springboot InstantiationAwareBeanPostProcessor说明

矫情吗；* 2022-09-03 01:23 106阅读 0赞

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## springboot InstantiationAwareBeanPostProcessor说明 ##

## \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* ##

**相关类与接口**

**InstantiationAwareBeanPostProcessor**

public interface InstantiationAwareBeanPostProcessor extends BeanPostProcessor {
        @Nullable
        default Object postProcessBeforeInstantiation(Class<?> beanClass, String beanName) throws BeansException {
            return null;
        }
    
        default boolean postProcessAfterInstantiation(Object bean, String beanName) throws BeansException {
            return true;
        }
    
        @Nullable
        default PropertyValues postProcessProperties(PropertyValues pvs, Object bean, String beanName) throws BeansException {
            return null;
        }
    
        /** @deprecated */
        @Deprecated
        @Nullable
        default PropertyValues postProcessPropertyValues(PropertyValues pvs, PropertyDescriptor[] pds, Object bean, String beanName) throws BeansException {
            return pvs;
        }
    }

**BeanPostProcessor**

public interface BeanPostProcessor {
        @Nullable
        default Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
            return bean;
        }
    
        @Nullable
        default Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
            return bean;
        }
    }

**CommonAnnotationBeanPostProcessor：@PostProcessor、@PreDestroy、@Resource**

public class CommonAnnotationBeanPostProcessor extends InitDestroyAnnotationBeanPostProcessor implements InstantiationAwareBeanPostProcessor, BeanFactoryAware, Serializable {
        @Nullable
        private static final Class<? extends Annotation> webServiceRefClass = loadAnnotationType("javax.xml.ws.WebServiceRef");
        @Nullable
        private static final Class<? extends Annotation> ejbClass = loadAnnotationType("javax.ejb.EJB");
        private static final Set<Class<? extends Annotation>> resourceAnnotationTypes = new LinkedHashSet(4);
        private final Set<String> ignoredResourceTypes = new HashSet(1);
        private boolean fallbackToDefaultTypeMatch = true;
        private boolean alwaysUseJndiLookup = false;
        private transient BeanFactory jndiFactory = new SimpleJndiBeanFactory();
        @Nullable
        private transient BeanFactory resourceFactory;
        @Nullable
        private transient BeanFactory beanFactory;
        @Nullable
        private transient StringValueResolver embeddedValueResolver;
        private final transient Map<String, InjectionMetadata> injectionMetadataCache = new ConcurrentHashMap(256);
    
        public CommonAnnotationBeanPostProcessor() {
            this.setOrder(2147483644);
            this.setInitAnnotationType(PostConstruct.class);     //初始化注解：PostConstruct
            this.setDestroyAnnotationType(PreDestroy.class);     //销毁注解：PreDestroy
            this.ignoreResourceType("javax.xml.ws.WebServiceContext");
        }
    
        public void ignoreResourceType(String resourceType) {
        public void setFallbackToDefaultTypeMatch(boolean fallbackToDefaultTypeMatch) {
        public void setAlwaysUseJndiLookup(boolean alwaysUseJndiLookup) {
        public void setJndiFactory(BeanFactory jndiFactory) {
        public void setResourceFactory(BeanFactory resourceFactory) {
        public void setBeanFactory(BeanFactory beanFactory) {
    
    
        public void postProcessMergedBeanDefinition(RootBeanDefinition beanDefinition, Class<?> beanType, String beanName) {
        public void resetBeanDefinition(String beanName) {
    
    
        public Object postProcessBeforeInstantiation(Class<?> beanClass, String beanName) {
            return null;
        }  //实例化之前不做处理
    
        public boolean postProcessAfterInstantiation(Object bean, String beanName) {
            return true;
        }  //属性填充时，使用postProcessProperties返回的PropertyValues
    
        public PropertyValues postProcessProperties(PropertyValues pvs, Object bean, String beanName) {
            InjectionMetadata metadata = this.findResourceMetadata(beanName, bean.getClass(), pvs);
    
            try {
                metadata.inject(bean, beanName, pvs);
                return pvs;
            } catch (Throwable var6) {
                throw new BeanCreationException(beanName, "Injection of resource dependencies failed", var6);
            }
        }
    
        /** @deprecated */
        @Deprecated
        public PropertyValues postProcessPropertyValues(PropertyValues pvs, PropertyDescriptor[] pds, Object bean, String beanName) {
            return this.postProcessProperties(pvs, bean, beanName);
        }
    
    
        private InjectionMetadata findResourceMetadata(String beanName, Class<?> clazz, @Nullable PropertyValues pvs) {
        private InjectionMetadata buildResourceMetadata(Class<?> clazz) {
    
        protected Object buildLazyResourceProxy(final CommonAnnotationBeanPostProcessor.LookupElement element, @Nullable final String requestingBeanName) {
    
        protected Object getResource(CommonAnnotationBeanPostProcessor.LookupElement element, @Nullable String requestingBeanName) throws NoSuchBeanDefinitionException {
        protected Object autowireResource(BeanFactory factory, CommonAnnotationBeanPostProcessor.LookupElement element, @Nullable String requestingBeanName) throws NoSuchBeanDefinitionException {
    
