Spring中的InitializingBean接口

使用方法

@Slf4j
@Component
public class MyBean implements InitializingBean {public MyBean() {log.info("===================> 构造方法");}@Overridepublic void afterPropertiesSet() throws Exception {log.info("===================> afterPropertiesSet方法");}
}

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Spring中的Bean注入流程

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afterPropertieSet()和init-method

在Spring初始化bean的时候，如果该bean实现了InitializingBean接口，并且同时在配置了init-method，系统则是先调用afterPropertieSet()方法，然后再调用init-method中指定的方法。

通过查看Spring加载bean的源码类AbstractAutowiredCapableBeanFactory可以看出：

protected void invokeInitMethods(String beanName, Object bean, @Nullable RootBeanDefinition mbd)throws Throwable {// 判断bean是否实现InitializingBean接口boolean isInitializingBean = (bean instanceof InitializingBean);if (isInitializingBean && (mbd == null || !mbd.isExternallyManagedInitMethod("afterPropertiesSet"))) {if (logger.isTraceEnabled()) {logger.trace("Invoking afterPropertiesSet() on bean with name '" + beanName + "'");}if (System.getSecurityManager() != null) {try {AccessController.doPrivileged((PrivilegedExceptionAction<Object>) () -> {((InitializingBean) bean).afterPropertiesSet();return null;}, getAccessControlContext());}catch (PrivilegedActionException pae) {throw pae.getException();}}else {// 执行InitializingBean接口实现的方法((InitializingBean) bean).afterPropertiesSet();}}if (mbd != null && bean.getClass() != NullBean.class) {String initMethodName = mbd.getInitMethodName();if (StringUtils.hasLength(initMethodName) &&!(isInitializingBean && "afterPropertiesSet".equals(initMethodName)) &&!mbd.isExternallyManagedInitMethod(initMethodName)) {// 使用反射的方式来调用init-method指定的方法invokeCustomInitMethod(beanName, bean, mbd);}}
}