Task 1
Two query strings are required: one to select all distinct colors in the table and the other for Blob selection in a prepared statement. Here are the SQL statements needed:
for sQueryD
SELECT DISTINCT TColor
FROM TeeColor
for sQueryP
SELECT TCBlob
FROM TeeColor
WHERE TColor = ?
Your job is to set up Strings with the appropriate SQL statements.
sQueryD =
"SELECT DISTINCT TColor " +
"FROM TeeColor",
sQueryP =
"SELECT TCBlob " +
"FROM TeeColor " +
"WHERE TColor = ?",
|
Task 2
In doConnect(), after connecting and creating a Statement, execute the DISTINCT query, retrieve the rows and load the color names into a combo box.
rs = stmt.executeQuery( sQueryD );
while( rs.next() )
{
jcb.addItem( rs.getString( 1 ) );
}
|
Task 3
Now that the program is connected, after closing the Statement and doing some screen setup, it is time to execute prepareStatement. This is still in doConnect().
pstmt = con.prepareStatement( sQueryP );
Task 4
In doRetrieve(), set the String and excute the PreparedStatement query; Get the Blob and its length; Materialize the Blob data using Blob.getBytes() and use the resulting aray of bytes to create an ImageIcon with ImageIcon( byte[] ). ( Note that in Blob.getBytes(), the binary data starts at 1. ) Use JLabel.setIcon() to load the image to the JLabel.
pstmt.setString( 1,
(String)(jcb.getSelectedItem()) );
rs = pstmt.executeQuery();
if( rs.next() )
{
blob = rs.getBlob( 1 );
iLength = (int)(blob.length());
ii = new ImageIcon(
blob.getBytes( 1, iLength )
);
jlImage.setIcon( ii );
|
Task 5
In EndApp(), insert code to close the connection.
if( con != null)
{
try { con.close(); }
catch( Exception e ) {}
}
|
Print-friendly Version