    
        @Nullable
        private static Class<? extends Annotation> loadAnnotationType(String name) {
            try {
                return ClassUtils.forName(name, CommonAnnotationBeanPostProcessor.class.getClassLoader());
            } catch (ClassNotFoundException var2) {
                return null;
            }
        }
    
    
        static {
            resourceAnnotationTypes.add(Resource.class);  //静态语句块中添加注解：Resource
            if (webServiceRefClass != null) {             //如果类加载器中有注解：javax.xml.ws.WebServiceRef，则加入注解WebServiceRefClass
                resourceAnnotationTypes.add(webServiceRefClass);
            }
    
            if (ejbClass != null) {                       //如果类加载器中有注解：javax.ejb.EJB，则加入注解EJB
                resourceAnnotationTypes.add(ejbClass);
            }
    
        }   
    
    
    ************
    内部类：LookupDependencyDescriptor
    
        private static class LookupDependencyDescriptor extends DependencyDescriptor {
            private final Class<?> lookupType;
    
            public LookupDependencyDescriptor(Field field, Class<?> lookupType) {
            public LookupDependencyDescriptor(Method method, Class<?> lookupType) {
    
            public Class<?> getDependencyType() {
                return this.lookupType;
            }
        }
    
    
    
    ************
    内部类：EjbRefElement
    
        private class EjbRefElement extends CommonAnnotationBeanPostProcessor.LookupElement {
            private final String beanName;
    
            public EjbRefElement(Member member, AnnotatedElement ae, @Nullable PropertyDescriptor pd) {
    
            protected Object getResourceToInject(Object target, @Nullable String requestingBeanName) {
    
    
    ************
    内部类：WebServiceRefElement
    
        private class WebServiceRefElement extends CommonAnnotationBeanPostProcessor.LookupElement {
            private final Class<?> elementType;
            private final String wsdlLocation;
    
            public WebServiceRefElement(Member member, AnnotatedElement ae, @Nullable PropertyDescriptor pd) {
    
            protected Object getResourceToInject(Object target, @Nullable String requestingBeanName) {
    
    
    ************
    内部类：ResourceElement
    
        private class ResourceElement extends CommonAnnotationBeanPostProcessor.LookupElement {
            private final boolean lazyLookup;
    
            public ResourceElement(Member member, AnnotatedElement ae, @Nullable PropertyDescriptor pd) {
    
            protected Object getResourceToInject(Object target, @Nullable String requestingBeanName) {
    
    
    ************
    内部类：LookupElement
    
        protected abstract static class LookupElement extends InjectedElement {
            protected String name = "";
            protected boolean isDefaultName = false;
            protected Class<?> lookupType = Object.class;
            @Nullable
            protected String mappedName;
    
            public LookupElement(Member member, @Nullable PropertyDescriptor pd) {
    
    
            public final String getName() {
            public final Class<?> getLookupType() {
    
            public final DependencyDescriptor getDependencyDescriptor() {

**InitDestroyAnnotationBeanPostProcessor：初始化、销毁处理器**

public class InitDestroyAnnotationBeanPostProcessor implements DestructionAwareBeanPostProcessor, MergedBeanDefinitionPostProcessor, PriorityOrdered, Serializable {
    
        private final transient InitDestroyAnnotationBeanPostProcessor.LifecycleMetadata emptyLifecycleMetadata = new InitDestroyAnnotationBeanPostProcessor.LifecycleMetadata(Object.class, Collections.emptyList(), Collections.emptyList()) {
            public void checkConfigMembers(RootBeanDefinition beanDefinition) {
            }
    
            public void invokeInitMethods(Object target, String beanName) {
            }
    
            public void invokeDestroyMethods(Object target, String beanName) {
            }
    
            public boolean hasDestroyMethods() {
                return false;
            }
        };
        protected transient Log logger = LogFactory.getLog(this.getClass());
    
        @Nullable
        private Class<? extends Annotation> initAnnotationType;    //初始化注解
        @Nullable
        private Class<? extends Annotation> destroyAnnotationType; //销毁注解
        private int order = 2147483647;
        @Nullable
        private final transient Map<Class<?>, InitDestroyAnnotationBeanPostProcessor.LifecycleMetadata> lifecycleMetadataCache = new ConcurrentHashMap(256);
    
        public InitDestroyAnnotationBeanPostProcessor() {
        }
    
        public void setInitAnnotationType(Class<? extends Annotation> initAnnotationType) {
        public void setDestroyAnnotationType(Class<? extends Annotation> destroyAnnotationType) {
    
        public void setOrder(int order) {
        public int getOrder() {
    
        public void postProcessMergedBeanDefinition(RootBeanDefinition beanDefinition, Class<?> beanType, String beanName) {
            InitDestroyAnnotationBeanPostProcessor.LifecycleMetadata metadata = this.findLifecycleMetadata(beanType);
            metadata.checkConfigMembers(beanDefinition);
        }
    
        public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
            InitDestroyAnnotationBeanPostProcessor.LifecycleMetadata metadata = this.findLifecycleMetadata(bean.getClass());
    
            try {
                metadata.invokeInitMethods(bean, beanName);
                return bean;
            } catch (InvocationTargetException var5) {
                throw new BeanCreationException(beanName, "Invocation of init method failed", var5.getTargetException());
            } catch (Throwable var6) {
                throw new BeanCreationException(beanName, "Failed to invoke init method", var6);
            }
        }
    
        public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
            return bean;
        }
    
        public void postProcessBeforeDestruction(Object bean, String beanName) throws BeansException {
            InitDestroyAnnotationBeanPostProcessor.LifecycleMetadata metadata = this.findLifecycleMetadata(bean.getClass());
    
            try {
                metadata.invokeDestroyMethods(bean, beanName);
            } catch (InvocationTargetException var6) {
                String msg = "Destroy method on bean with name '" + beanName + "' threw an exception";
                if (this.logger.isDebugEnabled()) {
                    this.logger.warn(msg, var6.getTargetException());
                } else {
                    this.logger.warn(msg + ": " + var6.getTargetException());
                }
            } catch (Throwable var7) {
                this.logger.warn("Failed to invoke destroy method on bean with name '" + beanName + "'", var7);
            }
    
