/// <summary>
/// 下载到某个文件夹，仅提供 Windows 下使用，也仅在 Windows 下经过测试
/// </summary>
/// <param name="url"></param>
/// <param name="downloadFolder"></param>
/// <param name="tempFolder">如不传，将使用 <paramref name="downloadFolder"/>作为下载存放的临时文件夹</param>
/// <param name="logger">下载时的内部日志，默认将使用 Debug 输出</param>
/// <param name="progress">下载进度</param>
/// <param name="sharedArrayPool">共享缓存数组池，默认使用 ArrayPool 池</param>
/// <param name="bufferLength">缓存的数组长度，默认是 65535 的长度</param>
/// <param name="stepTimeOut">每一步 每一分段下载超时时间 默认 10 秒</param>
/// <returns></returns>
public static async Task <FileInfo> DownloadFileToFolderAsync(string url, DirectoryInfo downloadFolder,
DirectoryInfo?tempFolder = null, ILogger <SegmentFileDownloader>?logger = null,
IProgress <DownloadProgress>?progress = null, ISharedArrayPool?sharedArrayPool = null,
int bufferLength = ushort.MaxValue, TimeSpan?stepTimeOut = null)
{
#if !NETFRAMEWORK
// 也许会在非 Windows 下系统使用
if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
{
throw new PlatformNotSupportedException($"当前方法仅供 Windows 系统使用");
}
#endif
downloadFolder.Create();
tempFolder ??= downloadFolder;
tempFolder.Create();
// 创建临时文件
var fileName = FileNameHelper.GuessFileNameFromUrl(url, fallbackName: Path.GetRandomFileName());
var downloadFile = new FileInfo(Path.Combine(tempFolder.FullName, fileName));
var segmentFileDownloader = new InnerSegmentFileDownloader(url, downloadFile, logger, progress, sharedArrayPool, bufferLength, stepTimeOut);
await segmentFileDownloader.DownloadFileAsync();
// 下载完成了之后，尝试移动文件夹
// 优先使用服务器返回的文件名
var finallyFileName = segmentFileDownloader.ServerSuggestionFileName;
if (string.IsNullOrEmpty(finallyFileName))
{
finallyFileName = fileName;
}
var finallyFile = new FileInfo(Path.Combine(downloadFolder.FullName, finallyFileName));
if (finallyFile.FullName.Equals(downloadFile.FullName, StringComparison.OrdinalIgnoreCase))
{
// 这里在 Windows 下可以忽略文件大小写等，但是在 Linux 下就不可以
// 好在此方法当前仅给 Windows 使用
return(finallyFile);
}
if (finallyFile.Exists)
{
// 重新加个名字，理论上这个名字不会重叠
finallyFile = new FileInfo(Path.Combine(finallyFile.Directory.FullName,
Path.GetFileNameWithoutExtension(finallyFile.FullName) + Path.GetRandomFileName() +
finallyFile.Extension));
}
if (Path.GetPathRoot(finallyFile.FullName) == Path.GetPathRoot(downloadFile.FullName))
{
// 相同的驱动器，移动就可以了
// 在非 Windows 下有驱动器么？
downloadFile.MoveTo(finallyFile.FullName);
}
else
{
// 谁这么无聊，用的下载文件和最终文件还不相同
// 那就先复制一下再删除原来的文件
downloadFile.CopyTo(finallyFile.FullName);
downloadFile.Delete();
}
return(finallyFile);
}