spring5 工厂bean

1.工厂bean

package com.cj.spring5;

import org.springframework.beans.factory.FactoryBean;

public class MyBean implements FactoryBean<Course> {
    //定义返回的bean
    @Override
    public Course getObject() throws Exception {
        Course course = new Course("好看的书");
        return course;
    }

    @Override
    public Class<?> getObjectType() {
        return null;
    }

    @Override
    public boolean isSingleton() {
        return false;
    }
}

 2.bean 的作用域

singleton 单例 获取xml文件时创建对象

prototype 多实例 getBean时创建对象

 3. bean 的生命周期

　　1.执行无参构造创建bean实例

　　2.set属性注入

　　初始化之前

　　3.初始化的方法

　　初始化之后

　　4.获取bean实例对象

　　5.执行销毁的方法

package com.cj.spring5;

public class Goods {
    private String name;
    public Goods(){
        System.out.println("1.无参构造");
    }

    public Goods(String name) {
        this.name = name;
    }

    public void setName(String name) {
        this.name = name;
        System.out.println("2.属性");
    }
    public void initMethod(){
        System.out.println("3.初始化");
    }
    public void destoryMethod(){
        System.out.println("5.销毁");
    }
}

public void test8(){
    //获取xml
    //ApplicationContext xml = new ClassPathXmlApplicationContext("bean4.xml");
    ClassPathXmlApplicationContext xml = new ClassPathXmlApplicationContext("bean4.xml");
    //获取对象
    Goods goods = xml.getBean("goods", Goods.class);
    System.out.println("4.获取bean实例");
    //调用
    xml.close();
    //System.out.println(goods.toString());
}

 <bean id="goods" class="com.cj.spring5.Goods" init-method="initMethod" destroy-method="destoryMethod">
     <property name="name" value="鱼干"/>
 </bean>

3.1 后置处理器

<bean id="myBeanPost" class="com.cj.spring5.MyBeanPost"/>

package com.cj.spring5;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.lang.Nullable;

public class MyBeanPost implements BeanPostProcessor {

    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("初始化之前");
        return null;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("初始化之后");
        return null;
    }
}