How to show byte[] as image in jsp page?

[Annahita Moshiri]

Hello mates!

I have successfully stored some images in my db, and now I want to show them in my jsp page using struts.
Here's what I have done:

First I read the images from db and store them in an ArrayList, called allPictures:

           try{
               ArrayList allPictures = new ArrayList();
               con = DB.getConnection();
               st = con.createStatement();
               query = "SELECT specimanPictureData FROM specimanPictures WHERE specimanNo='" + specimanNo + "'";
               rs = st.executeQuery(query);
               byte[] imageData = null;
               while(rs.next()){
                   java.sql.Blob imageBlob = rs.getBlob("specimanPictureData");
                   imageData = imageBlob.getBytes(1, (int)imageBlob.length());
                   allPictures.add(imageData);
               }//end while
           }//end try

Then in my Action, all I do is:

        ArrayList specimanPictures = getSpecimanPictures(pictureNo);
        session.setAttribute("specimanPictures", specimanPictures);

now that I have my arraylist of byte[]s , I want to show them in my page (which contains other information about my speciman, besides it's pictures):

                <logic:iterate id="picture" name="specimanPictures">
                    ?<br>
                </logic:iterate>

I don't know what should I put instead of "?". How can I use <html:img> tag here? :roll:
Thanks in advance!

[Jeanne Boyarsky]

Annahita,
Your Struts action needs to write these images to somewhere on the server. Then the loop can point to that location.

Browsers require images to be separate files. As a result, you can't just write out the images inline.

[Merrill Higginson]

Another possibility would be to create an action that gets a single image from the database by specimen Number and writes it to the outputStream of the HttpServletResponse object with the header set to the proper MIME type. Or even easier: extend the org.apache.struts.actions.DownloadAction class provided by Struts.

Then within the loop in your JSP, use the html:img tag to call the action and display the image.

Example:

<logic:iterate id="specimen" name="Specimens">  
        <html:img action="myImageAction" paramId="SpecimenNo"  paramName="specimen" paramProperty="number" />
</logic:iterate>   

[Annahita Moshiri]

Thanks a lot for your replies!

Merril:
When I try to add the action part to <html:img> tag:

<html:img action="myImageAction"     

I get this error in compile:

Attribute action invalid for tag img acording to TLD    

I use struts 2 by the way. How can I fix this?! (as you can see I'm a greenhorn!)

Jeanne:
If I want to choose this approach, how can I take care of deleting those images from the file system afterward? I think after some queries there will be many images left uncared in the file system. How can I deal with them? If I can trust the users to always click "logout", I think I can take care of deleting those temporary images, but what if they just close their browser without logging out?

[Jeanne Boyarsky]

Annahita,
I think Merril meant 'src".

As for the cleanup, you can create a session listener to detect when a session invalidates itself. this will trigger on explicit logout and session timeout.

[Merrill Higginson]

If you were using Struts 2, you would not be using a <logic:iterate> tag. You must be using some version of Struts 1. The latest version of Struts 1 (1.3.10) does allow an action attribute for the html:img tag. However, if you're using a version that doesn't allow it, just use page="myImageAction.do".