上一篇介绍了VirtualPathProvider中虚拟文件的实现，参考：ASP.NET VirtualPathProvider (上)。
文件系统中，只有文件是不完整的，还要有目录。本篇介绍VirtualPathProvider中的虚拟目录实现。

实现代码：

using System.Collections;
using System.IO;
using System.Text;
using System.Text.RegularExpressions;
using System.Web;
using System.Web.Caching;
using System.Web.Hosting; namespace Xianfen.Net.MyVirtualPathProvider_Directory
{
    public class MyVirtualPathProvider : VirtualPathProvider
    {
        public static void AppInitialize()
        {
            HostingEnvironment.RegisterVirtualPathProvider(new MyVirtualPathProvider());
        } bool IsVirtualFile(string vPath)
        {
            return Regex.IsMatch(vPath, @".*vfile\d{1}\.aspx", RegexOptions.IgnoreCase);
        } bool IsVirtualDirectory(string vPath)
        {
            string relativePath = VirtualPathUtility.ToAppRelative(vPath); return Regex.IsMatch(relativePath, @"~/vdir\d{1}/.*", RegexOptions.IgnoreCase);
        } public override bool FileExists(string virtualPath)
        {
            if (IsVirtualFile(virtualPath))
            {
                return true;
            }
            else
            {
                return Previous.FileExists(virtualPath);
            }
        } public override CacheDependency GetCacheDependency(string virtualPath, IEnumerable virtualPathDependencies, System.DateTime utcStart)
        {
            if (IsVirtualFile(virtualPath))
            {
                return null;
            }
            else
            {
                return base.GetCacheDependency(virtualPath, virtualPathDependencies, utcStart);
            }
        } public override bool DirectoryExists(string virtualDir)
        {
            if (IsVirtualDirectory(virtualDir))
            {
                return true;
            }
            else
            {
                return base.DirectoryExists(virtualDir);
            }
        } public override VirtualDirectory GetDirectory(string virtualDir)
        {
            if (IsVirtualDirectory(virtualDir))
            {
                return new MyVirtualDirectory(virtualDir);
            }
            else
            {
                return Previous.GetDirectory(virtualDir);
            }
        } public override VirtualFile GetFile(string virtualPath)
        {
            virtualPath = virtualPath.ToLower(); if (IsVirtualFile(virtualPath))
            {
                return new MyVirtualFile(virtualPath);
            }
            else
            {
                return Previous.GetFile(virtualPath);
            }
        }
    }
} namespace Xianfen.Net.MyVirtualPathProvider_Directory
{
    public class MyVirtualFile : VirtualFile
    {
        private string myPath; public MyVirtualFile(string virtualPath)
            : base(virtualPath)
        {
            myPath = virtualPath;
        } public override Stream Open()
        {
            Stream stream = new MemoryStream();
            StreamWriter sw = new StreamWriter(stream);
            StreamReader sr = null; try
            {
                string content = File.ReadAllText(HttpContext.Current.Server.MapPath("~/App_Data/htm.txt"), Encoding.UTF8);
                content = content.Replace("$currentfile$", myPath);

                sw.Write(content);
                sw.Flush();
                stream.Seek(

首先定义了虚拟路径提供者，然后实现了虚拟文件和虚拟目录。值得一提的是，实现虚拟路径时，必须重载VirtualPathProvider的GetCacheDependency方法，可以实现自己的CacheDependency或直接返回null，否则会抛出找不到目录的异常。

运行截图：