发布网友 发布时间:2022-11-13 13:38
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热心网友 时间:2024-10-01 04:23
方法一:在初始化时保存ApplicationContext对象代码:ApplicationContextac=newFileSystemXmlApplicationContext("applicationContext.xml");ac.getBean("beanId");说明:这种方式适用于采用Spring框架的独立应用程序,需要程序通过配置文件手工初始化Spring的情况。方法二:通过Spring提供的工具类获取ApplicationContext对象代码:importorg.springframework.web.context.support.WebApplicationContextUtils;ApplicationContextac1=WebApplicationContextUtils.getRequiredWebApplicationContext(ServletContextsc);ApplicationContextac2=WebApplicationContextUtils.getWebApplicationContext(ServletContextsc);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。其中servletContextsc可以具体换成servlet.getServletContext()或者this.getServletContext()或者request.getSession().getServletContext();另外,由于spring是注入的对象放在ServletContext中的,所以可以直接在ServletContext取出WebApplicationContext对象:WebApplicationContextwebApplicationContext=(WebApplicationContext)servletContext.getAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE);方法三:继承自抽象类ApplicationObjectSupport说明:抽象类ApplicationObjectSupport提供getApplicationContext()方法,可以方便的获取到ApplicationContext。Spring初始化时,会通过该抽象类的setApplicationContext(ApplicationContextcontext)方法将ApplicationContext对象注入。方法四:继承自抽象类WebApplicationObjectSupport说明:类似上面方法,调用getWebApplicationContext()获取WebApplicationContext方法五:实现接口ApplicationContextAware说明:实现该接口的setApplicationContext(ApplicationContextcontext)方法,并保存ApplicationContext对象。Spring初始化时,会通过该方法将ApplicationContext对象注入。在web应用中一般用ContextLoaderListener加载webapplication,如果需要在action之外或者control类之外获取webapplication思路之一是,单独写个类放在static变量中,类似于:publicclassAppContext{privatestaticAppContextinstance;privateAbstractApplicationContextappContext;publicsynchronizedstaticAppContextgetInstance(){if(instance==null){instance=newAppContext();}returninstance;}privateAppContext(){this.appContext=newClassPathXmlApplicationContext("/applicationContext.xml");}publicAbstractApplicationContextgetAppContext(){returnappContext;}}不过这样,还是加载了2次applicationcontext,servlet一次,路径加载一次;觉得不如直接用路径加载,舍掉servlet加载在网上也找了些其他说法:实现ApplicationContextAware,,,接口,或者servletcontextAware接口,还要写配置文件。有的竟然要把配置文件里的listener,换成自己的类,这样纯粹多此一举。不过有的应用不是替换,是在补一个listener,我在一版的jpetstore(具体那一版不知道)里发现了这个:[web.xml]里org.springframework.web.context.ContextLoaderListenercom.ibatis.jpetstore.util.SpringInit其中SpringInit实现接口ServletContextListener:packagecom.ibatis.jpetstore.util;importjavax.servlet.ServletContextEvent;importjavax.servlet.ServletContextListener;importorg.springframework.context.ApplicationContext;importorg.springframework.web.context.WebApplicationContext;importorg.springframework.web.context.support.WebApplicationContextUtils;publicclassSpringInitimplementsServletContextListener{privatestaticWebApplicationContextspringContext;publicSpringInit(){super();}publicvoidcontextInitialized(ServletContextEventevent){springContext=WebApplicationContextUtils.getWebApplicationContext(event.getServletContext());}publicvoidcontextDestroyed(ServletContextEventevent){}publicstaticApplicationContextgetApplicationContext(){returnspringContext;}}在其中的一个bean的构造里SpringInit获取applicationcontext,代码:publicOrderBean(){this((AccountService)SpringInit.getApplicationContext().getBean("accountService"),(OrderService)SpringInit.getApplicationContext().getBean("orderService"));}