C# 操作文件常用的方法

/// <summary>
    /// 文件转byte[]
    /// </summary>
    /// <param name="Path">绝对路径</param>
    /// <returns>byte[]</returns>
    public static byte[] FileToBytes(string Path)
    {
        if (!System.IO.File.Exists(Path))
            return new byte[0];

        FileInfo fi = new FileInfo(Path);
        byte[] buff = new byte[fi.Length];

        FileStream fs = fi.OpenRead();
        fs.Read(buff, 0, Convert.ToInt32(fs.Length));
        fs.Close();

        return buff;
    }

    /// <summary>
    /// 文件转Base64
    /// </summary>
    /// <param name="Path">绝对路径</param>
    /// <returns>Base64</returns>
    public static string FileToBase64(string Path)
    {
        if (!System.IO.File.Exists(Path))
            return string.Empty;

        FileInfo fi = new FileInfo(Path);
        byte[] buff = new byte[fi.Length];

        FileStream fs = fi.OpenRead();
        fs.Read(buff, 0, Convert.ToInt32(fs.Length));
        fs.Close();

        return BytesToBase64(buff);
    }

    /// <summary>
    /// byte[]转Base64
    /// </summary>
    /// <param name="buff">byte[]</param>
    /// <returns>转Base64</returns>
    public static string BytesToBase64(byte[] buff)
    {
        return System.Text.Encoding.UTF8.GetString(buff);
    }

    /// <summary>
    /// Base64转byte[]
    /// </summary>
    /// <param name="Base64">转Base64</param>
    /// <returns>byte[]</returns>
    public static byte[] Base64ToBytes(string Base64)
    {
        return System.Text.Encoding.UTF8.GetBytes(Base64);
    }

    /// <summary>
    /// byte[]转文件保存指定地址
    /// </summary>
    /// <param name="buff">byte数组</param>
    /// <param name="SavePath">保存地址</param>
    /// <param name="FileName">文件名</param>
    /// <param name="Open">是否打开文件</param>
    public static void BytesToFile(byte[] buff, string SavePath, string FileName, bool Open = false)
    {
        //如果不存在就创建Enclosure文件夹 
        if (Directory.Exists(SavePath) == false)
            Directory.CreateDirectory(SavePath);

        if (System.IO.File.Exists(SavePath + @"\" + FileName))
            System.IO.File.Delete(SavePath + @"\" + FileName);


        FileStream fs = new FileStream(SavePath + @"\" + FileName, FileMode.CreateNew);
        BinaryWriter bw = new BinaryWriter(fs);
        bw.Write(buff, 0, buff.Length);
        bw.Close();
        fs.Close();

        if (Open)
        {
            //创建要运行的文件或者程序
            var startfile = new ProcessStartInfo
            {
                FileName = SavePath + @"\" + FileName,//文件完全路径
                WindowStyle = ProcessWindowStyle.Normal,//Windows窗口样式
                UseShellExecute = true//为true，则用默认的打开方式打开
            };
            //创建Process命令
            var cmd = new Process();
            cmd.StartInfo = startfile;
            cmd.Start(); //打开文件
        }
    }

    /// <summary>
    /// Base64转文件保存指定地址
    /// </summary>
    /// <param name="Base64">Base64</param>
    /// <param name="SavePath">保存地址</param>
    /// <param name="FileName">文件名</param>
    public static void Base64ToFile(string Base64, string SavePath, string FileName, bool Open = false)
    {
        //如果不存在就创建Enclosure文件夹 
        if (Directory.Exists(SavePath) == false)
            Directory.CreateDirectory(SavePath);

        if (System.IO.File.Exists(SavePath + @"\" + FileName))
            System.IO.File.Delete(SavePath + @"\" + FileName);

        byte[] buff = Base64ToBytes(Base64);
        FileStream fs = new FileStream(SavePath + @"\" + FileName, FileMode.CreateNew);
        BinaryWriter bw = new BinaryWriter(fs);
        bw.Write(buff, 0, buff.Length);
        bw.Close();
        fs.Close();

        if (Open)
        {
            //创建要运行的文件或者程序
            var startfile = new ProcessStartInfo
            {
                FileName = SavePath + @"\" + FileName,//文件完全路径
                WindowStyle = ProcessWindowStyle.Normal,//Windows窗口样式
                UseShellExecute = true//为true，则用默认的打开方式打开
            };
            //创建Process命令
            var cmd = new Process();
            cmd.StartInfo = startfile;
            cmd.Start(); //打开文件
        }
    }

