<bean id="myFactoryBean" class="com.ws.model.MyFactoryBean"></bean>
/**
* ,指定生产 User 对象
*/
public class MyFactoryBean implements FactoryBean<User> {
/**
* 当我们调用 context.getBean("myFactoryBean")时,实际调用此方法,返回的是User对象
* 如果需要获取myFactoryBean本身实例,那么需要context.getBean("&myFactoryBean")这样获取;
*
* 在spring容器构建完毕之后,User对象是不会实例化的(工厂bean已经实例化了),需要通过getBean才会触发实例化,
* 并根据是否单例决定保存到容器中(FactoryBeanRegistrySupport类),后续若是单例并且容器中有则直接返回
*/
@Override
public User getObject() throws Exception {
User user = new User();
user.setName("hello");
return user;
}
@Override
public Class<?> getObjectType() {
return User.class;
}
/**
* 默认是false,也就是scope="prototype"
* @return
*/
@Override
public boolean isSingleton() {
return true;
}
}
@Test
public void test() {
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
User bean =(User) context.getBean("myFactoryBean");
MyFactoryBean myFactoryBean =(MyFactoryBean) context.getBean("&myFactoryBean");
}
context.getBean("myFactoryBean");
context.getBean("&myFactoryBean");
//两种区别 :
//流程区别 : 开始同样根据key=myFactoryBean,从DefaultListableBeanFactory中获取MyFactoryBean实例,实例获取后对实例再次进行处理,
// 如果以&前缀开始,则直接返回MyFactoryBean实例;
// 如果不以&前缀开始,则走MyFactoryBean实例对象的getObject()方法获取User实例;
//源码如下