C#后端生成随机验证码图片(base64格式)，通过接口供前端直接使用

  #region 验证码api
        [HttpGet]
        [System.Web.Http.Route("api/Login/Generate")]
        public async  Task <IHttpActionResult> Generate()
        {
            verifcode = GenerateVerificationCode();
            Bitmap bitmap = GenerateImage(verifcode);
            MemoryStream memoryStream = new MemoryStream();
            bitmap.Save(memoryStream, System.Drawing.Imaging.ImageFormat.Png);
            byte[] imageBytes = memoryStream.ToArray();
            return Json(new { ret = 200, success = true, image = imageBytes,message="aa",data=verifcode });
        }
        private string GenerateVerificationCode()
        {
            // 生成随机验证码，可以根据您的需求自定义生成规则  
            Random random = new Random();
            string chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";//验证码随机出现的值 可自己设定
            int length = 6; // 验证码长度，可以根据您的需求进行调整  
            StringBuilder sb = new StringBuilder();
            for