Spring中通過FactoryBean來配置bean
一、說在前面
實現 FactoryBean 接口在 Spring IOC 容器中配置 Bean1、Spring 中有兩種類型的 Bean, 一種是普通Bean, 另一種是工廠Bean, 即FactoryBean。
2、工廠 Bean 跟普通Bean不同, 其返回的對象不是指定類的一個實例, 其返回的是該工廠 Bean 的 getObject 方法所返回的對象。
二、實例演示
Car類:
package com.at.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;
}
}
CarFactoryBean類:
package com.at.beans.factorybean;
import org.springframework.beans.factory.FactoryBean;
//自定義的CarFactoryBean需要實現FactoryBean接口
public class CarFactoryBean implements FactoryBean<Car>{
private String brand;
public void setBrand(String brand) {
this.brand = brand;
}
//返回bean的對象
public Car getObject() throws Exception {
return new Car(brand,500000);
}
//返回bean的類型
public Class<?> getObjectType() {
return Car.class;
}
//是不是單實例的
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">
<!--
通過FactoryBean來配置bean實例
class:指向FactoryBean的全類名
property:配置FactoryBean的屬性
但是實際上返回的實例確實FactoryBean的getObject()方法返回的實例
-->
<bean id="car" class="com.at.beans.factorybean.CarFactoryBean">
<property name="brand" value="Audi"></property>
</bean>
</beans>
ApplicationContext ctx = new ClassPathXmlApplicationContext("beans-factorybean.xml");
Car car = (Car) ctx.getBean("car");
System.out.println(car);
返回結果:
六月 01, 2017 5:07:34 下午 org.springframework.context.support.AbstractApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@1c49094: startup date [Thu Jun 01 17:07:34 CST 2017]; root of context hierarchy
六月 01, 2017 5:07:35 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [beans-factorybean.xml]
Car [brand=Audi, price=500000.0]
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