SpringBoot @PostConstruct和@PreDestroy的使用说明

@Component
public class TestComponent {
    public TestComponent(){
        System.out.println("TestComponent 构造函数");
    }
    @PostConstruct
    public void init(){
        System.out.println("TestComponent PostConstruct");
    }
}

public interface MyService {
    void Hello(String name);
}

@Service
public class MyServiceImpl implements MyService {
    public MyServiceImpl(){
        System.out.println("MyServiceImpl 构造函数");
    }
    @PostConstruct
    public void init(){
        System.out.println("MyServiceImpl PostConstruct");
    }
    @Override
    public void Hello(String name) {
        System.out.println("Hello " + name);
    }
}

    @Autowired
    private MyService myService;

@Component
public class TestComponent {
    @Autowired
    private MyService myService;
    public TestComponent(){
        System.out.println("TestComponent 构造函数");
        //写在这里必定抛出异常，此时 myService == null
		//myService.Hello("张三");
    }
    @PostConstruct
    public void init(){
        System.out.println("TestComponent PostConstruct");
        //在这里调用MySerice方法才正确
        myService.Hello("张三");
    }
}

    @PreDestroy
    public void destroy(){
        System.out.println("TestComponent 对象被销毁了");
    }

@SpringBootApplication
public class AnnotationTestApplication {
    public static void main(String[] args) {
        ConfigurableApplicationContext ctx = SpringApplication.run(AnnotationTestApplication.class, args);
		
        try {
            Thread.sleep(10 * 1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        ctx.close();
    }
}