Spring中的一些常用接口

Posted 2020-10-11 网络终结者

一、ApplicationContextAware接口

public interface ApplicationContextAware extends Aware {
    void setApplicationContext(ApplicationContext var1) throws BeansException;
}

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二、ServletContextAware 接口

public interface ServletContextAware extends Aware {
    void setServletContext(ServletContext var1);
}

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三、InitializingBean 接口

public interface InitializingBean {
    void afterPropertiesSet() throws Exception;
}

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四、ApplicationListener<ApplicationEvent> 接口

public interface ApplicationListener<E extends ApplicationEvent> extends EventListener {
    void onApplicationEvent(E var1);
}

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执行顺序

@Component
public class StartupListener implements ApplicationContextAware, ServletContextAware,
        InitializingBean, ApplicationListener<ContextRefreshedEvent> {
 
    protected Logger logger = LogManager.getLogger();
 
    @Override
    public void setApplicationContext(ApplicationContext ctx) throws BeansException {
        logger.info("1 => StartupListener.setApplicationContext");
    }
 
    @Override
    public void setServletContext(ServletContext context) {
        logger.info("2 => StartupListener.setServletContext");
    }
 
    @Override
    public void afterPropertiesSet() throws Exception {
        logger.info("3 => StartupListener.afterPropertiesSet");
    }
 
    @Override
    public void onApplicationEvent(ContextRefreshedEvent evt) {
        logger.info("4.1 => MyApplicationListener.onApplicationEvent");
        if (evt.getApplicationContext().getParent() == null) {
            logger.info("4.2 => MyApplicationListener.onApplicationEvent");
        }
    }
 
}

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运行时，输出的顺序如下：

1 => StartupListener.setApplicationContext
2 => StartupListener.setServletContext
3 => StartupListener.afterPropertiesSet
4.1 => MyApplicationListener.onApplicationEvent
4.2 => MyApplicationListener.onApplicationEvent
4.1 => MyApplicationListener.onApplicationEvent