        }
    
        public boolean requiresDestruction(Object bean) {
            return this.findLifecycleMetadata(bean.getClass()).hasDestroyMethods();
        }
    
        private InitDestroyAnnotationBeanPostProcessor.LifecycleMetadata findLifecycleMetadata(Class<?> clazz) {
        private InitDestroyAnnotationBeanPostProcessor.LifecycleMetadata buildLifecycleMetadata(Class<?> clazz) {
    
        private void readObject(ObjectInputStream ois) throws IOException, ClassNotFoundException {
    
    
    **************
    内部类：LifecycleElement
    
        private static class LifecycleElement {
            private final Method method;
            private final String identifier;
    
            public LifecycleElement(Method method) {
    
    
            public Method getMethod() {
            public String getIdentifier() {
    
            public void invoke(Object target) throws Throwable {
    
            public boolean equals(@Nullable Object other) {
            public int hashCode() {
    
    
    **************
    内部类：LifecycleMetadata
    
        private class LifecycleMetadata {
            private final Class<?> targetClass;
            private final Collection<InitDestroyAnnotationBeanPostProcessor.LifecycleElement> initMethods;
                                  //初始化方法，可为多个
            private final Collection<InitDestroyAnnotationBeanPostProcessor.LifecycleElement> destroyMethods;
                                  //销毁方法，可为多个
            @Nullable
            private volatile Set<InitDestroyAnnotationBeanPostProcessor.LifecycleElement> checkedInitMethods;
            @Nullable
            private volatile Set<InitDestroyAnnotationBeanPostProcessor.LifecycleElement> checkedDestroyMethods;
    
            public LifecycleMetadata(Class<?> targetClass, Collection<InitDestroyAnnotationBeanPostProcessor.LifecycleElement> initMethods, Collection<InitDestroyAnnotationBeanPostProcessor.LifecycleElement> destroyMethods) {
    
            public void checkConfigMembers(RootBeanDefinition beanDefinition) {
    
            public void invokeInitMethods(Object target, String beanName) throws Throwable {
                Collection<InitDestroyAnnotationBeanPostProcessor.LifecycleElement> checkedInitMethods = this.checkedInitMethods;
                Collection<InitDestroyAnnotationBeanPostProcessor.LifecycleElement> initMethodsToIterate = checkedInitMethods != null ? checkedInitMethods : this.initMethods;
                InitDestroyAnnotationBeanPostProcessor.LifecycleElement element;
                if (!((Collection)initMethodsToIterate).isEmpty()) {
                    for(Iterator var5 = ((Collection)initMethodsToIterate).iterator(); var5.hasNext(); element.invoke(target)) {
                            //调用注解的初始化方法
                        element = (InitDestroyAnnotationBeanPostProcessor.LifecycleElement)var5.next();
                        if (InitDestroyAnnotationBeanPostProcessor.this.logger.isTraceEnabled()) {
                            InitDestroyAnnotationBeanPostProcessor.this.logger.trace("Invoking init method on bean '" + beanName + "': " + element.getMethod());
                        }
                    }
                }
    
            }
    
            public void invokeDestroyMethods(Object target, String beanName) throws Throwable {
                Collection<InitDestroyAnnotationBeanPostProcessor.LifecycleElement> checkedDestroyMethods = this.checkedDestroyMethods;
                Collection<InitDestroyAnnotationBeanPostProcessor.LifecycleElement> destroyMethodsToUse = checkedDestroyMethods != null ? checkedDestroyMethods : this.destroyMethods;
                InitDestroyAnnotationBeanPostProcessor.LifecycleElement element;
                if (!((Collection)destroyMethodsToUse).isEmpty()) {
                    for(Iterator var5 = ((Collection)destroyMethodsToUse).iterator(); var5.hasNext(); element.invoke(target)) {
                            //调用注解的销毁方法
                        element = (InitDestroyAnnotationBeanPostProcessor.LifecycleElement)var5.next();
                        if (InitDestroyAnnotationBeanPostProcessor.this.logger.isTraceEnabled()) {
                            InitDestroyAnnotationBeanPostProcessor.this.logger.trace("Invoking destroy method on bean '" + beanName + "': " + element.getMethod());
                        }
                    }
                }
    
            }
    
            public boolean hasDestroyMethods() {

**DestructionAwareBeanPostProcessor：销毁接口**

public interface DestructionAwareBeanPostProcessor extends BeanPostProcessor {
        void postProcessBeforeDestruction(Object var1, String var2) throws BeansException;
    
        default boolean requiresDestruction(Object bean) {
            return true;
        }
    }

**AutowiredAnnotationBeanPostProcessor：@Autowired、@Value、@Inject**

public class AutowiredAnnotationBeanPostProcessor implements SmartInstantiationAwareBeanPostProcessor, MergedBeanDefinitionPostProcessor, PriorityOrdered, BeanFactoryAware {
        protected final Log logger = LogFactory.getLog(this.getClass());
        private final Set<Class<? extends Annotation>> autowiredAnnotationTypes = new LinkedHashSet(4);
    
        private String requiredParameterName = "required";
        private boolean requiredParameterValue = true;       //是否需要参数值，默认为true
        private int order = 2147483645;
    
