C#开发小经验分享之一文件操作

1.文件操作

System.IO.Directory.GetFiles("*.xml").ToList().ForEach(p => { "dosomething here" });

1-1.按照行读取文件数据

原始文件
aa
bb
cc
dd
jj
gg

StreamReader sr = new StreamReader(@"C:\1.txt");

string strContent= sr.ReadToEnd();

string[] strArr = strContent.Split('\n');

得到的是单行数据

1-2.获取根目录
AppDomain.CurrentDomain.BaseDirectory得到程序当前运行中根目录

1-3.linq xml中的Descendants()遍历根节点下所有子节点的集合
例如:
<A>
  <B>
    <C>
      <d></d>
      <e></e>
    </C>
  </B>
</A>
A.Descendants()结果为 B
A.Descendants().Descendants()结果为C
A.Descendants().Descendants().Descendants()结果为  d,e

1-3.文件是否被占用api函数
        [DllImport("kernel32.dll")]
        public static extern IntPtr _lopen(string lpPathName, int iReadWrite);
        [DllImport("kernel32.dll")]
        public static extern bool CloseHandle(IntPtr hObject);
        public const int OF_READWRITE = 2;
        public const int OF_SHARE_DENY_NONE = 0x40;
        public readonly IntPtr HFILE_ERROR = new IntPtr(-1);
        private void button1_Click(object sender, EventArgs e)
        {
            string vFileName = @"c:\1.xml";
            if (!File.Exists(vFileName))
            {
                MessageBox.Show("文件都不存在!");
                return;
            }
            IntPtr vHandle = _lopen(vFileName, OF_READWRITE | OF_SHARE_DENY_NONE);
            if (vHandle == HFILE_ERROR)
            {
                MessageBox.Show("文件被占用！");
                return;
            }
            CloseHandle(vHandle);
            MessageBox.Show("没有被占用！");
        }

1-4.图片和base64互相转换

 /// <summary>
        /// 图片转换成字节流
        /// </summary>
        /// <param name="img">要转换的Image对象</param>
        /// <returns>转换后返回的字节流</returns>
        public static byte[] ImgToByt(System.Drawing.Image img)
        {
            MemoryStream ms = new MemoryStream();
            byte[] imagedata = null;
            img.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
            imagedata = ms.GetBuffer();
            return imagedata;
        }
        /// <summary>
        /// 字节流转换成图片
        /// </summary>
        /// <param name="byt">要转换的字节流</param>
        /// <returns>转换得到的Image对象</returns>
        public static System.Drawing.Image BytToImg(byte[] byt, string imgUrl)
        {
            MemoryStream ms = new MemoryStream(byt);

            System.Drawing.Image img = System.Drawing.Image.FromStream(ms);
            img.Save(imgUrl);
            return img;
        }
        //
        /// <summary>
        /// 根据图片路径返回图片的字节流byte[]
        /// </summary>
        /// <param name="imagePath">图片路径</param>
        /// <returns>返回的字节流</returns>
        public static byte[] getImageByte(string imagePath)
        {
            FileStream files = new FileStream(imagePath, FileMode.Open);
            byte[] imgByte = new byte[files.Length];
            files.Read(imgByte, 0, imgByte.Length);
            files.Close();
            return imgByte;
        }

1-5 遍历文件夹下的文件夹

 public static void GetAllDirList(string strBaseDir)
       {
           DirectoryInfo di = new DirectoryInfo(strBaseDir);
           DirectoryInfo[] diA = di.GetDirectories();
           for (int i = 0; i < diA.Length; i++)
           {
               al.Add(diA[i].FullName);
               //diA[i].FullName是某个子目录的绝对地址，把它记录在ArrayList中
               GetAllDirList(diA[i].FullName);

           }

       }

1-6 判断文件是否被占用

        [DllImport("kernel32.dll")]
        public static extern IntPtr _lopen(string lpPathName, int iReadWrite);
        [DllImport("kernel32.dll")]
        public static extern bool CloseHandle(IntPtr hObject);
        public const int OF_READWRITE = 2;
        public const int OF_SHARE_DENY_NONE = 0x40;
        public readonly IntPtr HFILE_ERROR = new IntPtr(-1);
        private void button1_Click(object sender, EventArgs e)
        {
            string vFileName = @"c:\1.xml";
            if (!File.Exists(vFileName))
            {
                MessageBox.Show("文件都不存在!");
                return;
            }
            IntPtr vHandle = _lopen(vFileName, OF_READWRITE | OF_SHARE_DENY_NONE);
            if (vHandle == HFILE_ERROR)
            {
                MessageBox.Show("文件被占用！");
                return;
            }
            CloseHandle(vHandle);
            MessageBox.Show("没有被占用！");
        }

1-7