这里有一个简洁而有效的解决方案:

namespace System.IO {
  public static class ExtensionMethods {

    public static void CopyTo(this DirectoryInfo srcPath, string destPath) {
      Directory.CreateDirectory(destPath);
      Parallel.ForEach(srcPath.GetDirectories("*", SearchOption.AllDirectories), 
        srcInfo => Directory.CreateDirectory($"{destPath}{srcInfo.FullName[srcPath.FullName.Length..]}"));
      Parallel.ForEach(srcPath.GetFiles("*", SearchOption.AllDirectories), 
        srcInfo => File.Copy(srcInfo.FullName, $"{destPath}{srcInfo.FullName[srcPath.FullName.Length..]}", true));
      });
    }

  }
}

使用方法:

new DirectoryInfo(sourcePath).CopyTo(destinationPath);

复制自MSDN:

using System;
using System.IO;

class CopyDir
{
    public static void Copy(string sourceDirectory, string targetDirectory)
    {
        DirectoryInfo diSource = new DirectoryInfo(sourceDirectory);
        DirectoryInfo diTarget = new DirectoryInfo(targetDirectory);

        CopyAll(diSource, diTarget);
    }

    public static void CopyAll(DirectoryInfo source, DirectoryInfo target)
    {
        Directory.CreateDirectory(target.FullName);

        // Copy each file into the new directory.
        foreach (FileInfo fi in source.GetFiles())
        {
            Console.WriteLine(@"Copying {0}\{1}", target.FullName, fi.Name);
            fi.CopyTo(Path.Combine(target.FullName, fi.Name), true);
        }

        // Copy each subdirectory using recursion.
        foreach (DirectoryInfo diSourceSubDir in source.GetDirectories())
        {
            DirectoryInfo nextTargetSubDir =
                target.CreateSubdirectory(diSourceSubDir.Name);
            CopyAll(diSourceSubDir, nextTargetSubDir);
        }
    }

    public static void Main()
    {
        string sourceDirectory = @"c:\sourceDirectory";
        string targetDirectory = @"c:\targetDirectory";

        Copy(sourceDirectory, targetDirectory);
    }

    // Output will vary based on the contents of the source directory.
}

抱歉之前的代码，它仍然有bug:((成为最快枪问题的猎物)。这里是测试和工作。键是SearchOption。AllDirectories，这消除了显式递归的需要。

string path = "C:\\a";
string[] dirs = Directory.GetDirectories(path, "*.*", SearchOption.AllDirectories);
string newpath = "C:\\x";
try
{
    Directory.CreateDirectory(newpath);
}
catch (IOException ex)
{
    Console.WriteLine(ex.Message);
}
for (int j = 0; j < dirs.Length; j++)
{
    try
    {
        Directory.CreateDirectory(dirs[j].Replace(path, newpath));
    }
    catch (IOException ex)
    {
        Console.WriteLine(ex.Message);
    }
}

string[] files = Directory.GetFiles(path, "*.*", SearchOption.AllDirectories);
for (int j = 0; j < files.Length; j++)            
{
    try
    {
        File.Copy(files[j], files[j].Replace(path, newpath));
    }
    catch (IOException ex)
    {
        Console.WriteLine(ex.Message);
    }
}

比任何代码都好(使用递归扩展DirectoryInfo的方法)

public static bool CopyTo(this DirectoryInfo source, string destination)
    {
        try
        {
            foreach (string dirPath in Directory.GetDirectories(source.FullName))
            {
                var newDirPath = dirPath.Replace(source.FullName, destination);
                Directory.CreateDirectory(newDirPath);
                new DirectoryInfo(dirPath).CopyTo(newDirPath);
            }
            //Copy all the files & Replaces any files with the same name
            foreach (string filePath in Directory.GetFiles(source.FullName))
            {
                File.Copy(filePath, filePath.Replace(source.FullName,destination), true);
            }
            return true;
        }
        catch (IOException exp)
        {
            return false;
        }
    }

下面是一个DirectoryInfo的扩展方法。CopyTo(注意overwrite参数):

public static DirectoryInfo CopyTo(this DirectoryInfo sourceDir, string destinationPath, bool overwrite = false)
{
    var sourcePath = sourceDir.FullName;

    var destination = new DirectoryInfo(destinationPath);

    destination.Create();

    foreach (var sourceSubDirPath in Directory.EnumerateDirectories(sourcePath, "*", SearchOption.AllDirectories))
        Directory.CreateDirectory(sourceSubDirPath.Replace(sourcePath, destinationPath));

    foreach (var file in Directory.EnumerateFiles(sourcePath, "*", SearchOption.AllDirectories))
        File.Copy(file, file.Replace(sourcePath, destinationPath), overwrite);

    return destination;
}

你可以一直使用这个，摘自微软网站。

static void Main()
{
    // Copy from the current directory, include subdirectories.
    DirectoryCopy(".", @".\temp", true);
}

private static void DirectoryCopy(string sourceDirName, string destDirName, bool copySubDirs)
{
    // Get the subdirectories for the specified directory.
    DirectoryInfo dir = new DirectoryInfo(sourceDirName);

    if (!dir.Exists)
    {
        throw new DirectoryNotFoundException(
            "Source directory does not exist or could not be found: "
            + sourceDirName);
    }

    DirectoryInfo[] dirs = dir.GetDirectories();
    // If the destination directory doesn't exist, create it.
    if (!Directory.Exists(destDirName))
    {
        Directory.CreateDirectory(destDirName);
    }

    // Get the files in the directory and copy them to the new location.
    FileInfo[] files = dir.GetFiles();
    foreach (FileInfo file in files)
    {
        string temppath = Path.Combine(destDirName, file.Name);
        file.CopyTo(temppath, false);
    }

    // If copying subdirectories, copy them and their contents to new location.
    if (copySubDirs)
    {
        foreach (DirectoryInfo subdir in dirs)
        {
            string temppath = Path.Combine(destDirName, subdir.Name);
            DirectoryCopy(subdir.FullName, temppath, copySubDirs);
        }
    }
}