Spring学习(二十二-自定义组件（获取IOC容器等等）

本是古典何须时尚 2024-02-19 16:06 64阅读 0赞

自定义组件想要使用Spring容器底层的一些组件（ApplicationContext，BeanFactory等等）。
        自定义组件实现xxxAware；在创建对象的时候，会调用接口规定的方法注入相关组件；Aware；
        把Spring底层一些组件注入到自定义的Bean中；
        xxxAware：功能使用xxxProcessor进行处理；
    解析： ApplicationContextAware==》ApplicationContextAwareProcessor；

Aware：

public interface Aware {
    
    }

继承：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70][]

测试：

@Component
    public class Red implements ApplicationContextAware,BeanNameAware,EmbeddedValueResolverAware {
    
    	private ApplicationContext applicationContext;
    
    	public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
    		// 获取IOC容器
    		System.out.println("传入的ioc："+applicationContext);
    		this.applicationContext = applicationContext;
    	}
    
    	/**
    	 * 获取当前bean的名字
    	 * @param name
    	 */
    	public void setBeanName(String name) {
    		// TODO Auto-generated method stub
    		System.out.println("当前bean的名字："+name);
    	}
    
    	/**
    	 * EmbeddedValueResolverAware
    	 * @param resolver
    	 */
    	public void setEmbeddedValueResolver(StringValueResolver resolver) {
    		//解析的字符串
    		String resolveStringValue = resolver.resolveStringValue("你好 ${os.name} 我是 #{20*18}");
    		System.out.println("解析的字符串："+resolveStringValue);
    	}
    }

配置类：

@Configuration
    @ComponentScan({"com.spring"})
    public class MainConifgOfAutowired {
    
    }

测试类：

@Test
    	public void test01(){
    		AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConifgOfAutowired.class);
    
    		System.out.println(applicationContext);
    		applicationContext.close();
    	}

结果：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70 1][]

Aware实现类都有相关的process对象进行处理，比如ApplicationContextAware==》ApplicationContextAwareProcessor进行解析。

ApplicationContextAwareProcessor源码分析：

/**
    *后置处理器
    */
    class ApplicationContextAwareProcessor implements BeanPostProcessor {
    
    	private final ConfigurableApplicationContext applicationContext;
    
    	private final StringValueResolver embeddedValueResolver;
    
    
    	/**
    	 *
    	 给容器创建一个ApplicationContextAwareProcessor对象
    	 */
    	public ApplicationContextAwareProcessor(ConfigurableApplicationContext applicationContext) {
    		this.applicationContext = applicationContext;
    		this.embeddedValueResolver = new EmbeddedValueResolver(applicationContext.getBeanFactory());
    	}
    
    
    	@Override
    	public Object postProcessBeforeInitialization(final Object bean, String beanName) throws BeansException {
    		AccessControlContext acc = null;
            //安全检查
    		if (System.getSecurityManager() != null &&
    				(bean instanceof EnvironmentAware || bean instanceof EmbeddedValueResolverAware ||
    						bean instanceof ResourceLoaderAware || bean instanceof ApplicationEventPublisherAware ||
    						bean instanceof MessageSourceAware || bean instanceof ApplicationContextAware)) {
    			acc = this.applicationContext.getBeanFactory().getAccessControlContext();
    		}
    
    		if (acc != null) {
    		    //权限检查
    			AccessController.doPrivileged(new PrivilegedAction<Object>() {
    				@Override
    				public Object run() {
    					invokeAwareInterfaces(bean);
    					return null;
    				}
    			}, acc);
    		}
    		else {
    		    //执行接口
    			invokeAwareInterfaces(bean);
    		}
    
    		return bean;
    	}
    
    	private void invokeAwareInterfaces(Object bean) {
    	    //判断对象是否是Aware子类
    		if (bean instanceof Aware) {
    		     //判断是否是EnvironmentAware子类
    			if (bean instanceof EnvironmentAware) {
    			     //设置环境
    				((EnvironmentAware) bean).setEnvironment(this.applicationContext.getEnvironment());
    			}
    			if (bean instanceof EmbeddedValueResolverAware) {
    				((EmbeddedValueResolverAware) bean).setEmbeddedValueResolver(this.embeddedValueResolver);
    			}
    			if (bean instanceof ResourceLoaderAware) {
    				((ResourceLoaderAware) bean).setResourceLoader(this.applicationContext);
    			}
    			if (bean instanceof ApplicationEventPublisherAware) {
    				((ApplicationEventPublisherAware) bean).setApplicationEventPublisher(this.applicationContext);
    			}
    			if (bean instanceof MessageSourceAware) {
    				((MessageSourceAware) bean).setMessageSource(this.applicationContext);
    			}
    			判断是否是ApplicationContextAware子类
    			if (bean instanceof ApplicationContextAware) {
    			     //设置容器对象
    				((ApplicationContextAware) bean).setApplicationContext(this.applicationContext);
    			}
    		}
    	}
    
    	@Override
    	public Object postProcessAfterInitialization(Object bean, String beanName) {
    		return bean;
    	}
    
    }

后置处理器流程可以看第Spring(十六)-BeanPostProcessor原理。

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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70 1]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/fb6657f32a674381a901d4fc205079ed.png