如何在C#中复制目录的全部内容？

using System;
using System.IO;
namespace DemoApplication {
   class Program {
      public static void Main() {
         string sourceDirectory = @"d:\DemoSourceDirectory";
         string targetDirectory = @"d:\DemoTargetDirectory";
         DirectoryInfo sourceDircetory = new DirectoryInfo(sourceDirectory);
         DirectoryInfo targetDircetory = new DirectoryInfo(targetDirectory);
         CopyAll(sourceDircetory, targetDircetory);
         Console.ReadLine();
      }
      public static void CopyAll(DirectoryInfo source, DirectoryInfo target) {
         Directory.CreateDirectory(target.FullName);
         foreach (FileInfo fi in source.GetFiles()) {
            Console.WriteLine(@"Copying {0}\{1}", target.FullName, fi.Name);
            fi.CopyTo(Path.Combine(target.FullName, fi.Name), true);
         }
         foreach (DirectoryInfo diSourceSubDir in source.GetDirectories()) {
            DirectoryInfo nextTargetSubDir =
            target.CreateSubdirectory(diSourceSubDir.Name);
            CopyAll(diSourceSubDir, nextTargetSubDir);
         }
      }
   }
}