为啥要使用FactoryBean：
在配置Bean的时候，需要用到IOC容器中的其它Bean，这个时候使用FactoryBean配置最合适。
public class Car {
private String brand;
private double price;
public Car() {
System.out.println("com.cn.Car's Constructor");
}
public Car(String brand, double price) {
this.brand = brand;
this.price = price;
}
public void setBrand(String brand) {
System.out.println("setBrand");
this.brand = brand;
}
public String getBrand() {
return brand;
}
public void setPrice(double price) {
this.price = price;
}
public double getPrice() {
return price;
}
@Override
public String toString() {
return "Car{" +
"brand='" + brand + '\'' +
", price=" + price +
'}';
}
}/**
* 自定义的FactoryBean需要实现FactoryBean接口
*/
public class CarFactoryBean implements FactoryBean<Car>{
//FactoryBean自己的属性
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", 500000);
} @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
但实际返回的实例是FactoryBean的getObject()方法返回的实例
-->
<bean id="car" class="factorybean.CarFactoryBean">
<property name="brand" value="BMW"></property>
</bean>
</beans>
public class Main {
public static void main(String[] args) {
ApplicationContext ctx = new ClassPathXmlApplicationContext("12-1.xml");
Car car = (Car) ctx.getBean("car");
System.out.println(car);
}
}aaarticlea/png;base64,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" alt="" />