/// <summary>
/// 下载图片，不在本地缓存文件，直接返回BitmapImage对象
/// </summary>
/// <param name="p_path">要下载的文件路径</param>
/// <returns></returns>
public static async Task <BitmapImage> GetImage(string p_path)
{
if (string.IsNullOrEmpty(p_path))
{
return(null);
}
// 路径肯定含/
int index = p_path.LastIndexOf('/');
if (index <= 0)
{
return(null);
}
MemoryStream stream = new MemoryStream();
DownloadInfo info = new DownloadInfo
{
Path = p_path,
TgtStream = stream,
};
bool suc = false;
try
{
suc = await GetFile(info, CancellationToken.None);
if (suc)
{
stream.Seek(0, SeekOrigin.Begin);
BitmapImage bmp = new BitmapImage();
#if UWP
var randomStream = new InMemoryRandomAccessStream();
var outputStream = randomStream.GetOutputStreamAt(0);
await RandomAccessStream.CopyAsync(stream.AsInputStream(), outputStream);
await bmp.SetSourceAsync(randomStream);
#else
await bmp.SetSourceAsync(stream);
#endif
return(bmp);
}
}
finally
{
stream.Close();
}
return(null);
}
/// <summary>
/// 下载文件并缓存到本地
/// </summary>
/// <param name="p_path">要下载的文件路径，以原有文件名缓存到本地</param>
/// <returns>false 下载失败，缓存文件已删除</returns>
public static async Task <bool> GetAndCacheFile(string p_path)
{
if (string.IsNullOrEmpty(p_path))
{
return(false);
}
// 路径肯定含/
int index = p_path.LastIndexOf('/');
if (index <= 0)
{
return(false);
}
string path = Path.Combine(Kit.CachePath, p_path.Substring(index + 1));
FileStream stream = File.Create(path);
DownloadInfo info = new DownloadInfo
{
Path = p_path,
TgtStream = stream,
};
bool suc = false;
try
{
suc = await GetFile(info, CancellationToken.None);
}
finally
{
stream.Close();
}
if (!suc)
{
// 未成功，删除缓存文件，避免打开时出错
try
{
// mono中 FileInfo 的 Exists 状态不同步！
if (System.IO.File.Exists(path))
{
System.IO.File.Delete(path);
}
}
catch { }
}
return(suc);
}
/// <summary>
/// 执行下载
/// </summary>
/// <param name="p_priorThumbnail">是否优先下载缩略图</param>
/// <param name="p_prompt">是否提示下载失败信息</param>
/// <returns></returns>
internal async Task <bool> Download(bool p_priorThumbnail = false, bool p_prompt = true)
{
if (State != FileItemState.None || string.IsNullOrEmpty(ID))
{
if (p_prompt)
{
Kit.Warn("当前状态不可下载！");
}
return(false);
}
bool downloadThumb = false;
if (p_priorThumbnail)
{
// 优先下载缩略图时，先判断是否存在
downloadThumb = await AtFile.Exists(ID + ThumbPostfix);
// 缩略图不存在时，若为视频文件不下载
if (!downloadThumb && FileType != FileItemType.Image)
{
return(false);
}
}
string path = Path.Combine(Kit.CachePath, downloadThumb ? GetThumbName() : GetFileName());
FileStream stream = null;
try
{
if (System.IO.File.Exists(path))
{
System.IO.File.Delete(path);
}
stream = System.IO.File.Create(path);
}
catch (Exception ex)
{
if (p_prompt)
{
Kit.Warn("创建文件出错！");
}
Log.Error(ex, "下载前创建文件出错！");
return(false);
}
State = FileItemState.Downloading;
DownloadInfo info = new DownloadInfo
{
Path = downloadThumb ? ID + ThumbPostfix : ID,
TgtStream = stream,
Progress = OnDownloadProgress,
};
bool suc = false;
_ctsDownload?.Dispose();
_ctsDownload = new CancellationTokenSource();
try
{
suc = await Downloader.GetFile(info, _ctsDownload.Token);
}
catch (Exception ex)
{
Log.Error(ex, "下载出错");
}
finally
{
_ctsDownload?.Dispose();
info.TgtStream.Close();
State = FileItemState.None;
}
if (!suc)
{
if (p_prompt)
{
Kit.Warn(info.Error);
}
// 未成功，删除缓存文件，避免打开时出错
try
{
// mono中 FileInfo 的 Exists 状态不同步！
if (System.IO.File.Exists(path))
{
System.IO.File.Delete(path);
}
}
catch { }
}
else
{
VisualStateManager.GoToState(this, "Cached", true);
}
return(suc);
}
/// <summary>
/// 下载文件，将下载内容写入目标流
/// </summary>
/// <param name="p_info">下载描述</param>
/// <param name="p_token"></param>
/// <returns>是否成功</returns>
public static async Task <bool> GetFile(DownloadInfo p_info, CancellationToken p_token)
{
if (p_info == null || string.IsNullOrEmpty(p_info.Path) || p_info.TgtStream == null)
{
return(false);
}
HttpResponseMessage response = null;
using (await _locker.LockAsync())
using (var request = CreateRequestMessage(p_info.Path))
{
try
{
response = await _client.SendAsync(request, HttpCompletionOption.ResponseHeadersRead, p_token).ConfigureAwait(false);
}
catch (TaskCanceledException)
{
p_info.Error = "已取消下载！";
return(false);
}
catch (Exception ex)
{
p_info.Error = "😢下载过程中出错！" + ex.Message;
return(false);
}
}
// 下载失败
if (response.Headers.TryGetValues("error", out var vals))
{
p_info.Error = WebUtility.UrlDecode(vals.First());
return(false);
}
// 文件长度
long total;
if (!response.Content.Headers.TryGetValues("Content-Length", out var lgh) || !long.TryParse(lgh.First(), out total))
{
p_info.Error = "😢待下载的文件长度未知，下载失败！";
return(false);
}
try
{
using (var inputStream = await response.Content.ReadAsStreamAsync())
{
int read;
int readTotal = 0;
byte[] data = new byte[81920];
while ((read = await inputStream.ReadAsync(data, 0, data.Length, p_token).ConfigureAwait(false)) > 0)
{
await p_info.TgtStream.WriteAsync(data, 0, read);
readTotal += read;
p_info.Progress?.Invoke(read, readTotal, total);
}
await p_info.TgtStream.FlushAsync();
}
}
catch (TaskCanceledException)
{
p_info.Error = "已取消下载！";
return(false);
}
catch (Exception ex)
{
p_info.Error = "😢下载过程中出错！" + ex.Message;
return(false);
}
return(true);
}