Displaying an Oracle BLOB image.

[achana chan]

Hi.
I believe I have successfully created a "serialized" record e.g. empRecord.class
It holds the data retrieved from an Oracle table.
However I have this problem of trying to get at the BLOB field in empRecord.class from the Applet.
Getting at "serialized" text or numeric fields seem to be quite easy in comparison !
Also I hope I am using the right terminology when I say "serialized" e.g.

import oracle.sql.*;
import java.io.Serializable;
public class emp implements Serializable
{
  public int empNo;
  public String empName;
  public BLOB empPicture;
}

I think I know how to connect to the database , create input/output streams and get at an image, but from the Applet, how exactly do I get at this Oracle BLOB in the serialized record ?
Is it possible to create a "window" (java.awt.window) and display the image in it ?

How does one get the "serialized" image into the window ?
Sometimes I despair with JAVA, after nearly 5 months of coding, I am still floundering. Also this proliferation of terminology and packages and tools is very confusing and unhelpful.
It would be nice to know how many of you out there remembers all the classes and methods and whatnot.
[ October 31, 2002: Message edited by: achana chan ]

[Michael Zalewski]

You don't give very specific information. But your problem might be trying to serialize a BLOB. Serialize the byte[] from the BLOB instead. A Blob object is only useful while you are connected to the database, and the database connection probably doesn't travel with whatever the heck it is you are serializing to.
Replace

public BLOB /* sb Blob */ empPicture;

with

public byte[] empPicture;

[achana chan]

Hi Michael.
Thanks for the tip.
If I change BLOB to byte[], I have several errors:
On the server side, neither the text data nor the blob is retrieved from the database .
On the client side, the JAVA console throws these distressing errors :
BaseTunnelClient : content-length is 91
BaseTunnelClient : connecting... JSESSIONID=B0959584F5E504ED7B02454C9A277907
java.io.IOException: Server returned HTTP response code: 500 for URL: http://192.168.1.3/saysit/RemotedemoServer
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
at sun.plugin.net.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.getHeaderFields(Unknown Source)
at sun.plugin.net.protocol.http.HttpURLConnection.checkCookieHeader(Unknown Source)
at sun.plugin.net.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
at com.developer.Tunnel.client.BaseTunnelClient._invokeMethod(BaseTunnelClient.java:194)
at com.developer.Tunnel.RemotedemoClient.query(RemotedemoClient.java:100)
at com.developer.Tunnel.demoApplet.actionPerformed(demoApplet.java:194)
at java.awt.Button.processActionEvent(Unknown Source)
at java.awt.Button.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
com.developer.Tunnel.client.BaseTunnelClient$TunnelException: Server returned HTTP response code: 500 for URL: http://192.168.1.3/saysit/RemotedemoServer
at com.developer.Tunnel.client.BaseTunnelClient._invokeMethod(BaseTunnelClient.java:217)
at com.developer.Tunnel.RemotedemoClient.query(RemotedemoClient.java:100)
at com.developer.Tunnel.demoApplet.actionPerformed(demoApplet.java:194)
at java.awt.Button.processActionEvent(Unknown Source)
at java.awt.Button.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

[achana chan]

Dear Michael,
This is how I set empRecord.class ie serialize it, I snipped the code because it is a long tedious piece of code :

//
  public empRecord query(int empno)
  {  
    empRecord thisRec = null;
    try
    {  
      prepStmt.setInt(1, empno); // placeholder for "?" in position 1
      ResultSet rset = prepStmt.executeQuery();
      System.out.println("\n<<ORA>>AllEmpTN : executed prepStmt, record : ");
      if (rset.next())
      {
        // Create a new record object...
        thisRec = new empRecord();
        //
        // Set the values...
        thisRec.empno = rset.getInt("empno");
        thisRec.ename = rset.getString("ename");
        thisRec.fname = rset.getString("fname");         
        thisRec.job = rset.getString("job");
        thisRec.mgr = rset.getInt("mgr");
        thisRec.hiredate = rset.getDate("hiredate");
        thisRec.sal = rset.getDouble("sal");
        thisRec.comm = rset.getDouble("comm");
        thisRec.deptno = rset.getInt("deptno");
        [B]BLOB picBLOB = ((OracleResultSet) rset).getBLOB("picture");
        thisRec.picture = picBLOB;[/B]
        //
        System.out.println(thisRec.ename+","+thisRec.fname+","+thisRec.job+","+thisRec.mgr+","+
                           thisRec.hiredate+","+thisRec.sal+","+thisRec.comm+","+thisRec.deptno);
      } 
    } //end of try-block
    catch (SQLException ex)
    // catch(Exception ex)
    { 
      ex.printStackTrace();
      thisRec = null;
    }
    // okay, let's have a look at the record...
    return thisRec;
  } //end of method empQuery();

[Rene Larsen]

You could try read this post: http://www.coderanch.com/t/297456/JDBC/java/Retreiving-image-JDBC
Rene