Spring 生命周期各种初始化方法执行顺序

我不是女神ヾ 2022-03-15 11:40 545阅读 0赞

BeanConfigAndLifeCycle

package com.study.spring.config;
    
    import com.study.spring.bean.Cat;
    import com.study.spring.bean.Dog;
    import com.study.spring.bean.Pet;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    
    @Configuration
    public class BeanConfigAndLifeCycle {
    
        /**
         *  执行顺序: Construct(构造器) > @postConstruct > InitializingBean接口 > @Bean(initMethod) > BeanPostProcessor.postProcessBeforeInitialization
         *  执行顺序: @preDestroy >DisposableBean接口 > @Bean(destroyMethod)
         * 1）、指定初始化和销毁方法；
         * 		通过@Bean指定init-method和destroy-method；
         * 2）、通过让Bean实现InitializingBean（定义初始化逻辑），
         * 				DisposableBean（定义销毁逻辑）;
         * 3）、可以使用JSR250；
         * 		通过@PostConstruct：在bean创建完成并且属性赋值完成；来执行初始化方法
         * 		通过@PreDestroy：在容器销毁bean之前通知我们进行清理工作
         * 4）、BeanPostProcessor【interface】：bean的后置处理器；
         * 		在bean初始化前后进行一些处理工作；
         * 		postProcessBeforeInitialization:在初始化之前工作
         * 		postProcessAfterInitialization:在初始化之后工作
         *
         * 	 * Spring底层对 BeanPostProcessor 的使用；
         *  * 		bean赋值，注入其他组件，@Autowired，生命周期注解功能，@Async,xxx BeanPostProcessor;
         * @return
         */
        //@Bean(initMethod = "running", destroyMethod = "back")
        @Bean(initMethod = "running", destroyMethod = "back")
        public Dog dog() {
            return new Dog();
        }
    
    
        //@Bean
        public Cat cat() {
            return new Cat();
        }
    }

Dog

package com.study.spring.bean;
    
    import org.springframework.beans.BeansException;
    import org.springframework.beans.factory.DisposableBean;
    import org.springframework.beans.factory.InitializingBean;
    import org.springframework.beans.factory.config.BeanPostProcessor;
    
    import javax.annotation.PostConstruct;
    import javax.annotation.PreDestroy;
    
    public class Dog implements Pet,BeanPostProcessor, InitializingBean, DisposableBean {
    
        public Dog() {
            System.out.println("dog is Construct ing...");
        }
    
        @Override
        public void running() {
            System.out.println("dog is running...");
        }
    
        @Override
        public void back() {
            System.out.println("dog is back...");
        }
    
        @Override
        public void destroy() throws Exception {
            System.out.println("dog is destroy()");
        }
    
        @Override
        public void afterPropertiesSet() throws Exception {
            System.out.println("dog is afterPropertiesSet()...");
        }
    
        @PostConstruct
        public void postConstruct() throws Exception {
            System.out.println("dog is postConstruct()");
        }
        @PreDestroy
        public void preDestroy() throws Exception {
            System.out.println("dog is preDestroy()");
        }
    
        @Override
        public Object postProcessBeforeInitialization(Object o, String s) throws BeansException {
            System.out.println("dog is postProcessBeforeInitialization()" + o);
            return o;
        }
    
        @Override
        public Object postProcessAfterInitialization(Object o, String s) throws BeansException {
            System.out.println("dog is postProcessAfterInitialization()" + o);
            return o;
        }
    
    }

初始化执行顺序:

Construct(构造器) > @postConstruct > InitializingBean接口 > @Bean(initMethod) > BeanPostProcessor.postProcessBeforeInitialization > BeanPostProcessor.postProcessAfterInitialization

销毁方法执行顺序:

@preDestroy >DisposableBean接口 > @Bean(destroyMethod)

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InitializingBean接口 > @Bean(initMethod)执行顺序原因:

### AbstractAutowireCapableBeanFactory ###

protected void invokeInitMethods(String beanName, final Object bean, RootBeanDefinition mbd)
    			throws Throwable {
    
    		boolean isInitializingBean = (bean instanceof InitializingBean);
    		if (isInitializingBean && (mbd == null || !mbd.isExternallyManagedInitMethod("afterPropertiesSet"))) {
    			if (logger.isDebugEnabled()) {
    				logger.debug("Invoking afterPropertiesSet() on bean with name '" + beanName + "'");
    			}
    			if (System.getSecurityManager() != null) {
    				try {
    					AccessController.doPrivileged(new PrivilegedExceptionAction<Object>() {
    						@Override
    						public Object run() throws Exception {
    							((InitializingBean) bean).afterPropertiesSet();
    							return null;
    						}
    					}, getAccessControlContext());
    				}
    				catch (PrivilegedActionException pae) {
    					throw pae.getException();
    				}
    			}
    			else {
    				((InitializingBean) bean).afterPropertiesSet();
    			}
    		}
    
    		if (mbd != null) {
    			String initMethodName = mbd.getInitMethodName();
    			if (initMethodName != null && !(isInitializingBean && "afterPropertiesSet".equals(initMethodName)) &&
    					!mbd.isExternallyManagedInitMethod(initMethodName)) {
    				invokeCustomInitMethod(beanName, bean, mbd);
    			}
    		}
    	}

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