说明：  EJB 最佳实践：改进远程对象设计 Ejb最佳实战，避免臃肿无效的设计，充分发挥EJB的优势。J2EE分布式设计教材。 diamondsong提供
(EJB best practices : Improved Remote Object Design Ejb real best to avoid bloated void in the design, EJB into full play the advantages. Distributed J2EE design materials. For diamondsong)