How to display a BLOB in java

04-30-2005, 08:23 AM

gertcuppens

Member

Join Date: Feb 2005

Location: ANtwerp - Belgium

Posts: 34

How to display a BLOB in java

In my database I have a table containing a blob. This blob is the poster of a corresponding film. To display a blob inside a JSP, you have to refer to a servlet, like this :

Code:

<td width="200" rowspan="6"><div align="center"><img src="/gco/cluifimg?nocache=<%=new java.util.Date()%>" width="150" height="200"></div></td>

The parameter after /gco/cluifimg is only necessary to prevent the first blob shown to be left in the cache. Without this parameter, I only showed the poster of the first film, and after that the cache showed always this first poster with whatever movie was selected.

The /gco/cluifimg is inside the web.xml to let Tomcat know that the servlet to show the blob is called imageServlet.
ANd here's the code for this servlet.

Code:

/*
 * Deze servlet dient om gegevens uit een BLOB terug om te zetten
 * in een JPG of GIF. Eerste toepassing hiervoor is het afbeelden
 * van de posters die in de CLUIF-databank zitten
 */
package org.gertcuppens.controller;

import javax.servlet.http.HttpServlet; 
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession; 
import javax.servlet.ServletException;

import java.io.OutputStream; 
import java.io.IOException;

import java.sql.Blob; 
import java.sql.SQLException; 

import org.apache.log4j.Logger;

//import org.gertcuppens.algemeen.Melding; 
import org.gertcuppens.cluif.Film;



/**
 * @author GC1494
 *
 * 
 */
public class ImageServlet extends HttpServlet {

	public void service(HttpServletRequest _request, HttpServletResponse _response) 
	throws ServletException, IOException   
	{
		
		byte[] blobBytesArray = null;
		OutputStream stream = _response.getOutputStream(); 
		System.out.println("in imageservlet");
		Logger gcoLogger = Logger.getLogger("gco.log");		
		gcoLogger.debug("in imageServlet "); 
		HttpSession sessie = _request.getSession(false);
		if (sessie != null)
		{
			System.out.println("sessie opgehaald");
			Film film = (Film) sessie.getAttribute("film");
			if (film != null)
			{
				System.out.println("film opgehaald"); 
				gcoLogger.debug("imageservlet - filmnummer " + film.getFilmnummer());
				
				try {
				
					Blob poster = film.getPoster(); 
					if (poster != null)
						{
							int len = new Integer( new Long( poster.length()).toString() ).intValue();
							blobBytesArray = poster.getBytes(1,len);
							if (blobBytesArray != null)
							{
								gcoLogger.debug("imageservlet - blob <> null ");  
								if (blobBytesArray.length > 0 )
								{
								gcoLogger.debug("imageservlet - blob.length > 0 ");  	
								stream.write(blobBytesArray);
								}
	                	
							} /* blobBytesArray != null */
						} /* poster != null */ 
					} catch (SQLException sqlEx)
						{
						// Melding melding = new Melding(sqlEx);
						System.out.println("sqlEx bij blob"); 
						gcoLogger.debug("sqlEx bij blob"); 
						
						}
					catch (IOException ioEx)
					{
					// Melding melding = new Melding(sqlEx);
					System.out.println("ioEx bij blob"); 
					gcoLogger.debug("ioEx bij blob"); 
					
					}
									
			} /* film != null */
			
		} /* (sessie != null) */ 
		
		
	} /* public void service() */ 
} /* public class ImageServlet */

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