Java and Electronic Mail - Java - page 722

}

});
jf . pack ();

}

}

Further, the MailComposeBean program is a JavaBean, so it can be used in GUI builders and
even have its fields set within a JSP. It has a main method, which allows it to be used stan-
dalone (primarily for testing).

To let you compose one or more email messages concurrently, messages being composed are
placed in a JDesktopPane , Java's implementation of Multiple-Document Interface (MDI).
Example 17-12 shows how to construct a multiwindow email implementation. Each
MailComposeBean must be wrapped in a JInternalFrame , which is what you need to place
components in the JDesktopPane . This wrapping is handled inside the MailReaderFrame
method, one instance of which is created in the MailClient constructor. The MailReader-
Frame method newSend() creates an instance of MailComposeBean and shows it in the
JDesktopFrame , returning a reference to the MailComposeBean so that the caller can use
methods such as addRecipient() and send() . It also creates a Compose button and places
it below the desktop pane so that you can create a new composition window by clicking the
button.

Example 17-12. MailComposeFrame.java
public public class class MailComposeFrame MailComposeFrame extends extends JPanel {

JDesktopPane dtPane ;
JButton newButton ;
protected protected int int nx , ny ;

/** To be useful here, a MailComposeBean has to be inside
* its own little JInternalFrame.
*/
public public MailComposeBean newSend () {

// Make the JInternalFrame wrapper
JInternalFrame jf = new

new JInternalFrame ();

// Bake the actual Bean
MailComposeBean newBean =
new new MailComposeBean ( this this , "Compose" , 400 , 250 );

// Arrange them on the diagonal.
jf . setLocation ( nx += 10 , ny += 10 );