C# 删除文件错误 access denied

　　　　　　if (backupPathDir.Exists) {
                System.IO.DirectoryInfo di = new DirectoryInfo(backupPathDir.ToString());

                foreach (FileInfo file in di.GetFiles()) {
                    file.Attributes = FileAttributes.Normal;
                    file.Delete();
                }
                foreach (DirectoryInfo dir in di.GetDirectories()) {
                    dir.Delete(true);
                }
                backupPathDir.Delete(true);
            }

Delete

File.SetAttributes(file, FileAttributes.Normal);
File.Delete(file);


Copy

File.Copy(file, dest, true);
File.SetAttributes(dest, FileAttributes.Normal);