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);

使用这个类。

public static class Extensions
{
    public static void CopyTo(this DirectoryInfo source, DirectoryInfo target, bool overwiteFiles = true)
    {
        if (!source.Exists) return;
        if (!target.Exists) target.Create();

        Parallel.ForEach(source.GetDirectories(), (sourceChildDirectory) => 
            CopyTo(sourceChildDirectory, new DirectoryInfo(Path.Combine(target.FullName, sourceChildDirectory.Name))));

        foreach (var sourceFile in source.GetFiles())
            sourceFile.CopyTo(Path.Combine(target.FullName, sourceFile.Name), overwiteFiles);
    }
    public static void CopyTo(this DirectoryInfo source, string target, bool overwiteFiles = true)
    {
        CopyTo(source, new DirectoryInfo(target), overwiteFiles);
    }
}

public static class Extensions
{
    public static void Copy(this DirectoryInfo self, DirectoryInfo destination, bool recursively)
    {
        foreach (var file in self.GetFiles())
        {
            file.CopyTo(Path.Combine(destination.FullName, file.Name));
        }

        if (recursively)
        {
            foreach (var directory in self.GetDirectories())
            {
                directory.Copy(destination.CreateSubdirectory(directory.Name), recursively);
            }
        }
    }
}

使用示例:

var sourceDirectory = new DirectoryInfo(@"C:\source");
var destinationDirectory = new DirectoryInfo(@"C:\destination");

if (destinationDirectory.Exists == false)
{
    sourceDirectory.Copy(destinationDirectory, recursively: true);
}

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;
        }
    }

下面的代码复制所有文件从源到目标给定的模式在相同的文件夹结构:

public static void Copy()
        {
            string sourceDir = @"C:\test\source\";
            string destination = @"C:\test\destination\";

            string[] textFiles = Directory.GetFiles(sourceDir, "*.txt", SearchOption.AllDirectories);

            foreach (string textFile in textFiles)
            {
                string fileName = textFile.Substring(sourceDir.Length);
                string directoryPath = Path.Combine(destination, Path.GetDirectoryName(fileName));
                if (!Directory.Exists(directoryPath))
                    Directory.CreateDirectory(directoryPath);

                File.Copy(textFile, Path.Combine(directoryPath, Path.GetFileName(textFile)), true);
            }
        }

我的解决方案基本上是对@Termininja的答案的修改，但我增强了一点，它似乎比公认的答案快5倍以上。

public static void CopyEntireDirectory(string path, string newPath)
{
    Parallel.ForEach(Directory.GetFileSystemEntries(path, "*", SearchOption.AllDirectories)
    ,(fileName) =>
    {
        string output = Regex.Replace(fileName, "^" + Regex.Escape(path), newPath);
        if (File.Exists(fileName))
        {
            Directory.CreateDirectory(Path.GetDirectoryName(output));
            File.Copy(fileName, output, true);
        }
        else
            Directory.CreateDirectory(output);
    });
}

编辑:将@Ahmed Sabry修改为完全并行foreach确实会产生更好的结果，但是代码使用递归函数，在某些情况下并不理想。

public static void CopyEntireDirectory(DirectoryInfo source, DirectoryInfo target, bool overwiteFiles = true)
{
    if (!source.Exists) return;
    if (!target.Exists) target.Create();

    Parallel.ForEach(source.GetDirectories(), (sourceChildDirectory) =>
        CopyEntireDirectory(sourceChildDirectory, new DirectoryInfo(Path.Combine(target.FullName, sourceChildDirectory.Name))));

    Parallel.ForEach(source.GetFiles(), sourceFile =>
        sourceFile.CopyTo(Path.Combine(target.FullName, sourceFile.Name), overwiteFiles));
}