * 12, 25);
    Graphics g = Graphics.FromImage(image);
    try
    {
        //清空图片背景色
        g.Clear(Color.White);

        //增加背景干扰线
        Random random = new Random();
        for (int i = 0; i < 30; i++)
        {
            int x1 = random.Next(image.Width);
            int x2 = random.Next(image.Width);
            int y1 = random.Next(image.Height);
            int y2 = random.Next(image.Height);
            //颜色可自定义
            g.DrawLine(new Pen(Color.FromArgb(255, 212, 231)), x1, y1, x2, y2);
            //g.DrawLine(new Pen(Color.FromArgb(120, 150, 210)), x1, y1, x2, y2);
        }

        //定义验证码字体
        Font font = new Font("Arial", 10, (FontStyle.Bold | FontStyle.Italic | FontStyle.Strikeout));
        //定义验证码的刷子，这里采用渐变的方式，颜色可自定义
        LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.FromArgb(67, 93, 230), Color.FromArgb(70, 128, 228), 1.5f, true);

        //增加干扰点
        for (int i = 0; i < 100; i++)
        {
            int x = random.Next(image.Width);
            int y = random.Next(image.Height);
            //颜色可自定义
            image.SetPixel(x, y, Color.FromArgb(random.Next()));
        }

        //将验证码写入图片
        g.DrawString(code, font, brush, 5, 5);


        //图片边框
        g.DrawRectangle(new Pen(Color.FromArgb(93, 142, 228)), 0, 0, image.Width - 1, image.Height - 1);

        //保存图片数据
        MemoryStream stream = new MemoryStream();
        //image.Save("C:/Users/admin/Desktop/省平台/a.jpeg", System.Drawing.Imaging.ImageFormat.Jpeg);
        image.Save(stream, System.Drawing.Imaging.ImageFormat.Jpeg);
        return stream.ToArray();
    }
    finally
    {
        g.Dispose();
        image.Dispose();
    }

}

四、最后效果图