Spring在加载后，怎么获取bean且已经是注入好了对象

public void init() throws ServletException {
		super.init();
		wac = (WebApplicationContext)getServletContext().getAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE);
		printConfigMgmt = (IPrintConfigMgmt)wac.getBean("printConfigMgmt");
		tranBillRePrintMgmt = (ITranBillRePrintMgmt) getBean("tranBillRePrintMgmt");
		loginMgmt = (ILoginMgmt) getBean("loginMgmt");
		eleWriteUploadMgmt = (IEleWriteUploadMgmt) getBean("eleWriteUploadMgmt");
		queryTransInfoMgmt = (IQueryTransInfoMgmt) getBean("transInfoQueryMgmt");
		businessLogMgmt = (IBusinessLogMgmt) getBean("businessLogMgmt");
		logger = SimpleLogger.getLogger(BaseServlet.class);
	}	
	
	public Object getBean(String beanName){
		if(wac!=null)
			return wac.getBean(beanName);
		return null;
	}