一文详解Spring如何控制Bean注入的顺序

@Component
public class CDemo1 {
    private String name = "cdemo 1";
 
    public CDemo1(CDemo2 cDemo2) {
        System.out.println(name);
    }
}
 
@Component
public class CDemo2 {
    private String name = "cdemo 2";
 
    public CDemo2() {
        System.out.println(name);
    }
}

@DependsOn("rightDemo2")
@Component
public class RightDemo1 {
    private String name = "right demo 1";
 
    public RightDemo1() {
        System.out.println(name);
    }
}
 
@Component
public class RightDemo2 {
    private String name = "right demo 2";
 
    public RightDemo2() {
        System.out.println(name);
    }
}

@DependsOn("rightDemo2")
@Component
public class RightDemo1 {
    private String name = "right demo 1";
 
    @Autowired
    private RightDemo2 rightDemo2;
 
    public RightDemo1() {
        System.out.println(name);
    }
 
    @PostConstruct
    public void init() {
        System.out.println(name + " _init");
    }
}
 
@Component
public class RightDemo2 {
    private String name = "right demo 2";
 
    @Autowired
    private RightDemo1 rightDemo1;
 
    public RightDemo2() {
        System.out.println(name);
    }
 
    @PostConstruct
    public void init() {
        System.out.println(name + " _init");
    }
}

@Component
public class HDemo1 {
    private String name = "h demo 1";
 
    public HDemo1() {
        System.out.println(name);
    }
}
 
@Component
public class HDemo2 {
    private String name = "h demo 2";
 
    public HDemo2() {
        System.out.println(name);
    }
}

@Component
public class DemoBeanPostProcessor extends InstantiationAwareBeanPostProcessorAdapter implements BeanFactoryAware {
    private ConfigurableListableBeanFactory beanFactory;
    @Override
    public void setBeanFactory(BeanFactory beanFactory) {
        if (!(beanFactory instanceof ConfigurableListableBeanFactory)) {
            throw new IllegalArgumentException(
                    "AutowiredAnnotationBeanPostProcessor requires a ConfigurableListableBeanFactory: " + beanFactory);
        }
        this.beanFactory = (ConfigurableListableBeanFactory) beanFactory;
    }
 
    @Override
    @Nullable
    public Object postProcessBeforeInstantiation(Class<?> beanClass, String beanName) throws BeansException {
        // 在bean实例化之前做某些操作
        if ("HDemo1".equals(beanName)) {
            HDemo2 demo2 = beanFactory.getBean(HDemo2.class);
        }
        return null;
    }
}

@Component
public class DemoBeanPostProcessor extends InstantiationAwareBeanPostProcessorAdapter 
                                   implements BeanFactoryAware {
    private ConfigurableListableBeanFactory beanFactory;
    @Override
    public boolean postProcessAfterInstantiation(Object bean, String beanName) throws BeansException {
        if ("application".equals(beanName)) {
            beanFactory.getBean(FDemo.class);
        }
        return true;
    }
}
 
@DependsOn("HDemo")
@Component
public class FDemo {
    private String name = "F demo";
 
    public FDemo() {
        System.out.println(name);
    }
}
 
@Component
public class HDemo {
    private String name = "H demo";
 
    public HDemo() {
        System.out.println(name);
    }
}