Java Spring @Lazy延迟注入源码案例详解

@Service
public class NormalService1 {

	@Autowired
	@Lazy
	private MyService myService;

	public void doSomething() {
		myService.getName();
	}
}

public Object resolveDependency(DependencyDescriptor descriptor, @Nullable String requestingBeanName,
			@Nullable Set<String> autowiredBeanNames, @Nullable TypeConverter typeConverter) throws BeansException {

		descriptor.initParameterNameDiscovery(getParameterNameDiscoverer());
		if (Optional.class == descriptor.getDependencyType()) {
			return createOptionalDependency(descriptor, requestingBeanName);
		}
		else if (ObjectFactory.class == descriptor.getDependencyType() ||
				ObjectProvider.class == descriptor.getDependencyType()) {
			return new DependencyObjectProvider(descriptor, requestingBeanName);
		}
		else if (javaxInjectProviderClass == descriptor.getDependencyType()) {
			return new Jsr330Factory().createDependencyProvider(descriptor, requestingBeanName);
		}
		else {
			//如果注入属性添加了@Lazy，懒加载，此时spring会根据具体类型搞个cglib代理类
			Object result = getAutowireCandidateResolver().getLazyResolutionProxyIfNecessary(
					descriptor, requestingBeanName);
			if (result == null) {
				result = doResolveDependency(descriptor, requestingBeanName, autowiredBeanNames, typeConverter);
			}
			return result;
		}
	}

protected Object buildLazyResolutionProxy(final DependencyDescriptor descriptor, final @Nullable String beanName) {
		Assert.state(getBeanFactory() instanceof DefaultListableBeanFactory,
				"BeanFactory needs to be a DefaultListableBeanFactory");
		final DefaultListableBeanFactory beanFactory = (DefaultListableBeanFactory) getBeanFactory();
		TargetSource ts = new TargetSource() {
			@Override
			public Class<?> getTargetClass() {
				return descriptor.getDependencyType();
			}
			@Override
			public boolean isStatic() {
				return false;
			}
			@Override
			public Object getTarget() {
				Object target = beanFactory.doResolveDependency(descriptor, beanName, null, null);
				/**
				something valid
				**/
				return target;
			}
			@Override
			public void releaseTarget(Object target) {
			}
		};
		ProxyFactory pf = new ProxyFactory();
		pf.setTargetSource(ts);
		Class<?> dependencyType = descriptor.getDependencyType();
		if (dependencyType.isInterface()) {
			pf.addInterface(dependencyType);
		}
		return pf.getProxy(beanFactory.getBeanClassLoader());
	}

Object target = beanFactory.doResolveDependency(descriptor, beanName, null, null);