You can use the AttachmentHandler interface to manage an attachment to an email message that appears in the message list on the BlackBerry® device.

1. Import the required classes and interfaces.

   import net.rim.blackberry.api.mail.*;
   import net.rim.device.api.ui.container.*;
   import net.rim.device.api.ui.component.*;

2. Implement the AttachmentHandler interface to create a custom attachment handler.

   public class AttachTest implements AttachmentHandler {...}

3. Implement the supports(String) method, to specify the content type of the attachment supported by your handler.

   public boolean supports(String contentType)
   {
      return (contentType.toLowerCase().indexOf("contenttype") != -1 ? true : false);
   }

4. Implement the menuString() method, to specify the text of the menu item that displays when a user selects an attachment.

   public String menuString()
   {
      return "Custom Attachment Viewer";
   }

5. Implement the run() method to specify what should happen when a user clicks the menu item. In the following code sample, a new screen uses the RichTextField class to display a String representation of the content of the attachment.

   public void run(Message m, SupportedAttachmentPart p)
   {
      MainScreen view = new MainScreen();
      view.setTitle("Attachment Viewer");
      view.add(new RichTextField(new String((byte[])p.getContent())));
   }

6. Invoke AttachmentHandlerManager.addAttachmentHandler(), to register the attachment handler with the manager. Note that the attachment name must be prefixed with "x-rimdevice" for the attachment to be sent and stored on the BlackBerry device.

   AttachmentHandlerManager m = AttachmentHandlerManager.getInstance();
   CustomAttachmentHandler ah = new CustomAttachmentHandler();
   m.addAttachmentHandler(ah);