gsp, image from array byte

Question

I have a JDO class and a helper class Image to store images within a byte array

JDO class:

@PersistenceCapable
class Recipe{

    @PrimaryKey
        @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
        private Long key

        @Persistent
        private String description

        @Persistent(serialized = "true")
        private Image image;
}

Image class:

class Image implements Serializable {

    private byte[] content
    private String filename
    private String mimeType
}

In the gsp page I iterate through the recipes and want to show the images. I could do a controller like this to get the image src.

 def viewImage= {
    //retrieve photo code here
    response.setHeader("Content-disposition", "attachment; filename=${photo.name}")
    response.contentType = photo.fileType //'image/jpeg' will do too
    response.outputStream << photo.file //'myphoto.jpg' will do too
    response.outputStream.flush()
    return;
  }

But this way I have to send the key of the recipe to this controller and load the image again from the datastore. (I already have loaded it actually. But I think I can not send this data to the controller. Can I ?) Is there not a more convenient way to show the image from a byte array in gsp page ?

Looks like duplicate of stackoverflow.com/questions/4502278/… to me. My answer there could help ;) — Victor Sergienko
– Victor Sergienko, Commented Mar 28, 2011 at 8:32
Hi Victor. Thanks for the comment. I didn't saw you suggestion in this issue. But this looks like exactly what I was searching for. Going to try this out when I'm home. Thanks — mjspier
– mjspier, Commented Mar 28, 2011 at 8:42

Stefan Armbruster · Accepted Answer · 2011-03-27 11:16:01Z

1

I have a similar usecase here, a File domain class holding a byte[] and meta information for uploaded files. To download the file, I'm using:

def fileDownload = {
    long id = params.id as long
    def file = File.get(id)
    assert file
    def fileName = URLEncoder.encode(file.name)
    response.addHeader("content-disposition", "attachment;filename=$fileName")
    response.contentType = file.contentType
    response.contentLength = file.data.size()
    response.outputStream << file.data
}

Regarding reloading the file over and over I would not care too much, Hibernate 2nd level caching cares about it. If you still have a good reason for not loading the file in the download request, you might store it into the http session in a previous call. The downside of storing this in the http session:

in case of many concurrent sessions, high memory consumption
you'll see weird exceptions from Hibernate (be sure for that!)
everything stored in the http session must be serializable

answered Mar 27, 2011 at 11:16

Stefan Armbruster

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1 Comment

mjspier Over a year ago

hi thanks for your answer. was hoping for another solution though.

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