Spring 中BeanFactory和FactoryBean有什么不同之处呢?

转自:

http://www.java265.com/JavaFramework/Spring/202109/964.html

下文笔者将讲述Spring Framework中BeanFactory和FactoryBean的区别点，如下所示:

BeanFactory简介

BeanFactory是所有Spring容器的根接口
此接口为所有的Spring容器定义了一套标准(IOC容器定义了一套标准)
常见的方法如下所示:

BeanFactory常见的实现类(包括抽象类)

BeanFactory的使用方法

运用ClassPathXmlApplicationContext读取spring的配置文件获取一个实例对应上下文对象

ApplicationContext context = new ClassPathXmlApplicationContext(new String[] {"applicationContext.xml"});
BeanFactory factory = (BeanFactory) context;

FactoryBean

FactoryBean是SpringIOC容器中创建Bean的一种形式
采用FactoryBean的方式创建Spring Bean,可以减少xml的配置

FactoryBean中常见的方法

FactoryBean中常用的类

例:
FactoryBean创建SpringBean的示例分享

Spring XML方式  application.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="demo" class="com.java265.Person">
        <property name="age" value="88"/>
        <property name="name" value="Java265"/>
    </bean>

    <bean id="demoFromFactory" class="com.java265.PersonFactoryBean">
        <property name="str" value="99,init from factory"/>
    </bean>
</beans>


personFactoryBean.java

package com.java265;

import com.java265.Person;
import org.springframework.beans.factory.FactoryBean;

import java.util.Objects;

 
public class PersonFactoryBean implements FactoryBean<Person> {

    /**
     * 初始化Str
     */
    private String str;

    @Override
    public Person getObject() throws Exception {
        //这里我需要获取对应参数
        Objects.requireNonNull(str);
        String[] split = str.split(",");
        Person p=new Person();
        p.setAge(Integer.parseInt(split[0]));
        p.setName(split[1]);
        //这里可能需要还要有其他复杂事情需要处理
        return p;
    }

    @Override
    public Class<?> getObjectType() {
        return Person.class;
    }

    public String getInitStr() {
        return str;
    }

    public void setInitStr(String str) {
        this.str = str;
    }
}


main方法

package com.java265.factory;

import com.java265.Person;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.FactoryBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * BeanFactory 例子
 
 */
public class SpringBeanFactoryMain {

    public static void main(String[] args) {
        //这个是BeanFactory
        BeanFactory beanFactory = new ClassPathXmlApplicationContext("application.xml");
        //获取对应的对象化
        Object demo = beanFactory.getBean("demo");
        System.out.println(demo instanceof Person);
        System.out.println(demo);
         //获取从工厂Bean中获取对象
        Person demoFromFactory = beanFactory.getBean("demoFromFactory", Person.class);
        System.out.println(demoFromFactory);


        //获取对应的personFactory
        Object bean = beanFactory.getBean("&demoFromFactory");

        //将Spring使用xml生成的bean同FactoryBean生成的Bean进行比较
        System.out.println(bean instanceof PersonFactoryBean);
 
       PersonFactoryBean factoryBean=(PersonFactoryBean) bean;
        System.out.println("初始化参数为："+factoryBean.getInitStr());
    }
}
------运行以上代码，将输出以下信息-----
true
Person{name="Java265", age=88}
Person{name="init from factory", age=99}
true
初始化参数为：99,init from factory

BeanFactory同FactoryBean的区别:
   BeanFactory:负责生产和管理Bean的一个工厂接口，提供Spring Ioc容器标准
   FactoryBean: 一种Bean创建的一种方式，对Bean的一种扩展
        可以直接使用代码的方式创建一个SpringBean