获取Spring上下文

ApplicationContext ctx = WebApplicationContextUtils.getWebApplicationContext(ServletActionContext.getServletContext());   
//获取所有Spring中的所有bean   
String [] names = ctx.getBeanDefinitionNames();   
for(int i=0;i<names.length;i++){   
    System.out.println("上下文实例："+names[i]);   
}   
//根据名称获取单个bean   
LoginAction action=(LoginAction)ctx.getBean("action");

ApplicationContext ctx = WebApplicationContextUtils.getRequiredWebApplicationContext(request.getSession().getServletContext());