    /// <summary>
    /// Stream转File
    /// </summary>
    /// <param name="stream">Stream</param>
    /// <param name="fileName">绝对路径</param>
    public static void StreamToFile(Stream stream, string SavePath, string FileName, bool Open = false)
    {
        //如果不存在就创建Enclosure文件夹 
        if (Directory.Exists(SavePath) == false)
            Directory.CreateDirectory(SavePath);

        if (System.IO.File.Exists(SavePath + @"\" + FileName))
            System.IO.File.Delete(SavePath + @"\" + FileName);

        // 把 Stream 转换成 byte[]
        byte[] bytes = new byte[stream.Length];
        stream.Read(bytes, 0, bytes.Length);
        // 设置当前流的位置为流的开始
        stream.Seek(0, SeekOrigin.Begin);
        // 把 byte[] 写入文件
        FileStream fs = new FileStream(SavePath + @"\" + FileName, FileMode.Create);
        BinaryWriter bw = new BinaryWriter(fs);
        bw.Write(bytes);
        bw.Close();
        fs.Close();

        if (Open)
        {
            //创建要运行的文件或者程序
            var startfile = new ProcessStartInfo
            {
                FileName = SavePath + @"\" + FileName,//文件完全路径
                WindowStyle = ProcessWindowStyle.Normal,//Windows窗口样式
                UseShellExecute = true//为true，则用默认的打开方式打开
            };
            //创建Process命令
            var cmd = new Process();
            cmd.StartInfo = startfile;
            cmd.Start(); //打开文件
        }
    }

    /// <summary>
    /// byte[]转System.Drawing.Image
    /// </summary>
    /// <param name="buffer">byte[]</param>
    /// <returns>System.Drawing.Image</returns>
    public static Image ByteToImage(byte[] buffer)
    {
        MemoryStream ms = new MemoryStream(buffer);
        ms.Position = 0;
        Image img = Image.FromStream(ms);
        ms.Close();
        return img;
    }

    /// <summary>
    /// System.Drawing.Bitmap转byte[]
    /// </summary>
    /// <param name="Bit">System.Drawing.Bitmap</param>
    /// <param name="format">图片格式</param>
    /// <returns>byte[]</returns>
    public static byte[] ByteToBitmap(Bitmap Bitmap, ImageFormat format)
    {
        byte[] back = null;
        MemoryStream ms = new MemoryStream();
        Bitmap.Save(ms, format);
        back = ms.GetBuffer();
        ms.Dispose();
        return back;
    }

    /// <summary>
    /// byte[]转内存流MemoryStream
    /// </summary>
    /// <param name="buff">byte[]</param>
    /// <returns>MemoryStream</returns>
    public static MemoryStream ByteToMemoryStream(byte[] buff)
    {
        return new MemoryStream(buff);
    }

    /// <summary>
    /// 内存流MemoryStream转byte[]
    /// </summary>
    /// <param name="outStream">MemoryStream</param>
    /// <returns>byte[]</returns>
    public static byte[] MemoryStreamToByte(MemoryStream outStream)
    {
        return outStream.ToArray();
    }

    /// <summary>
    /// 流Stream转byte[]
    /// </summary>
    /// <param name="stream">Stream</param>
    /// <returns>byte[]</returns>
    public byte[] StreamToByte(Stream stream)
    {
        byte[] bytes = new byte[stream.Length];
        stream.Read(bytes, 0, bytes.Length);
        // 设置当前流的位置为流的开始
        stream.Seek(0, SeekOrigin.Begin);
        return bytes;
    }

    /// <summary>
    /// byte[]转Stream流
    /// </summary>
    /// <param name="bytes">byte[]</param>
    /// <returns>Stream</returns>
    public Stream ByteToStream(byte[] bytes)
    {
        return new MemoryStream(bytes);
    }

    //从文件读取 Stream
    /// <summary>
    /// 文件转Stream流
    /// </summary>
    /// <param name="FileName">绝对路径</param>
    /// <returns>Stream流</returns>
    public Stream FileToStream(string FileName)
    {
        // 打开文件
        FileStream fileStream = new FileStream(FileName, FileMode.Open, FileAccess.Read, FileShare.Read);
        // 读取文件的 byte[]
        byte[] bytes = new byte[fileStream.Length];
        fileStream.Read(bytes, 0, bytes.Length);
        fileStream.Dispose();
        fileStream.Close();
        // 把 byte[] 转换成 Stream
        Stream stream = new MemoryStream(bytes);
        return stream;
    }