/// <summary> 获取下好的文件 返回null则需要等待 </summary>
        public string GetWaitCurrent(string file, Action <bool, int, int> action)
        {
            //  Message:如果没下载完,则等待15s数据都下载完为止
            flag = false;

            var result = this._fileCollection.Find(l => l.FilePath == file);

            int last = this._fileCollection.FindIndex(l => l.FilePath == _current.FilePath);

            int now = this._fileCollection.FindIndex(l => l.FilePath == file);

            _current = result;

            //  Message:如果时间相差较多,重新分配下载区间
            if (now - last > 5 * 15)
            {
                this.RefreshPosition(_current.FilePath);
            }

            if (last - now > 0)
            {
                this.RefreshPosition(_current.FilePath);
            }

            if (result.IsLoaded == 2)
            {
                return(result.LocalPath);
            }
            else
            {
                Thread.Sleep(1000);

                flag = true;

                var waitCache = _fileCollection.Skip(now).Take(this.Capacity).ToList();

                while (!waitCache.TrueForAll(l => l.IsLoaded == 2))
                {
                    if (!flag)
                    {
                        Debug.WriteLine("取消等待");
                        return(null);
                    }
                    Thread.Sleep(500);

                    action(false, waitCache.FindAll(l => l.IsLoaded == 2).Count, waitCache.Count);
                }

                action(true, waitCache.FindAll(l => l.IsLoaded == 2).Count, waitCache.Count);

                return(result.LocalPath);
            }
        }
        public ImageCacheEngine(List <string> filePath, string localFolder, string startFile, string user, string password, string ip = "")
        {
            this.ID = Guid.NewGuid().ToString();

            this.LocalFolder = Path.Combine(localFolder, this.ID);

            if (!Directory.Exists(this.LocalFolder))
            {
                Directory.CreateDirectory(this.LocalFolder);
            }

            foreach (var item in filePath)
            {
                string localPath = Path.Combine(localFolder, this.ID, Path.GetFileName(item));

                ImageCacheEntity entity = new ImageCacheEntity(item, localPath, user, password, ip);

                _fileCollection.Add(entity);
            }

            _current = _fileCollection.Find(l => l.FilePath == startFile);;
        }