protected void Button1_Click(object sender, EventArgs e)
{
  //圖片轉(zhuǎn)二進制
  byte[] imageByte = GetPictureData(Server.MapPath("./uploadfile/111.png"));
  //二進制轉(zhuǎn)換成字符串
  string picStr = Convert.ToBase64String(imageByte);
  //輸出字符串
  Response.Write(picStr);
  //字符串轉(zhuǎn)二進制
  byte[] imageBytes = Convert.FromBase64String(picStr);
  //讀入MemoryStream對象
  MemoryStream memoryStream = new MemoryStream(imageBytes, 0, imageBytes.Length);
  memoryStream.Write(imageBytes, 0, imageBytes.Length);
  //二進制轉(zhuǎn)成圖片保存
  System.Drawing.Image image = System.Drawing.Image.FromStream(memoryStream);
  image.Save(Server.MapPath("./uploadfile/222.png"));
}
/// <summary>
/// 二進制流轉(zhuǎn)圖片
/// </summary>
/// <param name="streamByte">二進制流</param>
/// <returns>圖片</returns>
public System.Drawing.Image ReturnPhoto(byte[] streamByte)
{
  System.IO.MemoryStream ms = new System.IO.MemoryStream(streamByte);
  System.Drawing.Image img = System.Drawing.Image.FromStream(ms);
  return img;
}
/// <summary>
/// 圖片轉(zhuǎn)二進制
/// </summary>
/// <param name="imagepath">圖片地址</param>
/// <returns>二進制</returns>
public byte[] GetPictureData(string imagepath)
{
  //根據(jù)圖片文件的路徑使用文件流打開，并保存為byte[]
  FileStream fs = new FileStream(imagepath, FileMode.Open);//可以是其他重載方法
  byte[] byData = new byte[fs.Length];
  fs.Read(byData, 0, byData.Length);
  fs.Close();
  return byData;
}
/// <summary>
/// 圖片轉(zhuǎn)二進制
/// </summary>
/// <param name="imgPhoto">圖片對象</param>
/// <returns>二進制</returns>
public byte[] PhotoImageInsert(System.Drawing.Image imgPhoto)
{
  //將Image轉(zhuǎn)換成流數(shù)據(jù)，并保存為byte[]
  MemoryStream mstream = new MemoryStream();
  imgPhoto.Save(mstream, System.Drawing.Imaging.ImageFormat.Bmp);
  byte[] byData = new Byte[mstream.Length];
  mstream.Position = 0;
  mstream.Read(byData, 0, byData.Length);
  mstream.Close();
  return byData;
}