遍历文件系统目录树的深入理解

/// <summary>
    /// 通过递归方式访问目录树
    /// </summary>
    class RecursiveAccessDirectory
    {
        //声明并实例化一个字符串集合
        static System.Collections.Specialized.StringCollection log
            = new System.Collections.Specialized.StringCollection();
        static void Main()
        {
            /*该部门代码循环访问本机所有驱动器上的文件
             *
             *
            //返回计算机逻辑驱动器名称的字符串数组
            //包括光驱及连接计算机的移动驱动器
            string[] drives = System.Environment.GetLogicalDrives();
            foreach (string dr in drives)
            {
                System.IO.DriveInfo di = new System.IO.DriveInfo(dr);
                if (!di.IsReady)
                {
                    Console.WriteLine("驱动器 {0} 不能读出", di.Name);
                    continue;
                }
                System.IO.DirectoryInfo rootDir = di.RootDirectory;
                WalkDirectoryTree(rootDir);
            }
           */
            /*循环访问指定目录下的文件夹
             *
             */
            System.IO.DirectoryInfo rootDir = new System.IO.DirectoryInfo(@"C:\test");
            WalkDirectoryTree(rootDir);
            Console.WriteLine("限制用户访问文件:");
            foreach (string s in log)
            {
                Console.WriteLine(s);
            }
            Console.Read();
        }

      
        static void WalkDirectoryTree(System.IO.DirectoryInfo root)
        {
            System.IO.FileInfo[] files = null;
            System.IO.DirectoryInfo[] subDirs = null;
            try
            {
                //GetFiles方法的参数可以包含通配符。
                //即使目录下没有匹配的文件，返回长度为0不为空的数组对象，
                //所以递归函数可以放在if (files != null)里。
                //下面为查找所有有后缀名的文件。
                files = root.GetFiles("*.*");
            }
            //请求权限超过应用程序提供权限抛出异常
            catch (System.UnauthorizedAccessException e)
            {
                //在访问某个文件夹遭受拒绝时，
                //您可以提升自己的权限，然后再次访问它。
                log.Add(e.Message);
            }
            catch (System.IO.DirectoryNotFoundException e)
            {
                Console.WriteLine(e.Message);
            }

            if (files != null)
            {
                foreach (System.IO.FileInfo fi in files)
                {
                    Console.WriteLine("{0}: {1} {2}", fi.FullName, fi.Length, fi.CreationTime);
                }
                subDirs = root.GetDirectories();
                foreach (System.IO.DirectoryInfo dirInfo in subDirs)
                {
                    WalkDirectoryTree(dirInfo);
                }
            }
        }
    }

/// <summary>
    /// 通过堆栈方式访问目录树
    /// </summary>
    class StackAccessDirectory
    {

        static void Main()
        {
            TraverseTree(@"C:\test");
            Console.Read();
        }

        public static void TraverseTree(string root)
        {
            Stack<string> dirs = new Stack<string>(20);
            if (!System.IO.Directory.Exists(root))
            {
                throw new ArgumentException();
            }
            dirs.Push(root);
            while (dirs.Count > 0)
            {
                string currDir = dirs.Pop();
                string[] subDirs;
                try
                {
                    subDirs = System.IO.Directory.GetDirectories(currDir);
                }
                catch (System.UnauthorizedAccessException e)
                {
                    Console.WriteLine(e.Message);
                    continue;
                }
                catch (System.IO.DirectoryNotFoundException e)
                {
                    Console.WriteLine(e.Message);
                    continue;
                }
                string[] files=null;
                try
                {
                    files=System.IO.Directory.GetFiles(currDir);
                }
                catch(System.UnauthorizedAccessException e)
                {
                    Console.WriteLine(e.Message);
                    continue;
                }
                catch(System.IO.DirectoryNotFoundException e)
                {
                    Console.WriteLine(e.Message);
                    continue;
                }
                foreach (string file in files)
                {
                    try
                    {
                        System.IO.FileInfo fi = new System.IO.FileInfo(file);
                        Console.WriteLine("{0}: {1} {2}", fi.Name, fi.Length, fi.CreationTime);
                    }
                    catch (System.IO.FileNotFoundException e)
                    {
                        Console.WriteLine(e.Message);
                        continue;
                    }
                }
                foreach (string str in subDirs)
                    dirs.Push(str);
            }
        }
    }