        @Nullable
        private ConfigurableListableBeanFactory beanFactory;
        private final Set<String> lookupMethodsChecked = Collections.newSetFromMap(new ConcurrentHashMap(256));
        private final Map<Class<?>, Constructor<?>[]> candidateConstructorsCache = new ConcurrentHashMap(256);
        private final Map<String, InjectionMetadata> injectionMetadataCache = new ConcurrentHashMap(256);
    
        public AutowiredAnnotationBeanPostProcessor() {
            this.autowiredAnnotationTypes.add(Autowired.class);  //添加注解：Autowired
            this.autowiredAnnotationTypes.add(Value.class);      //添加注解：Value
    
            try {
                this.autowiredAnnotationTypes.add(ClassUtils.forName("javax.inject.Inject", AutowiredAnnotationBeanPostProcessor.class.getClassLoader()));
                                              //如果类加载器有javax.inject.Inject，则添加注解Inject
                this.logger.trace("JSR-330 'javax.inject.Inject' annotation found and supported for autowiring");
            } catch (ClassNotFoundException var2) {
            }
    
        }
    
        public void setAutowiredAnnotationType(Class<? extends Annotation> autowiredAnnotationType) {
        public void setAutowiredAnnotationTypes(Set<Class<? extends Annotation>> autowiredAnnotationTypes) {
    
        public void setRequiredParameterName(String requiredParameterName) {
        public void setRequiredParameterValue(boolean requiredParameterValue) {
    
        public void setOrder(int order) {
        public int getOrder() {
    
        public void setBeanFactory(BeanFactory beanFactory) {
    
        public void postProcessMergedBeanDefinition(RootBeanDefinition beanDefinition, Class<?> beanType, String beanName) {
            InjectionMetadata metadata = this.findAutowiringMetadata(beanName, beanType, (PropertyValues)null);
            metadata.checkConfigMembers(beanDefinition);
        }
    
        public void resetBeanDefinition(String beanName) {
            this.lookupMethodsChecked.remove(beanName);
            this.injectionMetadataCache.remove(beanName);
        }
    
        @Nullable
        public Constructor<?>[] determineCandidateConstructors(Class<?> beanClass, String beanName) throws BeanCreationException {
    
    
        public PropertyValues postProcessProperties(PropertyValues pvs, Object bean, String beanName) {
            InjectionMetadata metadata = this.findAutowiringMetadata(beanName, bean.getClass(), pvs);
    
            try {
                metadata.inject(bean, beanName, pvs);
                return pvs;
            } catch (BeanCreationException var6) {
                throw var6;
            } catch (Throwable var7) {
                throw new BeanCreationException(beanName, "Injection of autowired dependencies failed", var7);
            }
        }
    
        public void processInjection(Object bean) throws BeanCreationException {
    
        private InjectionMetadata findAutowiringMetadata(String beanName, Class<?> clazz, @Nullable PropertyValues pvs) {
        private InjectionMetadata buildAutowiringMetadata(Class<?> clazz) {
        private MergedAnnotation<?> findAutowiredAnnotation(AccessibleObject ao) {
    
    
        protected boolean determineRequiredStatus(MergedAnnotation<?> ann) {
        protected <T> Map<String, T> findAutowireCandidates(Class<T> type) throws BeansException {
    
        private void registerDependentBeans(@Nullable String beanName, Set<String> autowiredBeanNames) {
        private Object resolvedCachedArgument(@Nullable String beanName, @Nullable Object cachedArgument) {
    
    
    ***********
    内部类：ShortcutDependencyDescriptor
    
        private static class ShortcutDependencyDescriptor extends DependencyDescriptor {
            private final String shortcut;
            private final Class<?> requiredType;
    
            public ShortcutDependencyDescriptor(DependencyDescriptor original, String shortcut, Class<?> requiredType) {
    
            public Object resolveShortcut(BeanFactory beanFactory) {
    
    
    ***********
    内部类：AutowiredMethodElement
    
        private class AutowiredMethodElement extends InjectedElement {
            private final boolean required;
            private volatile boolean cached;
            @Nullable
            private volatile Object[] cachedMethodArguments;
    
            public AutowiredMethodElement(Method method, boolean required, @Nullable PropertyDescriptor pd) {
    
            protected void inject(Object bean, @Nullable String beanName, @Nullable PropertyValues pvs) throws Throwable {
    
            private Object[] resolveCachedArguments(@Nullable String beanName) {
            private Object[] resolveMethodArguments(Method method, Object bean, @Nullable String beanName) {
    
    
    ***********
    内部类：AutowiredFieldElement
    
        private class AutowiredFieldElement extends InjectedElement {
            private final boolean required;
            private volatile boolean cached;
            @Nullable
            private volatile Object cachedFieldValue;
    
            public AutowiredFieldElement(Field field, boolean required) {
    
            protected void inject(Object bean, @Nullable String beanName, @Nullable PropertyValues pvs) throws Throwable {
    
            private Object resolveFieldValue(Field field, Object bean, @Nullable String beanName) {

**SmartInstantiationAwareBeanPostProcessor**

public interface SmartInstantiationAwareBeanPostProcessor extends InstantiationAwareBeanPostProcessor {
        @Nullable
        default Class<?> predictBeanType(Class<?> beanClass, String beanName) throws BeansException {
            return null;
        }
    
        @Nullable
        default Constructor<?>[] determineCandidateConstructors(Class<?> beanClass, String beanName) throws BeansException {
            return null;
        }
    
        default Object getEarlyBeanReference(Object bean, String beanName) throws BeansException {
            return bean;
        }
    }

