Bug 199021 Error message pops up several times when click an invalid dataset
Description: There is a sqlserver datasource and dataset, remove the jtds driver to let the dataset invalid. Double click on the dataset, the error message will pop up serveral times. Build version:2.2.0.v20070807-0630 Steps to reproduce: 1. Create a sqlserver datasource and dataset. 2. Remove the jtds driver, and the dataset will be invalid. 3. Double click on the dataset. Expect result: Error message pops up once to indicate the problem. Actual result: Error message pops up serveral times.
data/org.eclipse.birt.report.data.oda.jdbc.ui/src/org/eclipse/birt/report/data/oda/jdbc/ui/provider/JdbcMetaDataProvider.java
ExceptionHandler.showException( PlatformUI.getWorkbench( )
						.getDisplay( )
						.getActiveShell( ),
						JdbcPlugin.getResourceString( "exceptionHandler.title.error" ),
						e.getLocalizedMessage( ),
						e );
				return null;
			}
			
		}
		return jdbcConnection;
	}
	
	/*
	 *  (non-Javadoc)
	 * @see org.eclipse.birt.report.data.oda.jdbc.ui.provider.IMetadataProvider#connect(org.eclipse.birt.report.model.api.DataSourceHandle)
	 */
	public Connection connect(DataSourceDesign dataSourceHandle)
	{		
		
		DataSourceDesign handle = (DataSourceDesign) dataSourceHandle;
	
		String userName = (String) handle.getPublicProperties( )
				.findProperty( Constants.ODAUser )
				.getValue( );
		String passWord = (String) handle.getPublicProperties( )
				.findProperty( Constants.ODAPassword )
				.getValue( );
		String url = (String) handle.getPublicProperties( )
				.findProperty( Constants.ODAURL )