paypal沙盒测试notify_url不能返回问题

付款成功了，但设置了notify_url，我的程序却没有动静，求教大神！
我的notify_url=http://192.122.2.8:8080/paypalipn/ipn.jsp，

我的程序：

il = request.getParameter("receiver_email");
String payerEmail = request.getParameter("payer_email");

//check notification validation
if(res.equals("VERIFIED")) {
// check that paymentStatus=Completed
// check that txnId has not been previously processed
// check that receiverEmail is your Primary PayPal email
// check that paymentAmount/paymentCurrency are correct
// process payment
}
else if(res.equals("INVALID")) {
// log for investigation
}
else {
// error
}
%>
</body>
</html>