Bean的自动注入及循环依赖问题

@Component
public class AnnotationAutowiredFiledBeanTest {
}

@Component
public class AnnotationAutowiredMethodBeanTest {
}

@Component
public class AutowiredInjectByTypeMethodBeanTest {
}

@Component
public class UpdateBeanInfoBeanFactoryPostProcessor implements BeanFactoryPostProcessor{
	@Override
	public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
		AbstractBeanDefinition a = (AbstractBeanDefinition) beanFactory.getBeanDefinition("a");
		a.setAutowireMode(2);
		//a.getPropertyValues().add("beanDefinitionPropertyValuesBeanTest",new BeanDefinitionPropertyValuesBeanTest());
	}
}

@Component("a")
public class SpringBeanInfoTest {
 
	//@Autowired作用在属性上进行注入
	@Autowired
	AnnotationAutowiredFiledBeanTest autowiredFiledBeanTest;
 
	//@Autowired作用在方法上进行注入
	@Autowired
	public void setAnnotationAutowiredMethodBeanTest(AnnotationAutowiredMethodBeanTest annotationAutowiredMethodBeanTest){
		System.out.println("AnnotationAutowiredMethodBeanTest=[{}]"+annotationAutowiredMethodBeanTest);
	}
 
	//使用自动注入（使用byType的模式）
	public void setAutowiredInjectByTypeMethodBeanTest(AutowiredInjectByTypeMethodBeanTest autowiredInjectByTypeMethodBeanTest){
		System.out.println("AutowiredInjectByTypeMethodBeanTest=[{}]"+autowiredInjectByTypeMethodBeanTest);
	}
 
 
 
 
	//用来打印@Autowired作用在属性上进行注入是否成功
	public void printf(){
		System.out.println("autowiredFiledBeanTest=[{}]"+autowiredFiledBeanTest);
	}
 
}

@Configuration
@ComponentScan("com.spring.demo.introspect")
public class App {
 
}

public class ApplicationTest {
 
 
@Test
	public void testSpringInject() throws NoSuchFieldException, IntrospectionException {
		AnnotationConfigApplicationContext context
				= new AnnotationConfigApplicationContext();
		context.reGISter(App.class);
		context.refresh();
		context.getBean(SpringBeanInfoTest.class).printf();
    }
}

@Component
public class UpdateBeanInfoBeanFactoryPostProcessor implements BeanFactoryPostProcessor{
	@Override
	public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
		AbstractBeanDefinition a = (AbstractBeanDefinition) beanFactory.getBeanDefinition("a");
		//a.setAutowireMode(2);
		//a.getPropertyValues().add("beanDefinitionPropertyValuesBeanTest",new BeanDefinitionPropertyValuesBeanTest());
	}
}

public class BeanDefinitionPropertyValuesBeanTest {
}

@Component
public class UpdateBeanInfoBeanFactoryPostProcessor implements BeanFactoryPostProcessor{
	@Override
	public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
		AbstractBeanDefinition a = (AbstractBeanDefinition) beanFactory.getBeanDefinition("a");
		
		a.getPropertyValues().add("beanDefinitionPropertyValuesBeanTest",new BeanDefinitionPropertyValuesBeanTest());
	}
}

@Component("a")
public class SpringBeanInfoTest {
 
	//@Autowired作用在属性上进行注入
	@Autowired
	AnnotationAutowiredFiledBeanTest autowiredFiledBeanTest;
 
	//@Autowired作用在方法上进行注入
	@Autowired
	public void setAnnotationAutowiredMethodBeanTest(AnnotationAutowiredMethodBeanTest annotationAutowiredMethodBeanTest){
		System.out.println("AnnotationAutowiredMethodBeanTest=[{}]"+annotationAutowiredMethodBeanTest);
	}
 
	//使用自动注入（使用byType的模式）
	public void setAutowiredInjectByTypeMethodBeanTest(AutowiredInjectByTypeMethodBeanTest autowiredInjectByTypeMethodBeanTest){
		System.out.println("AutowiredInjectByTypeMethodBeanTest=[{}]"+autowiredInjectByTypeMethodBeanTest);
	}
 
	//添加使用BeanDefinition方式进行属性注入
	public void setBeanDefinitionPropertyValuesBeanTest(BeanDefinitionPropertyValuesBeanTest beanDefinitionPropertyValuesBeanTest){
		System.out.println("BeanDefinitionPropertyValuesBeanTest=[{}]"+beanDefinitionPropertyValuesBeanTest);
	}
	
 
	//用来打印@Autowired作用在属性上进行注入是否成功
	public void printf(){
		System.out.println("autowiredFiledBeanTest=[{}]"+autowiredFiledBeanTest);
	}
 
}

Class clazz = null;
Field autowiredFiledBeanTest = clazz.getDeclaredField("autowiredFiledBeanTest");
autowiredFiledBeanTest.setAccessible(true);
autowiredFiledBeanTest.set(this,getBean(AnnotationAutowiredFiledBeanTest.class));

