JDBC Extension Guide

Purpose of the JDBC Extension

The PostPic JDBC extension complements the PostgreSQL driver for easier managing of ‘image’ objects.

It adds a Java class — PGImage — to represent images and an utility class.

Registration

First of all, we need to tell the PostgreSQL driver to map ‘image’ fields to PGImage instances.

Newer versions of the driver support ‘autoregistration’: they do this mapping automatically by reading a properties file bundled in the extension.

Anyway, the utility class PostPic has methods to check whether the registration has been done and to do it manually:

import postpic.PostPic
 ...
PostPic pp = new PostPic(conn);
if(!pp.isRegistered()) { 
	pp.registerManual() 
}

Using PGImage

Whenever your ResultSet contains an image field, you can obtain the corresponding PGImage this way:

PGImage pi = (PGImage) rSet.getObject("column_name");

To get the corresponding java.awt.Image you can do:

Image img = pi.getImage();