spring | FactoryBean

FactoryBean

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。
示例：
1.项目目录

2.Car.java

package com.atguigu.spring.factorybean;

public class Car {
    private String brand;
    private Double price;
    public String getBrand() {
        return brand;
    }
    public void setBrand(String brand) {
        this.brand = brand;
    }
    @Override
    public String toString() {
        return "Car [brand=" + brand + ", price=" + price + "]";
    }
    public Double getPrice() {
        return price;
    }
    public void setPrice(Double price) {
        this.price = price;
    }
    
}

3.MyFactory.java

package com.atguigu.spring.factorybean;

import org.springframework.beans.factory.FactoryBean;

public class MyFactory implements FactoryBean<Car>{
    @Override
    public Car getObject() throws Exception {
        Car car = new Car();
        car.setBrand("奥迪");
        car.setPrice(200000.0);
        return car;
    }

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

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

4.factory-bean.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">
    
    <!-- 工厂bean -->
    <bean id="factory" class="com.atguigu.spring.factorybean.MyFactory"></bean>
</beans>

5.Test.java

package com.atguigu.spring.factorybean;

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

public class Test {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        ApplicationContext ac = new ClassPathXmlApplicationContext("factory-bean.xml");
        Object bean = ac.getBean("factory");
        System.out.println(bean);
    }
}

6.运行结果
Car [brand=奥迪, price=200000.0]