**MergedBeanDefinitionPostProcessor**

public interface MergedBeanDefinitionPostProcessor extends BeanPostProcessor {
        void postProcessMergedBeanDefinition(RootBeanDefinition var1, Class<?> var2, String var3);
    
        default void resetBeanDefinition(String beanName) {
        }
    }

**AbstractAutowireCapableBeanFactory**

public abstract class AbstractAutowireCapableBeanFactory extends AbstractBeanFactory implements AutowireCapableBeanFactory {
    
    
    *********
    createBean
    
        protected Object createBean(String beanName, RootBeanDefinition mbd, @Nullable Object[] args) throws BeanCreationException {
            if (this.logger.isTraceEnabled()) {
                this.logger.trace("Creating instance of bean '" + beanName + "'");
            }
    
            RootBeanDefinition mbdToUse = mbd;
            Class<?> resolvedClass = this.resolveBeanClass(mbd, beanName, new Class[0]);
            if (resolvedClass != null && !mbd.hasBeanClass() && mbd.getBeanClassName() != null) {
                mbdToUse = new RootBeanDefinition(mbd);
                mbdToUse.setBeanClass(resolvedClass);
            }
    
            try {
                mbdToUse.prepareMethodOverrides();
            } catch (BeanDefinitionValidationException var9) {
                throw new BeanDefinitionStoreException(mbdToUse.getResourceDescription(), beanName, "Validation of method overrides failed", var9);
            }
    
            Object beanInstance;
            try {
                beanInstance = this.resolveBeforeInstantiation(beanName, mbdToUse);
                               //实例化之前解析
                if (beanInstance != null) {
                    return beanInstance;
                }
            } catch (Throwable var10) {
                throw new BeanCreationException(mbdToUse.getResourceDescription(), beanName, "BeanPostProcessor before instantiation of bean failed", var10);
            }
    
            try {
                beanInstance = this.doCreateBean(beanName, mbdToUse, args);
                if (this.logger.isTraceEnabled()) {
                    this.logger.trace("Finished creating instance of bean '" + beanName + "'");
                }
    
                return beanInstance;
            } catch (ImplicitlyAppearedSingletonException | BeanCreationException var7) {
                throw var7;
            } catch (Throwable var8) {
                throw new BeanCreationException(mbdToUse.getResourceDescription(), beanName, "Unexpected exception during bean creation", var8);
            }
        }
    
    
    
        @Nullable
        protected Object resolveBeforeInstantiation(String beanName, RootBeanDefinition mbd) {
                         //实例化之前解析
            Object bean = null;
            if (!Boolean.FALSE.equals(mbd.beforeInstantiationResolved)) {
                if (!mbd.isSynthetic() && this.hasInstantiationAwareBeanPostProcessors()) {
                                    
                    Class<?> targetType = this.determineTargetType(beanName, mbd);
                    if (targetType != null) {
                                   //判断targetType是否有InstantiationAwareBeanPostProcessor，
                                   //如果有，则调用postProcessBeforeInstantiation方法
                        bean = this.applyBeanPostProcessorsBeforeInstantiation(targetType, beanName);
                        if (bean != null) {
                            bean = this.applyBeanPostProcessorsAfterInitialization(bean, beanName);
                        }  //如果bean不为null，调用postProcessAfterInitialization
                    }
                }
    
                mbd.beforeInstantiationResolved = bean != null;
            }
    
            return bean;
        }
    
        @Nullable
        protected Object applyBeanPostProcessorsBeforeInstantiation(Class<?> beanClass, String beanName) {
            Iterator var3 = this.getBeanPostProcessorCache().instantiationAware.iterator();
    
            Object result;
            do {
                if (!var3.hasNext()) {
                    return null;
                }
    
                InstantiationAwareBeanPostProcessor bp = (InstantiationAwareBeanPostProcessor)var3.next();
                result = bp.postProcessBeforeInstantiation(beanClass, beanName);
                            //调用postProcessBeforeInstantiation
            } while(result == null);
    
            return result;
        }
    
        public Object applyBeanPostProcessorsAfterInitialization(Object existingBean, String beanName) throws BeansException {
            Object result = existingBean;
    
            Object current;
            for(Iterator var4 = this.getBeanPostProcessors().iterator(); var4.hasNext(); result = current) {
                BeanPostProcessor processor = (BeanPostProcessor)var4.next();
                current = processor.postProcessAfterInitialization(result, beanName);
                                    //调用postProcessAfterInitialization方法
                if (current == null) {
                    return result;
                }
            }
    
            return result;
        }
    
    
    
        protected Object doCreateBean(String beanName, RootBeanDefinition mbd, @Nullable Object[] args) throws BeanCreationException {
            BeanWrapper instanceWrapper = null;
            if (mbd.isSingleton()) {
                instanceWrapper = (BeanWrapper)this.factoryBeanInstanceCache.remove(beanName);
            }
    
            if (instanceWrapper == null) {
                instanceWrapper = this.createBeanInstance(beanName, mbd, args);
            }   //创建bean实例
    
