这篇文章描述了Spring整体的启动流程，并通过测试用例，演示了一些Spring的扩展点在Bean的生命周期中的使用。

测试代码

@Component
public class A implements SmartLifecycle {
    private boolean running;

    @Override
    public void start() {
        System.out.println("SmartLifecycle start...");
        this.running = true;
    }

    @Override
    public void stop() {
        System.out.println("SmartLifecycle stop...");
    }

    @Override
    public boolean isRunning() {
        System.out.println("SmartLifecycle isRunning...");
        return this.running;
    }
}

public class B implements InitializingBean {

    @PostConstruct
    public void postConstruct() {
        System.out.println("PostConstruct ...");
    }

    @Override
    public void afterPropertiesSet() throws Exception {
        System.out.println("afterPropertiesSet ...");
    }

    public void init() {
        System.out.println("init method ...");
    }

    @PreDestroy
    public void preDestroy() {
        System.out.println("PreDestroy ...");
    }

    public void destroy() {
        System.out.println("destroy method ...");
    }
}

@Component
@EnableAsync
public class C {

    @Async
    public void print() {
        for (int i = 0; i < 10; i++) {
            System.out.println("test ...");
        }
    }
}

@Configuration
@ComponentScan("com.francis.test")
public class JavaConfig {

    @Bean(initMethod = "init", destroyMethod = "destroy")
    public B b() {
        return new B();
    }

    @Bean
    public TaskExecutor taskExecutor() {
        return new ThreadPoolTaskExecutor();
    }
}

public class Test {
    public static void main(String[] args) {
        AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(JavaConfig.class);
        applicationContext.getBean(C.class).print();
        System.out.println("在调用 com.francis.test.C.print() 之前打印这句话说明异步生效，否则是同步");
        applicationContext.close();
    }
}

整体流程

一张图搞懂Spring启动流程和Bean的生命周期_ide