public class User {
    String username;
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    @Override
    public String toString() {
        return "User{" +
                "username='" + username + '\'' +
                '}';
    }
}

DefaultListableBeanFactory beanFactory=new DefaultListableBeanFactory();
        RootBeanDefinition rootBeanDefinition=new RootBeanDefinition(User.class);
        beanFactory.registerBeanDefinition("user",rootBeanDefinition);
        System.out.println(beanFactory.getBean("user",User.class));

 AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext();
        applicationContext.register(User.class);
        applicationContext.refresh();
        System.out.println(applicationContext.getBean("user", User.class));

@Retention(RetentionPolicy.RUNTIME)
@Documented
@Target(ElementType.CONSTRUCTOR)
public @interface MyAutowired {
}

public class User implements InitializingBean, DisposableBean {
    String username;
    //Spring為了降低對(duì)客戶代碼的侵入性，給bean的配置提供了init-method屬性，
    // 該屬性指定了在這一階段需要執(zhí)行的函數(shù)名。Spring便會(huì)在初始化階段執(zhí)行我們?cè)O(shè)置的函數(shù)。
    // init-method本質(zhì)上仍然使用了InitializingBean接口。
    public void init(){
        System.out.println(this.getClass().getSimpleName()+" 執(zhí)行自定義初始化方法");
    }
    public User() {
    }
    @MyAutowired
    public User(String username) {
        this.username = username;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    @Override
    public String toString() {
        return "User{" +
                "username='" + username + '\'' +
                '}';
    }
    @Override
    public void destroy() throws Exception {
        System.out.println("調(diào)用DisposableBean接口的destroy方法");
    }
    //afterPropertiesSet()這一階段也可以在bean正式構(gòu)造完成前增加我們自定義的邏輯，
    // 但它與前置處理不同，由于該函數(shù)并不會(huì)把當(dāng)前bean對(duì)象傳進(jìn)來，因此在這一步?jīng)]辦法處理對(duì)象本身，
    // 只能增加一些額外的邏輯。 若要使用它，我們需要讓bean實(shí)現(xiàn)該接口，把要增加的邏輯寫在該函數(shù)中。
    // 然后Spring會(huì)在前置處理完成后檢測(cè)當(dāng)前bean是否實(shí)現(xiàn)了該接口，并執(zhí)行afterPropertiesSet函數(shù)
    @Override
    public void afterPropertiesSet() throws Exception {
        System.out.println("調(diào)用afterPropertiesSet方法");
    }
}

public class MyTest {
    public static void main(String[] args) {
        DefaultListableBeanFactory beanFactory=new DefaultListableBeanFactory();
        //InstantiationAwareBeanPostProcessor接口在Bean對(duì)象實(shí)例化前的方法
        beanFactory.addBeanPostProcessor(new InstantiationAwareBeanPostProcessor() {
            public Object postProcessBeforeInstantiation(Class<?> beanClass, String beanName) throws BeansException {
                if(beanName.equals("user"))
                System.out.println(beanName+" Bean對(duì)象在實(shí)例化之前操作**");
                return null;
            }
        });
        //InstantiationAwareBeanPostProcessor接口在Bean對(duì)象實(shí)例化后的方法
        beanFactory.addBeanPostProcessor(new InstantiationAwareBeanPostProcessor() {
            public boolean postProcessAfterInstantiation(Object bean, String beanName) throws BeansException {
                if(beanName.equals("user"))
                System.out.println(beanName+" Bean對(duì)象在實(shí)例化之后操作**");
                return false;
            }
        });
        //使用自己自定義含有@MyAutowired注解的構(gòu)造方法，實(shí)例化Bean對(duì)象
        beanFactory.addBeanPostProcessor(new SmartInstantiationAwareBeanPostProcessor() {
            public Constructor<?>[] determineCandidateConstructors(Class<?> beanClass, String beanName) throws BeansException {
                if(beanName.equals("user"))
                System.out.println("實(shí)例化Bean對(duì)象");
                Constructor<?>[] declaredConstructors = beanClass.getDeclaredConstructors();
                List<Constructor<?>> collect = Arrays.stream(declaredConstructors).filter(i -> i.isAnnotationPresent(MyAutowired.class)).collect(Collectors.toList());
                Constructor[] constructors = collect.toArray(new Constructor[collect.size()]);
                return constructors.length>0?constructors:null;
            }
        });
        //BeanPostProcessor接口在Bean對(duì)象初始化之前的方法調(diào)用
        beanFactory.addBeanPostProcessor(new BeanPostProcessor() {
            @Override
            public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
                if(beanName.equals("user"))
                    System.out.println(beanName+" Bean對(duì)象在初始化之前操作**");
                return null;
            }
        });
       //BeanPostProcessor接口在Bean對(duì)象初始化之后的方法調(diào)用
        beanFactory.addBeanPostProcessor(new BeanPostProcessor() {
            @Override
            public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
                if(beanName.equals("user"))
                    System.out.println(beanName+" Bean對(duì)象在初始化之后操作**");
                return null;
            }
        });
        RootBeanDefinition rootBeanDefinition= (RootBeanDefinition) BeanDefinitionBuilder.rootBeanDefinition(User.class).setInitMethodName("init").getBeanDefinition();
        beanFactory.registerBeanDefinition("user",rootBeanDefinition);
        beanFactory.registerBeanDefinition("username", BeanDefinitionBuilder.genericBeanDefinition(String.class)
                .addConstructorArgValue("admin").getBeanDefinition());
        System.out.println(beanFactory.getBean("user",User.class));
        beanFactory.destroySingletons();
    }
}