spring FactoryBean配置Bean

Posted 2020-09-12

概要：

实例代码具体解释：

文件夹结构

Car.java

package com.coslay.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() {
		System.out.println("Car‘s Constructor...");
	}

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

}

CarFactoryBean.java

package com.coslay.beans.factorybean;

import org.springframework.beans.factory.FactoryBean;


//自己定义的FactoryBean须要实现 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
	@Override
	public Car getObject() throws Exception {
		return new Car("BMW",5000000);
	}
	
	//返回bean的类型
	@Override
	public Class<?> getObjectType() {
		return Car.class;
	}

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

Main.java

package com.coslay.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);
	}
}

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是FactoryBean的getObject()方法返回的实例
	 -->
	<bean id="car" class="com.coslay.beans.factorybean.CarFactoryBean">
		<property name="brand" value="BMW"></property>
	</bean>

</beans>