Francois Degrelle's blog
One of my recent assignments was to build a web page that needed to show images that are stored in a database.
Having a strong PLSQL coding background the solution seemed to be close to my fingertips and I created a PLSQL function that I called through the PLSQL Gateway.
| CREATE TABLE PHOTOS ( IMAGEID NUMBER(10), IMAGE BLOB ) / |
|
CREATE OR REPLACE PROCEDURE Display_Image(p_id NUMBER) IS -- Get the blob image owa_util.mime_header('images/gif'); END; |
The web page could be called with the following URL and did what I was asked to do
| img src="http://machine:port/pls/myapp/display_image?p_id=12" width="115" border="0" |
This works like a charm but has a caveat that I discovered when presenting it to the network department. The network department didn’t like the idea of exposing the database server to the Internet, which indeed is considerably unsafe.
Back to the whiteboard, I thought of using Web Service. This approach just didn’t feel right and appeared to be too complex for this little solution to build. Eventually I decided to write a JavaServer Page to do the job.
The Java class to stream the image from the database column
package image; import java.sql.*; public class images String req = "" ; }
import java.io.*;
import java.util.*;
import oracle.jdbc.*;
import oracle.sql.*;
{
/*-------------------------
* Get the Blob image
*------------------------*/
public static byte[] getPhoto (OracleConnection conn, int iNumPhoto)
throws Exception, SQLException
{
Blob img ;
byte[] imgData = null ;
Statement stmt = conn.createStatement ();
// Query
req = "Select image From IMAGES Where ImageID = " + iNumPhoto ;
ResultSet rset = stmt.executeQuery ( req );
while (rset.next ())
{
img = rset.getBlob(1);
imgData = img.getBytes(1,(int)img.length());
}
rset.close();
stmt.close();
return imgData ;
}
The JavaServer Page includes the bean so its methods can be accessed in the JSP page using scriplets and “photo” as a named bean reference
<%@ page import = "image.*" %>
<%@ page import = "java.io.*" %>
<%@ page import = "oracle.jdbc.OracleConnection" %>
<jsp:useBean id="photo" class="image.images" scope="session" />
<%
int iNumPhoto ;
oracle.jdbc.driver.OracleConnection conn = null;
if ( request.getParameter("imgID") != null )
{
iNumPhoto = Integer.parseInt(request.getParameter("imgID")) ;
try
{
conn = …………;
conn.setAutoCommit (false);
// get the image from the database
byte[] imgData = photo.getPhoto( conn, iNumPhoto ) ;
// display the image
response.setContentType("image/gif");
OutputStream o = response.getOutputStream();
o.write(imgData);
o.flush();
o.close();
}
catch (Exception e)
{
e.printStackTrace();
throw e;
}
finally
{
… Close the connexion … ;
}
}
%>
To display the image on the web, I now use the following image URL
| img src="image.jsp?imgID=12" width="115" border="0" |
Special thank you to Frank Nimphius for its good suggestions on the style ;o)
Francois
