public ImageViewer(Frame f,
    String url,
    String user,
    String password) throws IOException, ClassNotFoundException, SQLException, FileNotFoundException 
{
    frame = f;
    MenuBar mb = new MenuBar();
    Menu m;
    MenuItem i;
    f.setMenuBar(mb);
    mb.add(m = new Menu("PostgreSQL"));
    m.add(i= new MenuItem("Initialise"));
    i.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
	ImageViewer.this.init();
      }
    });
    m.add(i= new MenuItem("Exit"));
    ActionListener exitListener = new ActionListener() {
      public void actionPerformed(ActionEvent e) {
	ImageViewer.this.close();
      }
    };
    m.addActionListener(exitListener);
    mb.add(m = new Menu("Image"));
    m.add(i= new MenuItem("Import"));
    ActionListener importListener = new ActionListener() {
      public void actionPerformed(ActionEvent e) {
	ImageViewer.this.importImage();
      }
    };
    i.addActionListener(importListener);
    m.add(i= new MenuItem("Remove"));
    ActionListener removeListener = new ActionListener() {
      public void actionPerformed(ActionEvent e) {
	ImageViewer.this.removeImage();
      }
    };
    i.addActionListener(removeListener);
    // To the north is a label used to display the current images name
    f.add("North",label = new Label());
    // We have a panel to the south of the frame containing the controls
    Panel p = new Panel();
    p.setLayout(new FlowLayout());
    Button b;
    p.add(b=new Button("Refresh List"));
    b.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
	ImageViewer.this.refreshList();
      }
    });
    p.add(b=new Button("Import new image"));
    b.addActionListener(importListener);
    p.add(b=new Button("Remove image"));
    b.addActionListener(removeListener);
    p.add(b=new Button("Quit"));
    b.addActionListener(exitListener);
    f.add("South",p);
    // And a panel to the west containing the list of available images
    f.add("West",list=new List());
    list.addItemListener(this);
    // Finally the centre contains our image
    f.add("Center",canvas = new imageCanvas());
    // Load the driver
    Class.forName("org.postgresql.Driver");
    // Connect to database
    db = DriverManager.getConnection(url, user, password);
    // Create a statement
    stat = db.createStatement();
    // Also, get the LargeObjectManager for this connection
    lom = ((org.postgresql.Connection)db).getLargeObjectAPI();
    // Now refresh the image selection list
    refreshList();
}

 public  void close() 
{
    try {
      db.close();
    } catch(SQLException ex) {
      System.err.println(ex.toString());
    }
    System.exit(0);
}

This closes the connection, and ends the application

 public  void displayImage(String name) 
{
    try {
      //
      // Now as we are opening and reading a large object we must
      // turn on Transactions. This includes the ResultSet.getBytes()
      // method when it's used on a field of type oid!
      //
      db.setAutoCommit(false);
      ResultSet rs = stat.executeQuery("select imgoid from images where imgname='"+name+"'");
      if(rs!=null) {
	// Even though there should only be one image, we still have to
	// cycle through the ResultSet
	while(rs.next()) {
	  canvas.setImage(canvas.getToolkit().createImage(rs.getBytes(1)));
	  label.setText(currentImage = name);
	}
      }
      rs.close();
    } catch(SQLException ex) {
      label.setText(ex.toString());
    } finally {
	try {
	  db.setAutoCommit(true);
	} catch(SQLException ex2) {
	}
    }
}

This displays an image from the database. For images, this is the easiest method.

 public  void importImage() 
{
    FileDialog d = new FileDialog(frame,"Import Image",FileDialog.LOAD);
    d.setVisible(true);
    String name = d.getFile();
    String dir = d.getDirectory();
    d.dispose();
    // now start the true importer
    Thread t = new importer(db,name,dir);
    //t.setPriority(Thread.MAX_PRIORITY);
    t.start();
}

This imports an image into the database, using a Thread to do this in the background.

 public  void init() 
{
    try {
      //db.setAutoCommit(true);
      stat.executeUpdate("create table images (imgname name,imgoid oid)");
      label.setText("Initialised database");
      db.commit();
    } catch(SQLException ex) {
      label.setText(ex.toString());
    }
    // This must run outside the previous try{} catch{} segment
    //try {
    //db.setAutoCommit(true);
    //} catch(SQLException ex) {
    //label.setText(ex.toString());
    //}
}

This method initialises the database by creating a table that contains the image names, and Large Object OID's

 public static  void instructions() 
{
    System.err.println("java example.ImageViewer jdbc-url user password");
    System.err.println("\nExamples:\n");
    System.err.println("java -Djdbc.driver=org.postgresql.Driver example.ImageViewer jdbc:postgresql:test postgres password\n");
    System.err.println("This example tests the binary large object api of the driver.\nBasically, it will allow you to store and view images held in the database.");
    System.err.println("Note: If you are running this for the first time on a particular database,\nyou have to select \"Initialise\" in the \"PostgreSQL\" menu.\nThis will create a table used to store image names.");
}

This is the command line instructions

 public  void itemStateChanged(ItemEvent e) 
{
    displayImage(list.getItem(((Integer)e.getItem()).intValue()));
}

 public static  void main(String[] args) 
{
    if(args.length!=3) {
      instructions();
      System.exit(1);
    }
    try {
      Frame frame = new Frame("PostgreSQL ImageViewer v7.0 rev 1");
      frame.setLayout(new BorderLayout());
      ImageViewer viewer = new ImageViewer(frame,args[0],args[1],args[2]);
      frame.pack();
      frame.setLocation(0,50);
      frame.setVisible(true);
    } catch(Exception ex) {
      System.err.println("Exception caught.\n"+ex);
      ex.printStackTrace();
    }
}

This is the application entry point

 public  void refreshList() 
{
    try {
      // First, we'll run a query, retrieving all of the image names
      ResultSet rs = stat.executeQuery("select imgname from images order by imgname");
      if(rs!=null) {
	list.removeAll();
	while(rs.next())
	  list.addItem(rs.getString(1));
	rs.close();
      }
    } catch(SQLException ex) {
      label.setText(ex.toString()+" Have you initialised the database?");
    }
}

This refreshes the list of available images

 public  void removeImage() 
{
    try {
      //
      // Delete any large objects for the current name
      //
      // Note: We don't need to worry about being in a transaction
      // here, because we are not opening any blobs, only deleting
      // them
      //
      ResultSet rs = stat.executeQuery("select imgoid from images where imgname='"+currentImage+"'");
      if(rs!=null) {
	// Even though there should only be one image, we still have to
	// cycle through the ResultSet
	while(rs.next()) {
	  lom.delete(rs.getInt(1));
	}
      }
      rs.close();
      // Finally delete any entries for that name
      stat.executeUpdate("delete from images where imgname='"+currentImage+"'");
      label.setText(currentImage+" deleted");
      currentImage=null;
      refreshList();
    } catch(SQLException ex) {
      label.setText(ex.toString());
    }
}

This removes an image from the database Note: With postgresql, this is the only way of deleting a large object using Java.