C#通过递归实现文件及文件夹拷贝

         //获得长路径的相对短路径名称
        [DllImport("kernel32.dll",CharSet = CharSet.Auto)]
        public static extern uint GetShortPathName(string lpszLongPath,StringBuilder lpszShortPath,int cchBuffer);
        //实现文件拷贝，递归逐文件拷贝
        private void DirectoryCopy(string sourceDir,string targetDir)
        {
             
 
            if (!Directory.Exists(sourceDir))
            {
                DialogResult OKButtonDown = MessageBox.Show("需要备份的路径不存在，请查看！","备份失败",MessageBoxButtons.OK,MessageBoxIcon.Warning);
                if (DialogResult.OK == OKButtonDown)
                {
                    Application.Exit();
                }
            }
             
            string sourceFolderName = sourceDir.Replace(Directory.GetParent(sourceDir).ToString(),"").Replace(Path.DirectorySeparatorChar.ToString(),"");
 
            if (sourceDir == targetDir + sourceFolderName)
            {
                DialogResult OKButtonDown = MessageBox.Show("备份的目标路径和原路径相同，不需要备份！",MessageBoxIcon.Warning);
                if (DialogResult.OK == OKButtonDown)
                {
                    Application.Exit();
                }
  
            }
 
            //得到要复制到的路径
            string tagetPath = targetDir + Path.DirectorySeparatorChar.ToString() + sourceFolderName;
 
 
            //检查目标路径
            if (Directory.Exists(tagetPath))
            {
                DialogResult OKButtonDown = MessageBox.Show("备份的目标路径已经存在，点击是将删除目标并备份，点击否将覆盖并备份","请查看",MessageBoxButtons.YesNoCancel,MessageBoxIcon.Warning);
                if (DialogResult.Yes == OKButtonDown)
                {
                    Directory.Delete(tagetPath,true);
                    //return;
                }
                else if (DialogResult.No == OKButtonDown)
                {
                    //复制文件
                    string[] files1 = Directory.GetFiles(sourceDir);
                    for (int i = 0; i < files1.Length; i++)
                    {
 
                        File.Copy(files1[i],tagetPath + Path.DirectorySeparatorChar.ToString() + Path.GetFileName(files1[i]),true);
                    }
                    //复制目录
                    string[] dires1 = Directory.GetDirectories(sourceDir);
                    for (int j = 0; j < dires1.Length; j++)
                    {
                        DirectoryCopy(dires1[j],tagetPath);
                    }
                    return;
                }
                else if (DialogResult.Cancel == OKButtonDown)
                {
                    Application.Exit();
 
                }
 
            }
            
            StringBuilder _shortPath1 = new StringBuilder(255);
            uint result1 = GetShortPathName(tagetPath,_shortPath1,255);
            string MyShortPath1 = _shortPath1.ToString();
            if (0 == result1)
            {
                Directory.CreateDirectory(tagetPath);
            }
            else
            {
                Directory.CreateDirectory(MyShortPath1);
            }
            //复制文件
            string[] files3 = Directory.GetFiles(sourceDir);
            for (int i = 0; i < files3.Length; i++)
            {
                //string longPath = tagetPath + Path.DirectorySeparatorChar.ToString() + Path.GetFileName(files3[i]);
                //StringBuilder _shortPath = new StringBuilder(255);
                //uint result = GetShortPathName(longPath,_shortPath,255);
                //string MyShortPath = _shortPath.ToString();
                File.Copy(files3[i],/*MyShortPath/tagetPath + Path.DirectorySeparatorChar.ToString() + Path.GetFileName(files3[i]),true);
            }
            //复制目录
            string[] dires3 = Directory.GetDirectories(sourceDir);
            for (int j = 0; j < dires3.Length; j++)
            {
                string longPath = dires3[j];
                StringBuilder _shortPath = new StringBuilder(255);
                uint result = GetShortPathName(longPath,255);
                string MyShortPath = _shortPath.ToString();
 
                DirectoryCopy(MyShortPath,tagetPath);
            }
        }