BeanInfo beanInfo = Introspector.getBeanInfo(SpringBeanInfoTest.class);
PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();
 
for (PropertyDescriptor propertyDescriptor : propertyDescriptors) {
	Method writeMethod = propertyDescriptor.getWriteMethod();
	writeMethod.invoke(this,getBean(parma))
}

//先从容器中获取bean，有则直接返回进行注入
	//无则调用createBean创建需要进行注入的bean，放进单例池，最后再进行注入
	protected void populateBean(String beanName, RootBeanDefinition mbd, @Nullable BeanWrapper bw) {
		if (bw == null) {
			if (mbd.hasPropertyValues()) {
				throw new BeanCreationException(
						mbd.getResourceDescription(), beanName, "Cannot apply property values to null instance");
			}
			else {
				// Skip property population phase for null instance.
				return;
			}
		}
 
		// Give any InstantiationAwareBeanPostProcessors the opportUnity to modify the
		// state of the bean before properties are set. This can be used, for example,
		// to support styles of field injection.
		if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {
			for (BeanPostProcessor bp : getBeanPostProcessors()) {
				if (bp instanceof InstantiationAwareBeanPostProcessor) {
					InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
					if (!ibp.postProcessAfterInstantiation(bw.getWrappedInstance(), beanName)) {
						return;
					}
				}
			}
		}
 
		//1、获取到MutablePropertyValues对象，里面的List<PropertyValue> propertyValueList封装着一些属性的定义
		//这里现在只能获取到手动使用BeanDefinition动态添加的属性
		PropertyValues pvs = (mbd.hasPropertyValues() ? mbd.getPropertyValues() : null);
 
		//获取注入模型
		int resolvedAutowireMode = mbd.getResolvedAutowireMode();
		//2、注入模型为1或者2（自动注入），通过内省机制获取所有符合的属性（包括获取到使用了@Autowired注解的set），并getbean放进propertyValueList中
		if (resolvedAutowireMode == AUTOWIRE_BY_NAME || resolvedAutowireMode == AUTOWIRE_BY_TYPE) {
			MutablePropertyValues newPvs = new MutablePropertyValues(pvs);
			// Add property values based on autowire by name if applicable.
			//获取到符合规则的属性（setter）
			//然后获取到该属性的bean，并加入到MutablePropertyValues中的List中
			if (resolvedAutowireMode == AUTOWIRE_BY_NAME) {
				autowireByName(beanName, mbd, bw, newPvs);
			}
			// Add property values based on autowire by type if applicable.
			//获取到符合规则的属性（setter）
			// 然后获取到该属性的bean，并加入到MutablePropertyValues中的List中
			if (resolvedAutowireMode == AUTOWIRE_BY_TYPE) {
				autowireByType(beanName, mbd, bw, newPvs);
			}
			//所有符合上面的属性都会加到这里
			pvs = newPvs;
		}
 
		boolean hasInstAwareBpps = hasInstantiationAwareBeanPostProcessors();
		boolean needsDepCheck = (mbd.getDependencyCheck() != AbstractBeanDefinition.DEPENDENCY_CHECK_NONE);
 
		//3、如果注入模型为0，手动注入，此时这里的propertyValueList只会存在我们手动使用BeanDefinition add进去的。
		//那么到这里为止所有set方法都没被识别到（既不会在applyPropertyValues中执行了）
		//下面的循环则是去解析@Autowired作用的属性、方法（反射机制）
		//注意：如果该属性已经存在propertyValueList，这里则不会对其进行解析（即自动注入模型下@Autowired作用在方法的被忽略执行）
		PropertyDescriptor[] filteredPds = null;
		if (hasInstAwareBpps) {
			if (pvs == null) {
				pvs = mbd.getPropertyValues();
			}
 
			//获取到所有BeanPostProcessor
			//如果是InstantiationAwareBeanPostProcessor，即处理@Autowired注解、@Resouce注解、@PostConstruct注解的BeanPostProcessor类型，则完成注入等操作
			for (BeanPostProcessor bp : getBeanPostProcessors()) {
				//完成@Autowired作用在属性、方法上面的处理（使用反射）
				if (bp instanceof InstantiationAwareBeanPostProcessor) {
					InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
					//完成@Autowired作用在属性、方法上面的处理
					PropertyValues pvsToUse = ibp.postProcessProperties(pvs, bw.getWrappedInstance(), beanName);
					if (pvsToUse == null) {
						if (filteredPds == null) {
							filteredPds = filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching);
						}
						pvsToUse = ibp.postProcessPropertyValues(pvs, filteredPds, bw.getWrappedInstance(), beanName);
						if (pvsToUse == null) {
							return;
						}
					}
					pvs = pvsToUse;
				}
			}
		}
		if (needsDepCheck) {
			if (filteredPds == null) {
				filteredPds = filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching);
			}
			checkDependencies(beanName, mbd, filteredPds, pvs);
		}
 
		//4、处理propertyValueList中的所有还未执行的属性
		//遍历属性名、对象，内省机制调用invoke方法执行set方法等
		if (pvs != null) {
			applyPropertyValues(beanName, mbd, bw, pvs);
		}
	}