C#檔案幫助類FoderHelper實現程式碼如下：

using System;
using System.Data;
using System.Configuration;
using System.Linq;
using System.Web;
using System.IO;
using System.Collections;
using System.Collections.Generic;
using System.Security.AccessControl;
using System.Security.Permissions;
namespace Bll
{
    public class FolderHelper
    {
        //判斷資料夾是否存在
        public static bool checkFolderExits(string path)
        {
            DirectoryInfo dir = new DirectoryInfo(path);
            if (dir.Exists)//資料夾存在
            {   
                return true;
            }
            else
            {
               //dir.Create();//不存在就建立一個
                return false;
            }
        }
        //建立一個資料夾，存在就建立失敗
        public static bool CreateNewFolder(string path)
        {
            DirectoryInfo dir = new DirectoryInfo(path);
 
            if (!dir.Exists)
            {
                dir.Create();
                return true;
            }
            else
                return false;
        }
        /// <summary>
        /// 在指定目錄下建立指定名稱資料夾
        /// </summary>
        /// <param name="ParentsPath"></param>
        /// <param name="NewFolderName"></param>
        /// <returns></returns>
        public static bool CreateNewFolder(string ParentsPath, string NewFolderName)
        {
            string CreatePath = ParentsPath + @"\" + NewFolderName;
            DirectoryInfo dir = new DirectoryInfo(CreatePath);
 
            if (!dir.Exists)
            {
                dir.Create();
                return true;
            }
            else
                return false;
        }
        /// <summary>
        /// 返回目錄下的所有檔名
        /// </summary>
        /// <param name="path"></param>
        /// <returns></returns>
        public static ArrayList getAllFiles(string path)
        {
            DirectoryInfo dir = new DirectoryInfo(path);
            if (dir.Exists)
            {
                FileInfo[] fileinfo = dir.GetFiles();
                ArrayList list = new ArrayList();
                foreach (FileInfo f in fileinfo)
                {
                    list.Add(f.Name);
                }
                return list;
            }
            else
                return null;
        }
        /// <summary>
        /// 計算資料夾的大小
        /// </summary>
        /// <param name="d"></param>
        /// <returns></returns>
        public static long DirSize(DirectoryInfo d)
        {
            long Size = 0;
            // Add file sizes.
            FileInfo[] fis = d.GetFiles();//獲得目錄檔案列表
            foreach (FileInfo fi in fis)
            {
                Size += fi.Length;
            }
            // Add subdirectory sizes.
            DirectoryInfo[] dis = d.GetDirectories();//獲取目錄子目錄列表
            foreach (DirectoryInfo di in dis)
            {
                Size += DirSize(di);
            }
            return Size;
        }
        /// <summary>
        /// 把資料夾得大小轉換成比較合適的表示單位
        /// </summary>
        /// <param name="size"></param>
        /// <returns></returns>
        public static string ViewSize(long size)
        {
            long m=size;
            string viewstr;
            
            if ((m / 1024) > 0)//表示可以轉換成KB
            {
                m = m / 1024;//轉換成KB
                
                if ((m / 1024) > 0)//表示可以轉換成MB
                {
                    m = m / 1024;//轉換成MB了
 
                    if ((m / 1024) > 0)//表示可以轉換成GB
                    {
                        m = m / 1024;//轉換成GB了
                        viewstr = m.ToString() + "GB";
                    }
                    else
                    {
                        viewstr = m.ToString() + "MB";
                    }
                }
                else
                {
                    viewstr = m.ToString() + "KB";
                }
            }
            else
            {
                viewstr = m.ToString() + "byte";
            }
            return viewstr;
        }
        /// <summary>
        /// 刪除指定目錄和內容
        /// </summary>
        /// <param name="dir"></param>
        /// <returns></returns>
        public static bool delDir(string dir)
        {
            bool flag = false;
            DirectoryInfo d = new DirectoryInfo(dir);
            if (d.Exists)//判斷目錄是否存在
            {
                try
                {
                    d.Delete();
                    flag = true;
                }
                catch (Exception e) { flag = false; }
            }
            return flag;
        }
        /// <summary>
        /// 刪除指定檔案
        /// </summary>
        /// <param name="fil"></param>
        /// <returns></returns>
        public static bool delFile(string fil)
        {
            bool flag = false;
            FileInfo d = new FileInfo(fil);
            if (d.Exists)//判斷目錄是否存在
            {
                try
                {
                    d.Delete();
                    flag = true;
                }
                catch (Exception e) { flag = false; }
            }
            return flag;
        }
        public static void Copy(string sourceDirectory, string targetDirectory)
        {
            DirectoryInfo diSource = new DirectoryInfo(sourceDirectory);
            DirectoryInfo diTarget = new DirectoryInfo(targetDirectory);
 
            CopyAll(diSource, diTarget);
        }
        /// <summary>
        /// 複製目錄及子檔案到指定目錄
        /// </summary>
        /// <param name="source"></param>
        /// <param name="target"></param>
        public static void CopyAll(DirectoryInfo source, DirectoryInfo target)
        {
            // Check if the target directory exists, if not, create it.
            if (Directory.Exists(target.FullName) == false)
            {
                Directory.CreateDirectory(target.FullName);
            }
 
