FileServerOptions options = new FileServerOptions{    FileProvider = PhysicalFileProvider("自定义根目录"),    EnableDefaultFiles = true,    EnableDirectoryBrowsing = false,};app.UseFileServer(options);

builder.Services.AddHttpContextAccessor();builder.Services.AddSingleton<DynamicFileProvider>();IHttpContextAccessor httpContextAccessor = app.Services.GetService<IHttpContextAccessor >()DynamicFileProvider dfp = app.Services.GetService<DynamicFileProvider>();//设置一个默认目录dfp.SetDefault(Path.Combine(app.Environment.ContentRootPath, "web"));FileServerOptions options = new FileServerOptions{    FileProvider = dfp,    EnableDefaultFiles = true,    EnableDirectoryBrowsing = false,};app.UseFileServer(options);

public class DynamicFileProvider : IFileProvider{    private PhysicalFileProvider defaultFileProvider;    private readonly IHttpContextAccessor httpContextAccessor;    public DynamicFileProvider(IHttpContextAccessor httpContextAccessor)    {        this.httpContextAccessor = httpContextAccessor;        SearchTask();    }    public void SetDefault(string defaultPath)    {        if (Directory.Exists(defaultPath) == false)        {            Directory.CreateDirectory(defaultPath);        }        this.defaultFileProvider = new PhysicalFileProvider(defaultPath);    }    public IFileInfo GetFileInfo(string subpath)    {        IFileProvider fileProvider = GetFileProvider();        return fileProvider.GetFileInfo(subpath);    }    public IDirectoryContents GetDirectoryContents(string subpath)    {        IFileProvider fileProvider = GetFileProvider();        return fileProvider.GetDirectoryContents(subpath);    }    public IChangeToken Watch(string filter)    {        IFileProvider fileProvider = GetFileProvider();        return fileProvider.Watch(filter);    }    private IFileProvider GetFileProvider()    {        HttpContext httpContext = httpContextAccessor.HttpContext;        string host = httpContext?.Request.Host.Host ?? string.Empty;        string path = httpContext?.Request.Path ?? string.Empty;        FileProviderInfo provider;        if (IPAddress.TryParse(host, out _) == false)        {            //根据 host.Split('.')[0] 获取        }        if (string.IsNullOrWhiteSpace(path) == false)         {            //根据 path.Split('/')[1] 获取        }        //都没有就默认的        return defaultFileProvider;    }}