Question

我要求用户上传图片，可以是任何图片格式。

我将base64数据传递给我的.Net控制器，以及文件名（从中我可以获得扩展名）。

然后我将该base64字符串转换为Image。

    public static Image Base64ToImage(string base64String)
    {

        // Convert base 64 string to byte[]
        byte[] imageBytes = Convert.FromBase64String(base64String);
        // Convert byte[] to Image
        using (var ms = new MemoryStream(imageBytes, 0, imageBytes.Length))
        {
            Image image = Image.FromStream(ms, true);
            return image;
        }
    }

我收到错误：

输入不是有效的Base-64字符串，因为它包含非基本64个字符，两个以上的填充字符或填充字符中的非法字符

我认为这是因为base54字符串有：

“data：image / jpeg; base64，/ 9j / 4AAQSkZJRgABA ....”一开始。

所以我需要修剪“data：image / jpeg; base64”，然后保存它？在删除有关文件类型的数据时，是否需要在其他位置指定它？

我发现的所有例子似乎都没有从前面修剪任何东西。他们只是保存字符串。我猜，我身边的东西是添加标题？

Answer 1

嗨请查看我过去使用的工作转换器版本，请告诉您是否需要更多解释。

似乎你转换为base64是罪魁祸首！

       /// <summary>
    ///1 Convert String to Image
    /// </summary>
    /// <param name="commands"></param>
    /// <returns></returns>

    public Image ConvertStringtoImage(string commands)
    {

        byte[] photoarray = Convert.FromBase64String(commands);
        MemoryStream ms = new MemoryStream(photoarray, 0, photoarray.Length);
        ms.Write(photoarray, 0, photoarray.Length);
        Image image = System.Drawing.Image.FromStream(ms);
        return image;

    }


    /// <summary>
    ///2. Read picture from Database and return as image
    /// just change the mysql to sql server type.
    /// </summary>
    /// <param name="commands"></param>
    /// <returns></returns>

    public Image Readphotofromdb(string commands)
    {
        Image image = null;
        using (MySqlConnection dbConn = new MySqlConnection(connector))
        {
            using (MySqlCommand cmd = new MySqlCommand(commands, dbConn))
            {
                dbConn.Open();
                using (MySqlDataReader reader = cmd.ExecuteReader())
                {
                    if (reader.Read())
                    {
                        byte[] photoarray = Convert.FromBase64String(reader.GetString(0));
                        MemoryStream ms = new MemoryStream(photoarray, 0, photoarray.Length);
                        ms.Write(photoarray, 0, photoarray.Length);
                        image = new Bitmap(ms);

                    }
                }
            }
        }
        MySqlConnection.ClearAllPools();
        return image;

    }

    /// <summary>
    /// 3. Convert Image to base64 string
    /// </summary>
    /// <param name="image"></param>
    /// <returns></returns>


    public string ConvertImageToString(Image image)
    {
        byte[] byteArray = new byte[0];
        using (MemoryStream stream = new MemoryStream())
        {
            image.Save(stream, System.Drawing.Imaging.ImageFormat.Png);
            stream.Close();
            byteArray = stream.ToArray();
        }
        string base64String = Convert.ToBase64String(byteArray);
        return base64String;
    }

Answer 2

使用类似的图像数据 /9j/4AAQSkZJRgABAgAAAQABAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQ......9=代替数据：image / jpeg; base64，/ 9j / 4AAQSkZJRgABAgAAAQABAAD / 2wBDAAgGBgcGBQgHBwcJCQgKDBQ .. .... 9 =

 private void GetImage(){
  string imagedata="/9j/4AAQSkZJRgABAgAAAQABAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQ.. 
   ....9=";
  Image image=ImageFromBase64(imagedata);
}
public static Image ImageFromBase64(string base64String)
    {
                
        byte[] imageBytes = Convert.FromBase64String(base64String);
         
        using (var ms = new MemoryStream(imageBytes, 0, imageBytes.Length))
        {
            Image image = Image.FromStream(ms, true);
            return image;
        }
    }

从Base64到Image的图像

2 个答案: