1、文件：
File.Create(path)
File.Copy(sourceFile,destFile,true);
File.Move(sourceFile,targetFile)
File.Exists(fileName)
File.Delete(fileName)
FileInfo fi = new FileInfo(fileName);
fi.Delete();
2、文件夹：
Directory.CreateDirectory(targetPath);
Directory.Exists(path)
Directory.Delete(path)
Directory.Move(sourcePath, targetPath);
DirectoryInfo di = new DirectoryInfo(path);
di.Delete(true);
3、文件夹拷贝需要遍历，逐个拷贝文件。
