单项选择题 A developer is designing a web application which extensively uses EJBs and JMS.  The developer finds that there is a lot of duplicated code to build the JNDI contexts to access the beans and queues. Further， because of the complexity， there are numerous errors in the code.  Which J2EE design pattern provides a solution for this problem？（）

多项选择题 Whichthe twoarecharacteristicsoftheServiceLocatorpattern？（）

单项选择题 Assumethetaghandlerforast：simpletagextendsSimpleTagSupport.Inwhatwaycanscriptletcodebeusedinthebodyofst：simple？（）