Spring通过FactoryBean配置Bean

笔记内容及代码来源于尚硅谷的免费在线课

地址：http://www.gulixueyuan.com/my/course/46

FactoryBean.class有3个方法

getObject() 返回bean本身

getObjectType() 返回bean的实例

isSingleton 返回bean是否为单例

 

有时在配置一个bean的时候会用到IOC容器的其他bean，这个是有用factorybean配置是最合适的

Car.java，和Factory的Car类没有区别

package com.atguigu.spring.beans.factorybean;

public class Car {
    private String brand;
    private double price;

    public String getBrand() {
        return brand;
    }

    public void setBrand(String brand) {
        this.brand = brand;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    public Car(String brand, double price) {
        this.brand = brand;
        this.price = price;
    }

    public Car() {
        System.out.println("Car's Constructor...");
    }

    @Override
    public String toString() {
        return "Car{" +
                "brand='" + brand + '\'' +
                ", price=" + price +
                '}';
    }
}

 

CarFactoryBean.java   自定义的FactoryBean需要实现FactoryBean接口

 

package com.atguigu.spring.beans.factorybean;


import org.springframework.beans.factory.FactoryBean;


//自定义的FactoryBean需要实现FactoryBean接口
public class CarFactoryBean implements FactoryBean<Car> {

    private String brand;

    public void setBrand(String brand) {
        this.brand = brand;
    }

    //返回bean的对象
    public Car getObject() throws Exception {
        return new Car(brand,500000);
    }

    /**
     * 返回bean的类型
     */
    public Class<?> getObjectType() {
        return Car.class;
    }

    public boolean isSingleton() {
        return true;
    }
}

 

 

beans-beanfactory.xml

<?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">


    <!--
        通过FactoryBean来配置Bean的实例
        class：指向FactoryBean的全类名
        property：配置FactoryBean的属性

        但实际返回的实例确实FactorBean的getObject()方法返回的实例！
    -->
    <bean id="car" class="com.atguigu.spring.beans.factorybean.CarFactoryBean">
        <property name="brand" value="BMW"></property>
    </bean>
</beans>

 

main.java

package com.atguigu.spring.beans.factorybean;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class main {
    public static void main(String[] args) {

        ApplicationContext ctx = new ClassPathXmlApplicationContext("beans-beanfactory.xml");

        Car car = (Car) ctx.getBean("car");
        System.out.println(car);
    }
}