            Object bean = instanceWrapper.getWrappedInstance();
            Class<?> beanType = instanceWrapper.getWrappedClass();
            if (beanType != NullBean.class) {
                mbd.resolvedTargetType = beanType;
            }
    
            synchronized(mbd.postProcessingLock) {
                if (!mbd.postProcessed) {
                    try {
                        this.applyMergedBeanDefinitionPostProcessors(mbd, beanType, beanName);
                    } catch (Throwable var17) {
                        throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Post-processing of merged bean definition failed", var17);
                    }
    
                    mbd.postProcessed = true;
                }
            }
    
            boolean earlySingletonExposure = mbd.isSingleton() && this.allowCircularReferences && this.isSingletonCurrentlyInCreation(beanName);
            if (earlySingletonExposure) {
                if (this.logger.isTraceEnabled()) {
                    this.logger.trace("Eagerly caching bean '" + beanName + "' to allow for resolving potential circular references");
                }
    
                this.addSingletonFactory(beanName, () -> {
                    return this.getEarlyBeanReference(beanName, mbd, bean);
                });
            }
    
            Object exposedObject = bean;
    
            try {
                this.populateBean(beanName, mbd, instanceWrapper);                  //属性填充
                exposedObject = this.initializeBean(beanName, exposedObject, mbd);  //初始化
            } catch (Throwable var18) {
                if (var18 instanceof BeanCreationException && beanName.equals(((BeanCreationException)var18).getBeanName())) {
                    throw (BeanCreationException)var18;
                }
    
                throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Initialization of bean failed", var18);
            }
    
            if (earlySingletonExposure) {
                Object earlySingletonReference = this.getSingleton(beanName, false);
                if (earlySingletonReference != null) {
                    if (exposedObject == bean) {
                        exposedObject = earlySingletonReference;
                    } else if (!this.allowRawInjectionDespiteWrapping && this.hasDependentBean(beanName)) {
                        String[] dependentBeans = this.getDependentBeans(beanName);
                        Set<String> actualDependentBeans = new LinkedHashSet(dependentBeans.length);
                        String[] var12 = dependentBeans;
                        int var13 = dependentBeans.length;
    
                        for(int var14 = 0; var14 < var13; ++var14) {
                            String dependentBean = var12[var14];
                            if (!this.removeSingletonIfCreatedForTypeCheckOnly(dependentBean)) {
                                actualDependentBeans.add(dependentBean);
                            }
                        }
    
                        if (!actualDependentBeans.isEmpty()) {
                            throw new BeanCurrentlyInCreationException(beanName, "Bean with name '" + beanName + "' has been injected into other beans [" + StringUtils.collectionToCommaDelimitedString(actualDependentBeans) + "] in its raw version as part of a circular reference, but has eventually been wrapped. This means that said other beans do not use the final version of the bean. This is often the result of over-eager type matching - consider using 'getBeanNamesForType' with the 'allowEagerInit' flag turned off, for example.");
                        }
                    }
                }
            }
    
            try {
                this.registerDisposableBeanIfNecessary(beanName, bean, mbd);
                return exposedObject;
            } catch (BeanDefinitionValidationException var16) {
                throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Invalid destruction signature", var16);
            }
        }
    
    
    *************
    属性填充
    
        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 {
                if (!mbd.isSynthetic() && this.hasInstantiationAwareBeanPostProcessors()) {
                    Iterator var4 = this.getBeanPostProcessorCache().instantiationAware.iterator();
    
                    while(var4.hasNext()) {
                        InstantiationAwareBeanPostProcessor bp = (InstantiationAwareBeanPostProcessor)var4.next();
                        if (!bp.postProcessAfterInstantiation(bw.getWrappedInstance(), beanName)) {
                            return;
                        }
                    }
                }
    
                PropertyValues pvs = mbd.hasPropertyValues() ? mbd.getPropertyValues() : null;
                int resolvedAutowireMode = mbd.getResolvedAutowireMode();
                if (resolvedAutowireMode == 1 || resolvedAutowireMode == 2) {
                    MutablePropertyValues newPvs = new MutablePropertyValues((PropertyValues)pvs);
                    if (resolvedAutowireMode == 1) {
                        this.autowireByName(beanName, mbd, bw, newPvs);
                    }
    
                    if (resolvedAutowireMode == 2) {
                        this.autowireByType(beanName, mbd, bw, newPvs);
                    }
    
                    pvs = newPvs;
                }
    
                boolean hasInstAwareBpps = this.hasInstantiationAwareBeanPostProcessors();
                boolean needsDepCheck = mbd.getDependencyCheck() != 0;
                PropertyDescriptor[] filteredPds = null;
                if (hasInstAwareBpps) {
                    if (pvs == null) {
                        pvs = mbd.getPropertyValues();
                    }
    
                    PropertyValues pvsToUse;
                    for(Iterator var9 = this.getBeanPostProcessorCache().instantiationAware.iterator(); var9.hasNext(); pvs = pvsToUse) {                    
                        InstantiationAwareBeanPostProcessor bp = (InstantiationAwareBeanPostProcessor)var9.next();
                        pvsToUse = bp.postProcessProperties((PropertyValues)pvs, bw.getWrappedInstance(), beanName);
                            //InstantiationAwareBeanPostProcessor返回的PropertyValues
                            //pvs = pvsToUse，待注入的属性值
    
                        if (pvsToUse == null) {
                            if (filteredPds == null) {
                                filteredPds = this.filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching);
                            }
    
                            pvsToUse = bp.postProcessPropertyValues((PropertyValues)pvs, filteredPds, bw.getWrappedInstance(), beanName);
                            if (pvsToUse == null) {
                                return;
                            }
                        }
                    }
                }
    
                if (needsDepCheck) {
                    if (filteredPds == null) {
                        filteredPds = this.filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching);
                    }
    
                    this.checkDependencies(beanName, mbd, filteredPds, (PropertyValues)pvs);
                }
    
                if (pvs != null) {
                    this.applyPropertyValues(beanName, mbd, bw, (PropertyValues)pvs);
                }   //如果pvs不为空则注入属性值
    
