Spring工具类:WebApplicationContextUtils
当 Web 应用集成 Spring 容器后,代表 Spring 容器的WebApplicationContext对象将以
WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE 为键存放在ServletContext的属性列表中。您当然可以直接通过以下语句获取 WebApplicationContext:
1 | WebApplicationContext wac = (WebApplicationContext)servletContext.getAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE); |
但通过位于 org.springframework.web.context.support 包中的WebApplicationContextUtils 工具类获取 WebApplicationContext 更方便:
1 2 3 4 | ApplicationContext ac1 =WebApplicationContextUtils.getRequiredWebApplicationContext(ServletContext sc); ApplicationContext ac2 =WebApplicationContextUtils.getWebApplicationContext(ServletContext sc); ac1.getBean("beanId"); ac2.getBean("beanId"); |
说明:
这种方式适合于采用Spring框架的B/S系统,通过ServletContext对象获取ApplicationContext对象,然后在通过它获取需要的类实例。
上面两个工具方式的区别是,前者在获取失败时抛出异常,后者返回null。
servletContext sc 换成
1.servlet.getServletContext()
2.this.getServletContext()
3.request.getSession().getServletContext();
实例:
1 2 3 4 5 6 7 8 9 10 11 12 | public class demoServlet extends HttpServlet { IDemoWS demoWS; public void init() throws ServletException { super .init(); ServletContext servletContext = this .getServletContext(); WebApplicationContext ctx =WebApplicationContextUtils.getWebApplicationContext(servletContext); demoWS = (ISignpicWS)ctx.getBean( "demoWS" ); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { ..... //request.getSession().getServletContext() } } |