spring ioc 2

spring bean流程图，一个bean实例的加载全过程。示意图

代码演示：

package com.mr.li.test;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

import com.mr.li.config.AppConfig;
import com.mr.li.service.Person;
import com.mr.li.service.impl.Man;

import lombok.extern.slf4j.Slf4j;


@Slf4j
public class Test {

    public static void main(String[] args) {
        AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(AppConfig.class);
        Person person = ctx.getBean(Man.class);
        person.behavior();
        ctx.close();

    }
}

bean的加载过程

package com.mr.li.service.impl;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.BeanNameAware;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;

import com.mr.li.service.Animal;
import com.mr.li.service.Person;

/**
 * 
 * @describe 实现的这些springframework包下的类可重写他们的方法去自定义自己的一些实现，使用的IOC必须是实现了ApplicationContext接口的IOC否则不会调用这些方法。
 *
 * @author [e-mail]
 *
 * @date 2021-8-18 14:46:10
 */
@Component
public class Man implements Person, BeanNameAware, BeanFactoryAware, ApplicationContextAware, InitializingBean, DisposableBean{

    @Qualifier("cat")
    @Autowired
    private Animal animal;

    @Override
    public void behavior() {
        animal.behavior();
    }

    @Override
    public void destroy() throws Exception {
        System.out.println("DisposableBean.destroy bean销毁方法");
    }

    @Override
    public void afterPropertiesSet() throws Exception {
        System.out.println("InitializingBean.afterPropertiesSet bean初始化方法。在设置了所有bean属性并满足了BeanFactoryAware、ApplicationContextAware等之后，由包含的BeanFactory调用。");
    }

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        System.out.println("ApplicationContextAware.applicationContext 回调设置ioc对象，不过通常拿到此对象会用此对象初始化一些数据，并不会对此对象本身改变什么");
    }

    @Override
    public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
        System.out.println("BeanFactoryAware.setBeanFactory bean工厂对当前对象的回调,提供了beanFactory对象，可利用beanFactory做一些处理 ");
    }

    @Override
    public void setBeanName(String name) {
        System.out.println("BeanNameAware.setBeanName 在创建当前对象的时候设置当前对象的bean名称，设置好的名称是： " + name);
    }
}

前置处理器，和后置处理器回调方法

package com.mr.li.service.impl;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.stereotype.Component;

@Component
public class BeanPostProcessorExample implements BeanPostProcessor {

    /**
     * 可通过处理器过滤做些事情，如通过beanName可在加载类的时候过滤出某个类然后对其操作
     */
    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("前置处理器,在加载每个bean之前调用: " + bean.getClass().getSimpleName() + "    beanName: " + beanName);
        return BeanPostProcessor.super.postProcessBeforeInitialization(bean, beanName);
    }

    //注意，这个Bean后置处理器将对所有的Bean有效
    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("后置处理器，在加载每个bean之后调用: " + bean.getClass().getSimpleName() + "    beanName: " + beanName);
        return BeanPostProcessor.super.postProcessAfterInitialization(bean, beanName);
    }
}