For those who is looking for J2EE PayPal Checkout solutions, we would like to offer our product - PayPal Checkout (with IPN): http://www.softwarebasic.com/
Free download: http://www.softwarebasic.com/products.html#demo
Encapsulates PayPal website payment processing into a single back end component . This easy-to-use component enables J2EE developers to seamlessly integrate their own shopping cart instead of the standard PayPal shopping cart with PayPal Payment processing in minutes!
PayPal Checkout IPN
Includes all PayPal Checkout features plus Instant Payment Notification (IPN) handling. This easy-to-use component enables J2EE developers to add IPN listeners to every checkout. When PalPal send back confirmation of payment, listeners will be notified. It follows Java 2 standard event model
Software Basic http://www.softwarebasic.com/