asp.net:GDI+ 中发生一般错误

asp.net : A generic error occurred in GDI+(asp.net:GDI+ 中发生一般错误)

问题描述

我创建了一个 asp.net 4.0 Web 应用程序，它具有用于上传图像的 Web 服务.我通过将 Base64 字符串形式的图像从我的移动应用程序发送到 Web 服务来上传图像.

I create an asp.net 4.0 web application which has a web service for uploading images. I am uploading images by sending the image in form of Base64 string from my mobile app to the web service.

以下是我的代码:

public string Authenticate(string username, string password, string fileID, string imageData)
    {
        Dictionary<string, string> responseDictionary = new Dictionary<string, string>();
        bool isAuthenticated = true; // Set this value based on the authentication logic

        try
        {
            if (isAuthenticated)
            {
                UploadImage(imageData);

                string result = "success";
                var message = "Login successful";

                responseDictionary["status"] = result;
                responseDictionary["message"] = message;
            }
        }
        catch (Exception ex)
        {

            responseDictionary["status"] = ex.Message;
            responseDictionary["message"] = ex.StackTrace;
        }

        return new JavaScriptSerializer().Serialize(responseDictionary);
    }

    private void UploadImage(string uploadedImage)
    {
        // Convert Base64 String to byte[]
        byte[] imageBytes = Convert.FromBase64String(uploadedImage);
        MemoryStream ms = new MemoryStream(imageBytes, 0, imageBytes.Length);

        System.Drawing.Bitmap bitmap = (System.Drawing.Bitmap)Image.FromStream(ms);

        string uploadPath = Server.MapPath("..\uploads\") + DateTime.Now.Ticks.ToString() + ".jpeg";
        ms.Close();

        bitmap.Save(uploadPath, System.Drawing.Imaging.ImageFormat.Jpeg);
        bitmap.Dispose();
    }    

这段代码在我的本地 ASP.NET 开发服务器上运行良好，我能够在我的上传"目录中看到上传的图像.但是，将代码传输到 FTP 目录后，我现在收到以下错误:

This code was working fine on my local ASP.NET development server and I was able to see the uploaded image in my "uploads" directory. However, after transferring the code to the FTP directory, I am now getting the following error:

GDI+ 中发生一般错误

我通过创建一个虚拟的 .aspx 页面并在 page_load 上创建一个文本文件来检查上传目录是否具有适当的权限，并且它工作正常.

I have checked that the upload directory has proper permission by creating a dummy .aspx page and creating a text file on page_load, and it works fine.

即使在谷歌搜索之后，我也无法解决这个问题.谁能帮我解决这个问题?

Even after doing google search, I was not able to solve this problem. Can anybody help me fixing this?

非常感谢.

推荐答案

不要直接写入文件，而是将位图保存到 MemoryStream，然后将流的内容保存到磁盘.这是一个古老的已知问题，坦率地说，我不记得为什么会这样的所有细节.

Instead of writing directly to files, save your bitmap to a MemoryStream and then save the contents of the stream to disk. This is an old, known issue and, frankly, I don't remember all the details why this is so.

 MemoryStream mOutput = new MemoryStream();
 bmp.Save( mOutput, ImageFormat.Png );
 byte[] array = mOutput.ToArray();

 // do whatever you want with the byte[]

在你的情况下，它可能是

In your case it could be either

private void UploadImage(string uploadedImage)
{
    // Convert Base64 String to byte[]
    byte[] imageBytes = Convert.FromBase64String(uploadedImage);

    string uploadPath = Server.MapPath("..\uploads\") + DateTime.Now.Ticks.ToString() + ".jpeg";

    // store the byte[] directly, without converting to Bitmap first 
    using ( FileStream fs = File.Create( uploadPath ) )
    using ( BinaryWriter bw = new BinaryWriter( fs ) )
       bw.Write( imageBytes );
}    

或

private void UploadImage(string uploadedImage)
{
    // Convert Base64 String to byte[]
    byte[] imageBytes = Convert.FromBase64String(uploadedImage);
    MemoryStream ms = new MemoryStream(imageBytes, 0, imageBytes.Length);

    System.Drawing.Bitmap bitmap = (System.Drawing.Bitmap)Image.FromStream(ms);

    string uploadPath = Server.MapPath("..\uploads\") + DateTime.Now.Ticks.ToString() + ".jpeg";
    ms.Close();

    // convert to image first and store it to disk
    using ( MemoryStream mOutput = new MemoryStream() )
    {  
        bitmap.Save( mOutput, System.Drawing.Imaging.ImageFormat.Jpeg);
        using ( FileStream fs = File.Create( uploadPath ) )
        using ( BinaryWriter bw = new BinaryWriter( fs ) )
            bw.Write( mOutput.ToArray() );
    }
}    

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