SpringContextHolder工具类获取Bean

叁歲伎倆 2022-02-28 23:54 397阅读 0赞

## 源码 ##

package com.sto.rookie.util;
    
    import java.util.Map;
    
    import org.springframework.beans.BeansException;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.ApplicationContextAware;
    
    /** * 以静态变量保存Spring ApplicationContext， 可在任何代码任何处所任何时辰中取出ApplicaitonContext */
    @Service
    @Lazy(false)
    public class SpringContextHolder implements ApplicationContextAware { 
    	private static ApplicationContext applicationContext;
    
    	/** * 实现ApplicationContextAware接口的context注入函数， 将其存入静态变量. */
    	@Override
    	public void setApplicationContext(ApplicationContext applicationContext) throws BeansException { 
    		SpringContextHolder.applicationContext = applicationContext;
    
    	}
    
    	/** * 从静态变量ApplicationContext中取得Bean， 主动转型为所赋值对象的类型 * org.springframework.beans.factory.BeanFactory.getBean(String) */
    	@SuppressWarnings("unchecked")
    	public static <T> T getBean(String name) { 
    		checkApplicationContext();
    		return (T) applicationContext.getBean(name);
    	}
    
    	/** * 从静态变量ApplicationContext中取得Bean， 主动转型为所赋值对象的类型. 若是有多个Bean合适Class， 取出第一个. * org.springframework.beans.factory.BeanFactory.getBean(Class<T>) */
    	@SuppressWarnings("unchecked")
    	public static <T> T getBean(Class<T> clazz) { 
    		checkApplicationContext();
    		Map beanMaps = applicationContext.getBeansOfType(clazz);
    		if (beanMaps != null && !beanMaps.isEmpty()) { 
    			return (T) beanMaps.values().iterator().next();
    		} else { 
    			return null;
    		}
    	}
    
    	private static void checkApplicationContext() { 
    		if (applicationContext == null) { 
    			throw new IllegalStateException("applicaitonContext未注入，请在applicationContext.xml中定义SpringContextHolder");
    		}
    	}
    }

## ApplicationContextAware源码 ##

package org.springframework.context;
    
    import org.springframework.beans.BeansException;
    import org.springframework.beans.factory.Aware;
    
    public interface ApplicationContextAware extends Aware { 
    
    	/** * Set the ApplicationContext that this object runs in. * Normally this call will be used to initialize the object. * <p>Invoked after population of normal bean properties but before an init callback such * as {@link org.springframework.beans.factory.InitializingBean#afterPropertiesSet()} * or a custom init-method. Invoked after {@link ResourceLoaderAware#setResourceLoader}, * {@link ApplicationEventPublisherAware#setApplicationEventPublisher} and * {@link MessageSourceAware}, if applicable. * @param applicationContext the ApplicationContext object to be used by this object * @throws ApplicationContextException in case of context initialization errors * @throws BeansException if thrown by application context methods * @see org.springframework.beans.factory.BeanInitializationException */
    	void setApplicationContext(ApplicationContext applicationContext) throws BeansException;
    
    }

## 获取实例 ##

private CourierInfoConfig courierInfoConfig = SpringContextHolder.getBean(CourierInfoConfig.class);