View stored blob image in the UI using java

[ruba sampath]

Hi,

I am storing an image or pdf in the database as blob type.

Now i need to disply the image in the UI.

How to disply the image in the UI screen using java code?

Kindly guide us to proceed further.

Thank you.

[Rob Spoor]

For images it's quite easy. Use ImageIO to convert the binary data into a BufferedImage, then use ImageIcon and JLabel for displaying it.
For PDF files it's harder, but I believe PDF renderer can help you out.

[ruba sampath]

Thank you. But i am not using swing or applet in my application. Is it possible to display through ServletOutputStream?

[Rob Spoor]

Sure. You need a separate servlet that will a) set the right content type, b) if possible, set the content size, and c) include only the image / PDF file data and no other data (like leading / trailing whitespace). The latter makes JSP pages not very good for binary data like images or PDF files, as it's really easy to accidentally add leading whitespace. If you decide to use a JSP page, make sure that there are no line breaks whatsoever outside of the JSP tags - not even between directives.

[ruba sampath]

Thank you very much. Its working now. But how to restrict only upload images and pdf and not other types.

[Rob Spoor]

I believe that in HTML5 you can specify file extensions to filter on, but in HTML4 and before you can only refuse to process the files in the form's action page (servlet / JSP / PHP / ...).