import org.springframework.beans.BeansException; import org.springframework.beans.factory.NoSuchBeanDefinitionException; import org.springframework.context.ApplicationContext; import org.springframework.context.ApplicationContextAware; public class ApplicationContextHelper implements ApplicationContextAware { private static ApplicationContext applicationContext; //Spring應用上下文環境 /** * 實現ApplicationContextAware接口的回調方法,設置上下文環境 * @param applicationContext * @throws BeansException */ public void setApplicationContext(ApplicationContext applicationContext) throws BeansException { ApplicationContextHelper.applicationContext = applicationContext; } /** * @return ApplicationContext */ public static ApplicationContext getApplicationContext() { return applicationContext; } /** * 獲取對象 * @param name * @return Object 一個以所給名字註冊的bean的實例 * @throws BeansException */ public static Object getBean(String name) throws BeansException { return applicationContext.getBean(name); } /** * 獲取類型爲requiredType的對象 * 若是bean不能被類型轉換,相應的異常將會被拋出(BeanNotOfRequiredTypeException) * @param name bean註冊名 * @param requiredType 返回對象類型 * @return Object 返回requiredType類型對象 * @throws BeansException */ public static <T> T getBean(String name, Class<T> requiredType) throws BeansException { return applicationContext.getBean(name, requiredType); } /** * 若是BeanFactory包含一個與所給名稱匹配的bean定義,則返回true * @param name * @return boolean */ public static boolean containsBean(String name) { return applicationContext.containsBean(name); } /** * 判斷以給定名字註冊的bean定義是一個singleton仍是一個prototype。 * 若是與給定名字相應的bean定義沒有被找到,將會拋出一個異常(NoSuchBeanDefinitionException) * @param name * @return boolean * @throws NoSuchBeanDefinitionException */ public static boolean isSingleton(String name) throws NoSuchBeanDefinitionException { return applicationContext.isSingleton(name); } /** * @param name * @return Class 註冊對象的類型 * @throws NoSuchBeanDefinitionException */ public static Class<?> getType(String name) throws NoSuchBeanDefinitionException { return applicationContext.getType(name); } /** * 若是給定的bean名字在bean定義中有別名,則返回這些別名 * @param name * @return * @throws NoSuchBeanDefinitionException */ public static String[] getAliases(String name) throws NoSuchBeanDefinitionException { return applicationContext.getAliases(name); } }
<bean id="applicationContext" class="com.iflashbuy.base.common.ApplicationContextHelper"/>
ApplicatinContextHelper繼承了spring的ApplicationContextAware接口,並實現了setApplicatinContext方法spring容器在啓動過程當中會去查找到繼承了applicationContextAware的全部接口,並將applicationContext經過調用setApplicationContext方法傳遞給ApplicationContextHelper。相關spring實現爲 Spring源碼中ApplicationContextAwareProcessor.postProcessBeforeInitialization()方法。java
有圖有真相web
在一個java web項目中ApplicatationContextHelper這個bean能夠配置在spring上下文中,也能夠配置在springmvc上下文中,當配置在springmvc上下文中時候,ApplicationHelper只可以獲取到springmvc上下恩相關的bean,spring上下文同理。spring