            }
        }
    
    
    
    *************
    初始化
    
        protected Object initializeBean(String beanName, Object bean, @Nullable RootBeanDefinition mbd) {
            if (System.getSecurityManager() != null) {
                AccessController.doPrivileged(() -> {
                    this.invokeAwareMethods(beanName, bean);
                    return null;
                }, this.getAccessControlContext());
            } else {
                this.invokeAwareMethods(beanName, bean);
            }  //调用aware方法（BeanNameAware、BeanClassLoaderAware、BeanFactoryAware）
    
            Object wrappedBean = bean;
            if (mbd == null || !mbd.isSynthetic()) {
                wrappedBean = this.applyBeanPostProcessorsBeforeInitialization(bean, beanName);
            }  //初始化前调用applyBeanPostProcessorsBeforeInitialization
    
            try {
                this.invokeInitMethods(beanName, wrappedBean, mbd);
                     //调用initMethod（InitializingBean、指定的initMethodName）
            } catch (Throwable var6) {
                throw new BeanCreationException(mbd != null ? mbd.getResourceDescription() : null, beanName, "Invocation of init method failed", var6);
            }
    
            if (mbd == null || !mbd.isSynthetic()) {
                wrappedBean = this.applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
            }        //调用applyBeanPostProcessorsAfterInitialization
    
            return wrappedBean;
        }
    
        private void invokeAwareMethods(String beanName, Object bean) {
            if (bean instanceof Aware) {
                if (bean instanceof BeanNameAware) {
                    ((BeanNameAware)bean).setBeanName(beanName);
                }
    
                if (bean instanceof BeanClassLoaderAware) {
                    ClassLoader bcl = this.getBeanClassLoader();
                    if (bcl != null) {
                        ((BeanClassLoaderAware)bean).setBeanClassLoader(bcl);
                    }
                }
    
                if (bean instanceof BeanFactoryAware) {
                    ((BeanFactoryAware)bean).setBeanFactory(this);
                }
            }
    
        }
    
        public Object applyBeanPostProcessorsBeforeInitialization(Object existingBean, String beanName) throws BeansException {
            Object result = existingBean;
    
            Object current;
            for(Iterator var4 = this.getBeanPostProcessors().iterator(); var4.hasNext(); result = current) {
                BeanPostProcessor processor = (BeanPostProcessor)var4.next();
                current = processor.postProcessBeforeInitialization(result, beanName);
                                   //调用postProcessBeforeInitialization
                if (current == null) {
                    return result;
                }
            }
    
            return result;
        }
    
        protected void invokeInitMethods(String beanName, Object bean, @Nullable RootBeanDefinition mbd) throws Throwable {
            boolean isInitializingBean = bean instanceof InitializingBean;
            if (isInitializingBean && (mbd == null || !mbd.isExternallyManagedInitMethod("afterPropertiesSet"))) {
                if (this.logger.isTraceEnabled()) {
                    this.logger.trace("Invoking afterPropertiesSet() on bean with name '" + beanName + "'");
                }
    
                if (System.getSecurityManager() != null) {
                    try {
                        AccessController.doPrivileged(() -> {
                            ((InitializingBean)bean).afterPropertiesSet();
                            return null;
                        }, this.getAccessControlContext());
                    } catch (PrivilegedActionException var6) {
                        throw var6.getException();
                    }
                } else {
                    ((InitializingBean)bean).afterPropertiesSet();
                }
            }
    
            if (mbd != null && bean.getClass() != NullBean.class) {
                String initMethodName = mbd.getInitMethodName();
                if (StringUtils.hasLength(initMethodName) && (!isInitializingBean || !"afterPropertiesSet".equals(initMethodName)) && !mbd.isExternallyManagedInitMethod(initMethodName)) {
                    this.invokeCustomInitMethod(beanName, bean, mbd);
                }
            }
    
        }
    
        protected void invokeCustomInitMethod(String beanName, Object bean, RootBeanDefinition mbd) throws Throwable {
            String initMethodName = mbd.getInitMethodName();
            Assert.state(initMethodName != null, "No init method set");
            Method initMethod = mbd.isNonPublicAccessAllowed() ? BeanUtils.findMethod(bean.getClass(), initMethodName, new Class[0]) : ClassUtils.getMethodIfAvailable(bean.getClass(), initMethodName, new Class[0]);
            if (initMethod == null) {
                if (mbd.isEnforceInitMethod()) {
                    throw new BeanDefinitionValidationException("Could not find an init method named '" + initMethodName + "' on bean with name '" + beanName + "'");
                } else {
                    if (this.logger.isTraceEnabled()) {
                        this.logger.trace("No default init method named '" + initMethodName + "' found on bean with name '" + beanName + "'");
                    }
    
                }
            } else {
                if (this.logger.isTraceEnabled()) {
                    this.logger.trace("Invoking init method  '" + initMethodName + "' on bean with name '" + beanName + "'");
                }
    
                Method methodToInvoke = ClassUtils.getInterfaceMethodIfPossible(initMethod);
                if (System.getSecurityManager() != null) {
                    AccessController.doPrivileged(() -> {
                        ReflectionUtils.makeAccessible(methodToInvoke);
                        return null;
                    });
    
                    try {
                        AccessController.doPrivileged(() -> {
                            return methodToInvoke.invoke(bean);
                        }, this.getAccessControlContext());
                    } catch (PrivilegedActionException var10) {
                        InvocationTargetException ex = (InvocationTargetException)var10.getException();
                        throw ex.getTargetException();
                    }
                } else {
                    try {
                        ReflectionUtils.makeAccessible(methodToInvoke);
                        methodToInvoke.invoke(bean);
                    } catch (InvocationTargetException var9) {
                        throw var9.getTargetException();
                    }
                }
    
