I want to display blobs from a database into a JTable column. My code is the following:

public JTable getTable(String table,String query)throws Exception{ JTable t1 = new JTable(); DefaultTableModel dm = new DefaultTableModel(); Statement st = con.createStatement(); ResultSet rs = st.executeQuery(query); ResultSetMetaData rsmd = rs.getMetaData(); int cols = rsmd.getColumnCount(); String c[] = new String[cols]; for(int i=0;i<cols;i++){ c[i]=rsmd.getColumnName(i+1); dm.addColumn(c[i]); } //get data from rows Object row[]=new Object[cols]; while(rs.next()){ row[0] = rs.getString(1); row[1] = rs.getString(2); row[2] = rs.getString(3); row[3] = rs.getString(4); row[4] = rs.getString(5); row[5] = rs.getString(6); java.sql.Blob blob = rs.getBlob(7); int blobLength = (int) blob.length(); byte[] blobAsBytes = blob.getBytes(1, blobLength); ImageIcon picture = new ImageIcon(blobAsBytes); row[6] = picture; row[7] = rs.getString(8); row[8] = rs.getString(9); dm.addRow(row); } t1.setModel(dm); con.close(); return t1;
}

When I run this code the JTable dispays: javax.swing.ImageIcon@*numbers* instead of the image itself.

2 Answers

The DefaultTableModel displays any object as a String by calling its toString() method.

If you want to change that you have to tell the DefaultTableModel what the column's content is by overriding the getColumnClass() method.

 DefaultTableModel dm = new DefaultTableModel(){ public class<?> getColumnClass(int columnIndex){ return 6==columnIndex?ImageIcon.class, String.class; } };

But there is a chance that JTable does not have a DefaultRenderer for ImageIcon and still displays something unexpected. In that case you also have to set a DefaultRenderer for class ImageIcon yourself.

JTable Cell Renderer

You can add a renderer that displays an icon. Such a renderer would look like this:

public class IconCellRenderer extends DefaultTableCellRenderer { @Override public Component getTableCellRendererComponent( JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column ) { Component c = super.getTableCellRendererComponent( table, value, isSelected, hasFocus, row, column ); ((JLabel) c).setIcon( (ImageIcon) value ); ((JLabel) c).setText( "" ); return c; }
}

You can add this renderer several ways:

1. Register a renderer for the ImageIcon class:

   table.setDefaultRenderer( ImageIcon.class, new IconCellRenderer( ) );

2. Specify a renderer for a column:

   int imageViewIndex = table.convertColumnIndexToView( 6 ); // view index of ImageIcon data
   table.getColumnModel( ).getColumn( imageViewIndex ).setRenderer( new IconCellRenderer( ) );

3. Subclass JTable and override getCellRenderer:

   final int imageModelIndex = 6; // model index of ImageIcon data
   JTable table = new JTable( ) { TableCellRenderer imageIconRenderer = new IconCellRenderer( ); @Override public TableCellRenderer getCellRenderer( int row, int column ) { if( convertColumnIndexToModel( column ) == imageModelIndex ) return imageIconRenderer; else return super.getCellRenderer( row, column ); }
   };

Your Answer

Sign up or log in

Sign up using Google Sign up using Facebook Sign up using Email and Password Submit

Post as a guest

Post Your Answer Discard

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy