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ApplicationContext ct = new ClassPathXmlApplicationContext("spring.xml");

public class Test2 { public static void main(String[] args) {
 UserController userController = new UserController(); class<? extends UserController> clazz = userController.getClass(); //获取当前controller的属性有哪些 Stream.of(clazz.getDeclaredFields()).forEach(field ->{ //判断一个属性值是否使用了@Autowired修饰 AutoWired annotation = field.getAnnotation(AutoWired.class); if (annotation!=null){ field.setAccessiable(true); //获取到属性类型，方便创建对象 Class<?> type = field.getType(); //创建具体对象 Object o = null; try { o = type.newInstance(); field.set(userController, 0); }catch (InstantiationException e){ e.printStackTrace(); }catch (IllegalAccessException e){ e.printStackTrace(); } } }); System.out.println(userController.getUserService()); }}

** * Interface to be implemented by objects used within a {@link BeanFactory} which * are themselves factories for individual objects. If a bean implements this * interface, it is used as a factory for an object to expose, not directly as a * bean instance that will be exposed itself. * * <p><b>NB: A bean that implements this interface cannot be used as a normal bean.</b> * A FactoryBean is defined in a bean style, but the object exposed for bean * references ({@link #getObject()}) is always the object that it creates. * * <p>FactoryBeans can support singletons and prototypes, and can either create * objects lazily on demand or eagerly on startup. The {@link SmartFactoryBean} * interface allows for exposing more fine-grained behavioral metadata. * * <p>This interface is heavily used within the framework itself, for example for * the AOP {@link org.springframework.aop.framework.ProxyFactoryBean} or the * {@link org.springframework.jndi.JndiObjectFactoryBean}. It can be used for * custom components as well; however, this is only common for infrastructure code. * * <p><b>{@code FactoryBean} is a programmatic contract. Implementations are not * supposed to rely on annotation-driven injection or other reflective facilities.</b> * {@link #getObjectType()} {@link #getObject()} invocations may arrive early in * the bootstrap process, even ahead of any post-processor setup. If you need access * other beans, implement {@link BeanFactoryAware} and obtain them programmatically. * * <p>Finally, FactoryBean objects participate in the containing BeanFactory's * synchronization of bean creation. There is usually no need for internal * synchronization other than for purposes of lazy initialization within the * FactoryBean itself (or the like). * * @author Rod Johnson * @author Juergen Hoeller * @since 08.03.2003 * @param <T> the bean type * @see org.springframework.beans.factory.BeanFactory * @see org.springframework.aop.framework.ProxyFactoryBean * @see org.springframework.jndi.JndiObjectFactoryBean */public interface FactoryBean<T> {

//返回由FactoryBean创建的bean实例，如果isSingleton()返回true，则该实例会放到Spring容器中单实例缓存池中。@NullableT getObject() throws Exception;//返回由FactoryBean创建的bean实例的作用域是singleton还是prototype。@NullableClass<?> getObjectType();//返回FactoryBean创建的bean类型。default boolean isSingleton() { return true;}