C#使用GrdiFS实现在MongoDB中对文件操作

public class MongoFactory
    {
        // 读取连接字符串 “mongodb://127.0.0.1:27017”
        private static string strCon = ConfigurationManager.ConnectionStrings["MongoDBConnStr"].ConnectionString;
        private static IMongoDatabase mongoContext;

        static MongoFactory()
        {
            GetMongoContext();
        }

        public static void GetMongoContext()
        {
            var client = new MongoClient(strCon);
            if (client != null)
            {
                //通过数据库名获得上下文 名称可以配置到配置文件里
                mongoContext = client.GetDatabase("TestDB");
            }
        }

        /// <summary>
        /// 上传文件（流）
        /// </summary>
        /// <param name="bucketName">相当于文件夹名</param>
        /// <param name="fileName">文件名</param>
        /// <param name="fs">文件流</param>
        /// <returns></returns>
        public static ObjectId UploadFile(string bucketName, string fileName, Stream fs)
        {
            GridFSBucketOptions options = new GridFSBucketOptions();
            options.BucketName = bucketName;
            var bucket = new GridFSBucket(mongoContext, options);
            var oid = bucket.UploadFromStream(fileName, fs);
            return oid;
        }

        /// <summary>
        /// 获得文件字节数组
        /// </summary>
        /// <param name="bucketName"></param>
        /// <param name="fileId"></param>
        /// <returns></returns>
        public static Byte[] GetFileBytes(string bucketName, string fileId)
        {
            GridFSBucketOptions options = new GridFSBucketOptions();
            options.BucketName = bucketName;
            var bucket = new GridFSBucket(mongoContext, options);
            return bucket.DownloadAsBytes(new ObjectId(fileId));
        }

        /// <summary>
        /// 获得文件流
        /// </summary>
        /// <param name="bucketName"></param>
        /// <param name="fileId"></param>
        /// <returns></returns>
        public static Stream GetFileStream(string bucketName, string fileId)
        {
            MemoryStream stream = new MemoryStream();
            GridFSBucketOptions options = new GridFSBucketOptions();
            options.BucketName = bucketName;
            var bucket = new GridFSBucket(mongoContext, options);
            bucket.DownloadToStream(new ObjectId(fileId), stream);
            return stream;
        }
    }