            // Copy each file into it's new directory.
            foreach (FileInfo fi in source.GetFiles())
            {
                Console.WriteLine(@"Copying {0}\{1}", target.FullName, fi.Name);
                fi.CopyTo(Path.Combine(target.ToString(), fi.Name), true);
            }
 
            // Copy each subdirectory using recursion.
            foreach (DirectoryInfo diSourceSubDir in source.GetDirectories())
            {
                DirectoryInfo nextTargetSubDir =
                    target.CreateSubdirectory(diSourceSubDir.Name);
                CopyAll(diSourceSubDir, nextTargetSubDir);
            }
        }
 
 
 
        /// <summary>
        /// 迴圈讀取某個目錄下的所有檔案和目錄，查詢有關每一項的一些資訊。返回一個檔案列表
        /// </summary>
        /// <param name="strCurrentDir"></param>
        public static List<fileEntity> FileView(string strCurrentDir)
        {
            List<fileEntity> fileList = new List<fileEntity>();
            DirectoryInfo dir = new DirectoryInfo(strCurrentDir);
 
            foreach (FileSystemInfo fsi in dir.GetFileSystemInfos())//這個迴圈再讀取檔案的資訊
            {
                try
                {
                    //FileSystemInfo 物件可以表示檔案或目錄，從而可以作為 FileInfo 或 DirectoryInfo 物件的基礎。 當分析許多檔案和目錄時，請使用該基類。
                    FileInfo fi;
                    DirectoryInfo di;
                    //建立一個自己寫的實體類的實體
                    fileEntity newfile = new fileEntity();
                    if (fsi is FileInfo)//外層迴圈讀取檔案資訊
                    {
                        //表示當前fsi是檔案
                        fi = (FileInfo)fsi;
                        newfile.fileName = fi.Name;
                        newfile.fileExt = fi.Extension;
                        newfile.fileSize = fi.Length;
                        newfile.FileModify = fi.LastWriteTime;
                        //通過副檔名來選擇檔案顯示圖示
                        switch (newfile.fileExt)
                        {
                            case ".gif":
                                newfile.picName = "gif.gif";
                                break;
                            default:
                                newfile.picName = "other.gif";
                                break;
                        }
                        newfile.picName = "<img src='" + newfile.picName + "' width=25 height=20>";
                    }
                    else
                    {
                        di = (DirectoryInfo)fsi;
                        newfile.fileName = di.Name;
                        newfile.fileSize = DirSize(di);//呼叫計算資料夾大小的方法
                        newfile.FileModify = di.LastWriteTime;
                        newfile.picName = "<img src='directory.gif' width=25 height=20>";
                    }
                    fileList.Add(newfile);
                }
                catch (Exception e) { }
            }
            return fileList;
 
        }
 
 
        /// <summary>
        /// 顯示目錄和檔案
        /// </summary>
        /// <param name="path"></param>
        public static void All(string path)
        {
            FileInfo fi;//檔案
            DirectoryInfo di;//目錄
            DirectoryInfo dir=null;
            int i = 0; //控制行的顏色
            try
            {
                dir = new DirectoryInfo(path);
            }
            catch (Exception e) { }
            foreach (FileSystemInfo fsi in dir.GetFileSystemInfos())
            {
                try
                {
                    fileEntity newfile = new fileEntity();
                    FolderEntity folder = new FolderEntity();
                    newfile.fileName = "";
                    newfile.picName = "";
                    newfile.fileExt = "";
                    newfile.fileSize = 0;
                    folder.folderName = "";
                    folder.picName = "";
 
                    i += 1;
                    if (fsi is FileInfo)//判斷當前讀取的是不是一個檔案
                    {
                        //表示當前fsi是檔案
                        fi = (FileInfo)fsi;
                        newfile.fileName = fi.Name;
                        newfile.fileExt = fi.Extension;
                        newfile.fileSize = fi.Length;
                        newfile.FileModify = fi.LastWriteTime;
 
                        //將檔案加上可以下載檔案的連結
 
 
                        newfile.fileName = "<a href='........'></a>";
 
 
                        //通過副檔名來選擇檔案顯示圖示
 
                        //Response.Write(Session["DataBasePath"].ToString()+"\\filetype\\"+pfun.getFileExt(FileExt)+".gif");
 
                        if (fsi.Exists)
                        {
                            switch (newfile.fileExt)
                            {
                                case ".gif":
                                    newfile.picName = "gif.gif";
                                    break;
                                default:
                                    newfile.picName = "other.gif";
                                    break;
                            }
                        }
                        else
                        {
                            newfile.picName = "unknown.gif";
                        }
 
 
                        /*
                        switch(FileExt)
                        {
                            case ".gif":
                                FilePic = "gif.gif";
                                break;
                            default:
                                FilePic = "other.gif";
                                break;
                        }
                        */
 
                        newfile.picName = "<img src='filetype/" + newfile.picName + "' width=16 height=16>";
 
                    }
                    else
                    {
                        //當前為目錄
                        di = (DirectoryInfo)fsi;
                        folder.folderName = di.Name;
 
                        //給目錄加上鍊接
 
                        folder.folderName = "<a href='.......'><a>";
                        folder.lastTime = di.LastWriteTime;
                        folder.picName = "<img src='filetype/folder.gif' width=16 height=16>";
 
                    }
                }catch(Exception e){}
            }
 
 
        }
    }
}