            }
        }
    
        public Object applyBeanPostProcessorsAfterInitialization(Object existingBean, String beanName) throws BeansException {
            Object result = existingBean;
    
            Object current;
            for(Iterator var4 = this.getBeanPostProcessors().iterator(); var4.hasNext(); result = current) {
                BeanPostProcessor processor = (BeanPostProcessor)var4.next();
                current = processor.postProcessAfterInitialization(result, beanName);
                if (current == null) {
                    return result;
                }
            }
    
            return result;
        }

## \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* ##

**示例**

**\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\***

**pojo 层**

**Person**

@Data
    public class Person {
    
        private String name;
        private Integer age;
    }

**People**

@Data
    public class People {
    
        private String name;
        private Integer age;
    }

**Student**

@Data
    public class Student implements InitializingBean, DisposableBean {
    
        private String name;
        private Integer age;
    
        @PostConstruct
        public void fun(){
            System.out.println("student postConstruct");
        }
    
        @Override
        public void afterPropertiesSet() throws Exception {
            System.out.println("student afterPropertiesSet："+ this);
        }
    
        public void customInit(){
            System.out.println("student 自定义初始化方法：customInit");
        }
    
        @PreDestroy
        public void destroy(){
            System.out.println("student preDestroy");
        }
    
        public void customDestroy(){
            System.out.println("student 自定义销毁方法：customDestroy");
        }
    }

**\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\***

**config 层**

**DataConfig**

@Configuration
    public class DataConfig {
    
        @Bean("person")
        public Person initPerson(){
            Person person=new Person();
            person.setName("初始化名称 瓜田李下");
            person.setAge(20);
    
            return person;
        }
    
        @Bean(name = "student",initMethod = "customInit",destroyMethod = "customDestroy")
        public Student initStudent(){
            Student student=new Student();
            student.setName("初始化名称 海贼王");
            student.setAge(20);
    
            return student;
        }
    
        @Bean("people")
        public People initPeople(){
            People people=new People();
            people.setName("初始化名称 火影忍者");
            people.setAge(20);
    
            return people;
        }
    }

**CustomInstantiationAwareBeanPostProcessor**

@Configuration
    public class CustomInstantiationAwareBeanPostProcessor implements InstantiationAwareBeanPostProcessor {
    
        @Override
        public Object postProcessBeforeInstantiation(Class<?> beanClass, String beanName) throws BeansException {
            if (beanClass.getSimpleName().equals("Person")){
                Person person=new Person();
                person.setName("修改后名称 瓜田李下");
                person.setAge(20);
                System.out.println(person);
    
                return person;
            }
    
            return InstantiationAwareBeanPostProcessor.super.postProcessBeforeInstantiation(beanClass, beanName);
        }
    
        @Override
        public boolean postProcessAfterInstantiation(Object bean, String beanName) throws BeansException {
            if (bean instanceof People){
                return true;
            }
    
            return InstantiationAwareBeanPostProcessor.super.postProcessAfterInstantiation(bean, beanName);
        }
    
        @Override
        public PropertyValues postProcessProperties(PropertyValues pvs, Object bean, String beanName) throws BeansException {
            if (bean instanceof People){
                System.out.println(beanName+"  "+bean+"  "+pvs.getPropertyValues().length);
                MutablePropertyValues mutablePropertyValues=(MutablePropertyValues)pvs;
                mutablePropertyValues.addPropertyValue("name","修改后名称 火影忍者");
    
                return mutablePropertyValues;
            }
    
            return InstantiationAwareBeanPostProcessor.super.postProcessProperties(pvs, bean, beanName);
        }
    }

**\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\***

**controller 层**

**HelloController**

@RestController
    public class HelloController {
    
        @Resource
        private Person person;
    
        @Resource
        private People people;
    
        @Resource
        private Student student;
    
        @RequestMapping("/hello")
        public String hello(){
            System.out.println(person);
            System.out.println(people);
            System.out.println(student);
    
            return "success";
        }
    }

## \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* ##

**测试输出**

**启动后，控制台输出**

2021-08-07 19:49:48.008  INFO 15652 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
    2021-08-07 19:49:48.008  INFO 15652 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1443 ms
    Person(name=修改后名称 瓜田李下, age=20)
    people  People(name=初始化名称 火影忍者, age=20)  0
    
    # 执行顺序：@PostConstruct、afterpropertiesSet、自定义初始化方法（initMethod）
    student postConstruct
    student afterPropertiesSet：Student(name=初始化名称 海贼王, age=20)
    student 自定义初始化方法：customInit
    
    2021-08-07 19:49:48.625  INFO 15652 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
    2021-08-07 19:49:48.635  INFO 15652 --- [           main] tiationAwareBeanPostProcessorApplication : Started SpringbootInstantiationAwareBeanPostProcessorApplication in 2.505 seconds (JVM running for 3.54)

**localhost:8080/hello，控制台输出：**

Person(name=修改后名称 瓜田李下, age=20)
    People(name=修改后名称 火影忍者, age=20)
    Student(name=初始化名称 海贼王, age=20)
    
    # person属性在postProcessBeforeInstantiation中修改
    # people属性在postProcessAfterInstantiation、postProcessProperties中修改