spring 获取bean的几种方法

spring 获取bean的几种方法

1. 实现BeanFactoryAware

   public class ServiceLocator implements BeanFactoryAware {

       private static BeanFactory beanFactory;
   
       @Override
       public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
           ServiceLocator.beanFactory = beanFactory;
       }
   
       /**
        * 根据提供的bean名称得到相应的服务类
        * 
        * @param servName
        * bean名称
        */
       public static Object getService(String servName) {
           return beanFactory.getBean(servName);
       }
   
   }
   

   spring配置文件

   <bean id="serviceLocator" class="com.taobao.appcenter.common.ServiceLocator" lazy-init="false"/>
   

2. 实现ApplicationContextAware

   public class SpringContextsUtil implements ApplicationContextAware {
   
       private static ApplicationContext applicationContext;    //Spring context   
   
       @Override
       public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
           SpringContextsUtil.applicationContext = applicationContext;
       }
   
       /**
         * @return ApplicationContext
         */
         public static ApplicationContext getApplicationContext() {
           return applicationContext;
         }
   
         /**
         * 获取对象  
         * @param name
         * @return Object 一个以所给名字注册的bean的实例
         * @throws BeansException
         */
         public static Object getBean(String name) throws BeansException {
           return applicationContext.getBean(name);
         }
   }
   

   spring xml配置文件

   <bean id="springContext" class="com.taobao.appcenter.common.SpringContext" lazy-init="false"/>
   

3. 通过servlet 或listener设置spring的ApplicationContext,以便后来引用,这个是针对web 工程的

       public class SpringContext {
       private static ApplicationContext applicationContext; // Spring应用上下文环境
   
       public static void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
           SpringContext.applicationContext = applicationContext;
       }
   
       /**
        * @return ApplicationContext
        */
       public static ApplicationContext getApplicationContext() {
           return applicationContext;
       }
   
       public static Object getBean(String name) throws BeansException {
           return applicationContext.getBean(name);
       }
   }
   

   上面的SpingContext谁没实现任何接口的，不是回调的方式。而是在listener或者servlet中set进来

   public class SpringContextLoaderListener extends ContextLoaderListener {
   
   
       public void contextInitialized(ServletContextEvent event){
           super.contextInitialized(event);
           SpringContext.setApplicationContext(WebApplicationContextUtils.getWebApplicationContext(event.getServletContext()));
       }
   
   
   }
   

   替换web.xml文件的listener为上面的文件

   <listener>
       <listener-class>com.taobao.appcenter.common.SpringContextLoaderListener</listener-class>
   </listener>
   

   servlet的代码如下

   public class SpringContextLoaderServlet extends ContextLoaderServlet {
    private ContextLoader contextLoader;
       public void init() throws ServletException {
           this.contextLoader = createContextLoader();
           SpringContext.setApplicationContext(this.contextLoader.initWebApplicationContext(getServletContext()));
       }
   }
   

   然后配置web.xml中的servlt和mapping即可。

4. 调用

   由于使用的都是静态函数,使用getBean(Stirng name)或者getService(String serviceName)就可以获得xml配置的业务自己bean。