CODEWITHSUNDEEP
javajspblob
FredHomme
FredHomme

Reputation: 153

How do i convert blob to image displayed in a JSP

I am trying to retrieve images from database. Currently i was able to show :

    `com.mysql.jdbc.Blob@2aba2aba `

in my jsp output. May i know how to convert that into an image?

i have use the below to call out the above

photo[i].getPhotoFileData();

Upvotes: 1

Views: 17389

Answers (3)

abhishek ringsia
abhishek ringsia

Reputation: 2050

first convert blob to input stream to string . then use that String instead of image URL .

Converting blob to String 

        try {
            Blob blob = staticOffer.getImage(); //blob of image from db
            strOut = new StringBuffer();
            String aux;
            BufferedReader br;

            br = new BufferedReader(new InputStreamReader(blob.getBinaryStream()));
            while ((aux=br.readLine())!=null) {
                strOut.append(aux);
            }
            offerPicStr = strOut.toString();

        } catch (Exception e) {
            e.printStackTrace();
        }

Now use that string it html/jsp in following way 

<img src="data:image/jpeg;base64,${offerPicStr}" width="100" height="100"></img>

Upvotes: 0

pafau k.
pafau k.

Reputation: 1687

You're getting a Blob object - not it's contents. If you want to get raw byte data you have to ask the Blob object for it, e.g.:

Blob blob =  photo[i].getPhotoFileData();
byte[] data = blob.getBytes(0, blob.length());

If you want to create an image on the fly, then just call:

BufferedImage img = ImageIO.read(new ByteArrayInputStream(data));

You can then save the image or ... actually I don't know what else. Thing. Stuff. Display it. Print. Limitless possibilities! Just like at zombo.com!

Upvotes: 1

Mike Deck
Mike Deck

Reputation: 18397

This is more of an issue with the way HTML documents work than with your JSP. You need to understand that HTML doesn't embed images directly. Instead, it uses <img> tags to reference images hosted at different URLs.

In order to display an image stored in a database on an HTML page you're going to need a separate servlet that can handle requests for the image. Your JSP should render an HTML document like the following:

<html>
  <head>
  ...
  </head>
  <body>
    ...
    <img src="www.mydomain.com/images/1234.png" />
    ...
  </body>
</html>

Then you would create a separate servlet to handle all the requests to /images which would make a database call and send the raw bytes from the blob it gets back to the response's output stream. Make sure you also set the Content-Type header correctly based on what image encoding you're using.

In order to send the image back to the requester you have one of two options. You can get the blob's bytes as an array and write that to the OutputStream (e.g. out.write(blob.getBytes(0,blob.length());). Or you can use the getBinaryStream() method and then copy bytes from the InputStream to the OutputStream. Here's an example of that:

public static void copy(Blob from, OutputStream to)
    throws IOException {
  byte[] buf = new byte[4096];
  try(InputStream is = from.getBinaryStream()) {
    while (true) {
      int r = is.read(buf);
      if (r == -1) {
        break;
      }
      to.write(buf, 0, r);
    }
  }
}

NB: This code has not been tested or even compiled, it should only be used as a starting point.

Upvotes: 3

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