【尚硅谷】spring学习笔记（11）：FactoryBean

实现 FactoryBean 接口在 Spring IOC 容器中配置 Bean

• Spring 中有两种类型的 Bean, 一种是普通Bean, 另一种是工厂Bean, 即FactoryBean. 
• 工厂 Bean 跟普通Bean不同, 其返回的对象不是指定类的一个实例, 其返回的是该工厂 Bean 的 getObject 方法所返回的对象 

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;
	}
	
	@Override
	public String toString() {
		return "Car [brand=" + brand + ", price=" + price + "]";
	}
	
	
	public Car(String brand, double price) {
		super();
		this.brand = brand;
		this.price = price;
	}
	
	public Car() {
		System.out.println("car的构造器");
	}	
}

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 String getBrand() {
		return brand;
	}

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

	//还回bean对象	
	@Override
	public Car getObject() throws Exception {
		return new Car(brand,600000);
	}

	//还回bean的类型
	@Override
	public Class<?> getObjectType() {
		return Car.class;
	}

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

<?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
        
                但实际还回的实例确实FactoryBean的getObject()方法还回的实例
    -->
    <bean id="car" class="com.atguigu.spring.beans.factorybean.CarFactoryBean">
         <property name="brand" value="宝马"></property>
    </bean>

</beans>

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 apl = new ClassPathXmlApplicationContext("beans-beanfactory.xml");
		
		Car car = (Car) apl.getBean("car");
		
		System.out.println(car);
	}

}

结果：

六月 13, 2018 2:18:44 下午 org.springframework.context.support.AbstractApplicationContext prepareRefresh
信息: Refreshing org[email protected]6193b845: startup date [Wed Jun 13 14:18:44 CST 2018]; root of context hierarchy
六月 13, 2018 2:18:44 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [beans-beanfactory.xml]
Car [brand=宝马, price=600000.0]