public IActionResult UploadByFile()
        {
            // 生成(上传)凭证时需要使用此Mac
            // 这个示例单独使用了一个Settings类,其中包含AccessKey和SecretKey
            // 实际应用中,请自行设置您的AccessKey和SecretKey
            Mac mac = new Mac(accessKey, secretKey);
            //你的OSS的名称
            string bucket = this.bucket;

            string saveKey   = Guid.NewGuid() + ".png";
            string localFile = "C:\\Users\\86551\\Desktop\\test.png";
            // 上传策略,参见
            // https://developer.qiniu.com/kodo/manual/put-policy
            PutPolicy putPolicy = new PutPolicy();

            // 如果需要设置为"覆盖"上传(如果云端已有同名文件则覆盖),请使用 SCOPE = "BUCKET:KEY"
            // putPolicy.Scope = bucket + ":" + saveKey;
            putPolicy.Scope = bucket;
            // 上传策略有效期(对应于生成的凭证的有效期)
            putPolicy.SetExpires(3600);
            // 上传到云端多少天后自动删除该文件,如果不设置(即保持默认默认)则不删除
            //putPolicy.DeleteAfterDays = 1;
            // 生成上传凭证,参见
            // https://developer.qiniu.com/kodo/manual/upload-token
            string                  jstr     = putPolicy.ToJsonString();
            string                  token    = Auth.CreateUploadToken(mac, jstr);
            UploadManager           um       = new UploadManager();
            HttpResult              result   = um.UploadFile(localFile, saveKey, token);
            QiNiuFileUploadResponse response = JsonConvert.DeserializeObject <QiNiuFileUploadResponse>(result.Text);

            return(Json(result));
        }
        private string UploadStream(Stream fileStream)
        {
            Mac       mac       = new Mac(accessKey, secretKey);
            string    bucket    = this.bucket;
            string    saveKey   = Guid.NewGuid() + ".png";
            PutPolicy putPolicy = new PutPolicy();

            putPolicy.Scope = bucket;
            putPolicy.SetExpires(3600);
            string        jstr   = putPolicy.ToJsonString();
            string        token  = Auth.CreateUploadToken(mac, jstr);
            UploadManager um     = new UploadManager();
            HttpResult    result = um.UploadStream(fileStream, saveKey, token);

            fileStream.Close();
            QiNiuFileUploadResponse response = JsonConvert.DeserializeObject <QiNiuFileUploadResponse>(result.Text);

            return(response.key);
        }