GridFS操作类

GridFSHandle

 public class GridFSHandle : IDFSHandle
    {
        private readonly MongoDatabase _db;
        private readonly MongoServer _server;
        private readonly string _dbName;
        private readonly MongoGridFS _gridFs;
        private readonly string _connectionString;

        public GridFSHandle()
        {
            _connectionString = System.Configuration.ConfigurationManager.ConnectionStrings["MongoConnectionString"].ToString();
            _dbName = System.Configuration.ConfigurationManager.AppSettings["MongoDBName"];
            _server = MongoServer.Create(_connectionString);
            _db = _server.GetDatabase(_dbName);
            _gridFs = _db.GridFS;
        }
        public GridFSHandle(string connectionString,string dbName)
        {
            _connectionString = connectionString;
            _dbName = dbName;
        }

        public string AddFile(Stream fileStream, string fileName)
        {
            MongoGridFSFileInfo fileInfo = _gridFs.Upload(fileStream, fileName);
            return fileInfo.Id.ToString();
        }

        public bool DeleteFile()
        {
            throw new NotImplementedException();
        }

        public string IsExist(string tag)
        {
            string id = "";
            var files = _gridFs.Find(Query.EQ("md5", BsonValue.Create(tag)));
            if(files.Count() > 0)
            {
                id=files.FirstOrDefault().Id.ToString();
            }
            return id;
        }

        public Stream GetFile(string fileId)
        {
            ObjectId id = ObjectId.Parse(fileId);
            var file = _gridFs.FindOneById(id);
            return file != null ? file.OpenRead() : null;
        }