Bean的生命周期

总览

先来一张全局图

再来一个小demo

结构如下

@Component
public class User implements BeanNameAware , BeanFactoryAware, ApplicationContextAware, InitializingBean {

    private String name;
    //构造函数 
    public User() {
        System.out.println("User的构造方法执行了");
    }
    //依赖注入
    @Value("彭建飞")
    public void setName(String name) {
        System.out.println("setName方法执行了");
        this.name = name;
    }

    @Override //BeanNameAware接口
    public void setBeanName(String name) {
        System.out.println("setBeanName方法执行了");
    }

    @Override //BeanFactoryAware接口
    public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
        System.out.println("setBeanFactory方法执行了");
    }

    @Override //ApplicationContextAware接口
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        System.out.println("setApplicationContext方法执行了");
    }

    @PostConstruct //自定义增强，属于初始化方法
    public void init(){
        System.out.println("自定义init方法执行了");
    }

    @Override //InitializingBean，属于初始化方法
    public void afterPropertiesSet() throws Exception {
        System.out.println("afterPropertiesSet方法执行了");
    }

    @PreDestroy
    public void destroy(){
        System.out.println("destroy执行了");
    }
}

@Component
public class MyBeanPostProcessor implements BeanPostProcessor {
    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        if(beanName.equals("user")){
            System.out.println("postProcessBeforeInitialization方法执行了->user对象初始化方法前开始增强...");
        }
        return bean;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        if(beanName.equals("user")){
            System.out.println("postProcessBeforeInitialization方法执行了->user对象初始化方法后开始增强...");
            //cglib代理对象
            Enhancer enhancer = new Enhancer();
            //设置需要代理的类
            enhancer.setSuperclass(bean.getClass());
            //设置回调方法，增强方法
            enhancer.setCallback(new InvocationHandler() {
                @Override
                public Object invoke(Object o, Method method, Object[] objects) throws Throwable {
                    System.out.println("执行增强方法");
                    return method.invoke(method,objects);
                }
            });
        }
        return bean;
    }
}

@Component
@ComponentScan("com.guigu.beanlife/lifecycle")
public class SpringConfig {
}

public class BeanLifeTest {
    public static void main(String[] args) {
        AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(SpringConfig.class);
        User user = ctx.getBean(User.class);
        System.out.println(user);
    }
}

输出

User的构造方法执行了
setName方法执行了
setBeanName方法执行了
setBeanFactory方法执行了
setApplicationContext方法执行了
postProcessBeforeInitialization方法执行了->user对象初始化方法前开始增强...
自定义init方法执行了
afterPropertiesSet方法执行了
postProcessBeforeInitialization方法执行了->user对象初始化方法后开始增强...
User的构造方法执行了

总结