Portlet Session
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actionRequest.getPortletSession().setAttribute("id",id,PortletSession.APPLICATION_SCOPE);
(String)renderRequest.getPortletSession().getAttribute("id",PortletSession.APPLICATION_SCOPE);
PORTLET_SCOPE :只能在同一个portlet中使用
APPLICATION_SCOPE:可以在所有Porlet中使用,也能在Servlet/JSP等