用Java EE 5实现的网上书店实例

SELECT MAX(BOOK.PURCHASE_ORDER.ORDER_NUM)+1 

  AS MAXORDERID FROM BOOK.PURCHASE_ORDER

     private PurchaseOrderFacadeLocal lookupPurchaseOrderFacade() ...{
try ...{
Context c = new InitialContext();
return (PurchaseOrderFacadeLocal) c.lookup

              ("java:comp/env/ejb/PurchaseOrderFacade");
}
catch(NamingException ne) ...{
Logger.getLogger(getClass().getName()).log(Level.SEVERE,"exception caught" ,ne);
throw new RuntimeException(ne);
}
}

    @EJB PurchaseOrderFacadeLocal ejbOrderLocal;
public String buttonAddOrder_action() ...{
// 待做事项：处理操作。返回的值是一个导航
// 如果名称为 null，则返回到同一页。
CachedRowSetDataProvider maxOrder = getSessionBean1().getMaxOrderDataProvider();
maxOrder.refresh();
PurchaseOrder order = new PurchaseOrder();
order.setOrderNum((Integer) maxOrder.getValue("MAXORDERID"));
order.setCustomerId((String)dropDown1.getValue());
order.setProductId((Integer)staticText1.getValue());
order.setQuantity(new Short((String)textField1.getValue()));
ejbOrderLocal.create(order);
getRequestBean1().setCustomerId((String)dropDown1.getValue());

return "case1";
}