在MVC3中从列表到Web页面显示Blob图像对象

Question

I am working on a project where I load 12 long blob images from a database and save them in a list.

In the html page, i have to display the images but i am getting errors when trying to convert a blob to an image.

I get the error Parameter is not valid when using memory stream. No matter whatever change I make, unable to get rid of that error.

Below is the code:

    public Image getProduct_Image(byte[] imagebytes)
    {
        byte[] byteArray = new byte[imagebytes.Length];

        MemoryStream ms = new MemoryStream(byteArray);
        ms.Position = 0;

        ms.Read((byteArray, 0, byteArray.Length);
        ms.ToArray();
        ms.Seek(0, SeekOrigin.Begin);
        System.Drawing.Image returnImage = Image.FromStream((Stream) ms);
             Bitmap bmp = new Bitmap(returnImage);
             return bmp;
    }

Answer 1

Expanding on my comment:

You can write images from bytes into HTML in a few lines of code with an .ashx handler, but since you're using MVC, it's actually really easy.

First you just set up a controller action - assume your image is identifiable based on an integer ID. It's just a single line to return those bytes as content.

public FileContentResult SomeImage(int id)
{
    byte[] bytes = GetImageBytesFromDatabase(id);
    return File(bytes, "image/jpeg");
}

Your markup is just an image tag with the source as this controller action:

<img src="@Url.Action("SomeImage", "Home", new { id = 123 })" />

This actually creates the following, depending on whether you're doing anything special with your routing:

<img src="/Home/SomeImage/123" />
or possibly
<img src="/Home/SomeImage?id=123" />

Answer 2

I dont see you actually filling your byteArray with data anywhere!

Also, why do you create the byteArray variable in the first place? you already have the blob data as a byte[] in the input variable imagebytes. Remove byteArray and use imagebytes.

public Image getProduct_Image(byte[] imagebytes)
{
    try
    {
        if(imagebytes == null || imagebytes.Length == 0)
            throw new InvalidDataException("The blob does not contain any data");  

        MemoryStream ms = new MemoryStream(imagebytes);
        ms.Position = 0;
        ms.Read((imagebytes, 0, imagebytes.Length);
        ms.ToArray();
        ms.Seek(0, SeekOrigin.Begin);

        System.Drawing.Image returnImage = Image.FromStream((Stream) ms);
        return new Bitmap(returnImage);
    }
    catch(Exception ex)
    {
        // deal with the exception
    }
}