一 入口
- beanFactory接口getBean初始化并返回对应bean
public Object getBean(String name) throws BeansException {
return doGetBean(name, null, null, false);
}
-
1 从单例bean三级缓存中依次尝试获取单例bean
-
2 缓存获取成功，普通bean或想获取factorybean(name前缀有&)则直接返回。 否则调用getObject()获取factoryBean对应的实际bean。
-
3 原型模式不支持循环依赖，若创建中则抛异常
-
4 当前factory中没找到则尝试到父factory中获取bean
-
5 若配置了依赖bean，则先创建依赖bean
-
6 单例bean，则获取bean，并同步骤2获取实际bean
-
7 原型bean，获取bean之前标记，获取bean之后删除标记。用于步骤3中控制避免循环依赖。获取bean之后处理同步骤2
-
8 范围bean，处理同原型bean。
-
9 指定类型，则进行类型转换
protected <T> T doGetBean(
final String name, final Class<T> requiredType, final Object[] args, boolean typeCheckOnly)
throws BeansException {
final String beanName = transformedBeanName(name);
Object bean;
Object sharedInstance = getSingleton(beanName);//1
if (sharedInstance != null && args == null) {//2
if (logger.isDebugEnabled()) {
if (isSingletonCurrentlyInCreation(beanName)) {
logger.debug("Returning eagerly cached instance of singleton bean '" + beanName +
"' that is not fully initialized yet - a consequence of a circular reference");
}
else {
logger.debug("Returning cached instance of singleton bean '" + beanName + "'");
}
}
bean = getObjectForBeanInstance(sharedInstance, name, beanName, null);
}
else {
if (isPrototypeCurrentlyInCreation(beanName)) {//3
throw new BeanCurrentlyInCreationException(beanName);
}
BeanFactory parentBeanFactory = getParentBeanFactory();
if (parentBeanFactory != null && !containsBeanDefinition(beanName)) {//4
String nameToLookup = originalBeanName(name);
if (args != null) {
return (T) parentBeanFactory.getBean(nameToLookup, args);
}
else {
return parentBeanFactory.getBean(nameToLookup, requiredType);
}
}
if (!typeCheckOnly) {
markBeanAsCreated(beanName);
}
try {
final RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);
checkMergedBeanDefinition(mbd, beanName, args);
String[] dependsOn = mbd.getDependsOn();//5
if (dependsOn != null) {
for (String dependsOnBean : dependsOn) {
if (isDependent(beanName, dependsOnBean)) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"Circular depends-on relationship between '" + beanName + "' and '" + dependsOnBean + "'");
}
registerDependentBean(dependsOnBean, beanName);
getBean(dependsOnBean);
}
}
if (mbd.isSingleton()) {//6
sharedInstance = getSingleton(beanName, new ObjectFactory<Object>() {
@Override
public Object getObject() throws BeansException {
try {
return createBean(beanName, mbd, args);
}
catch (BeansException ex) {
destroySingleton(beanName);
throw ex;
}
}
});
bean = getObjectForBeanInstance(sharedInstance, name, beanName, mbd);
}
else if (mbd.isPrototype()) {//7
Object prototypeInstance = null;
try {
beforePrototypeCreation(beanName);
prototypeInstance = createBean(beanName, mbd, args);
}
finally {
afterPrototypeCreation(beanName);
}
bean = getObjectForBeanInstance(prototypeInstance, name, beanName, mbd);
}
else {//8
String scopeName = mbd.getScope();
final Scope scope = this.scopes.get(scopeName);
if (scope == null) {
throw new IllegalStateException("No Scope registered for scope name '" + scopeName + "'");
}
try {
Object scopedInstance = scope.get(beanName, new ObjectFactory<Object>() {
@Override
public Object getObject() throws BeansException {
beforePrototypeCreation(beanName);
try {
return createBean(beanName, mbd, args);
}
finally {
afterPrototypeCreation(beanName);
}
}
});
bean = getObjectForBeanInstance(scopedInstance, name, beanName, mbd);
}
catch (IllegalStateException ex) {
throw new BeanCreationException(beanName,
"Scope '" + scopeName + "' is not active for the current thread; consider " +
"defining a scoped proxy for this bean if you intend to refer to it from a singleton",
ex);
}
}
}
catch (BeansException ex) {
cleanupAfterBeanCreationFailure(beanName);
throw ex;
}
}
if (requiredType != null && bean != null && !requiredType.isAssignableFrom(bean.getClass())) {//9
try {
return getTypeConverter().convertIfNecessary(bean, requiredType);
}
catch (TypeMismatchException ex) {
if (logger.isDebugEnabled()) {
logger.debug("Failed to convert bean '" + name + "' to required type [" +
ClassUtils.getQualifiedName(requiredType) + "]", ex);
}
throw new BeanNotOfRequiredTypeException(name, requiredType, bean.getClass());
}
}
return (T) bean;
}
二 创建bean
2.1 createBean
- 1 调用
InstantiationAwareBeanPostProcessor.postProcessBeforeInstantiation()实例化前置接口预处理bean，若有返回值则表示获取到bean对象，并调用BeanPostProcessor.postProcessAfterInitialization()初始化后置接口处理。 - 2 创建bean
protected Object createBean(final String beanName, final RootBeanDefinition mbd, final Object[] args)
throws BeanCreationException {
...
try {
Object bean = resolveBeforeInstantiation(beanName, mbd);//1
if (bean != null) {
return bean;
}
}
catch (Throwable ex) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"BeanPostProcessor before instantiation of bean failed", ex);
}
Object beanInstance = doCreateBean(beanName, mbd, args);//2
if (logger.isDebugEnabled()) {
logger.debug("Finished creating instance of bean '" + beanName + "'");
}
return beanInstance;
}
2.2 doCreateBean
- 1 factorybean创建bean或根据beanDefinition创建bean
- 2 实例化完成的单例bean放入工厂缓存中，用于支持循环依赖。属性依赖注入时，可从工厂缓存中获取到已实例化的单例bean
- 3 bean属性注入
- 4 bean初始化函数调用
- 5 支持循环依赖的单例bean获取实际bean
- 6 注册bean到容器回收资源bean列表中
disposableBeans
protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, final Object[] args) {
BeanWrapper instanceWrapper = null;
if (mbd.isSingleton()) {
instanceWrapper = this.factoryBeanInstanceCache.remove(beanName);
}
if (instanceWrapper == null) {
instanceWrapper = createBeanInstance(beanName, mbd, args);//1
}
final Object bean = (instanceWrapper != null ? instanceWrapper.getWrappedInstance() : null);
Class<?> beanType = (instanceWrapper != null ? instanceWrapper.getWrappedClass() : null);
// Allow post-processors to modify the merged bean definition.
synchronized (mbd.postProcessingLock) {
if (!mbd.postProcessed) {
applyMergedBeanDefinitionPostProcessors(mbd, beanType, beanName);
mbd.postProcessed = true;
}
}
boolean earlySingletonExposure = (mbd.isSingleton() && this.allowCircularReferences &&
isSingletonCurrentlyInCreation(beanName));
if (earlySingletonExposure) {//2
if (logger.isDebugEnabled()) {
logger.debug("Eagerly caching bean '" + beanName +
"' to allow for resolving potential circular references");
}
addSingletonFactory(beanName, new ObjectFactory<Object>() {
@Override
public Object getObject() throws BeansException {
return getEarlyBeanReference(beanName, mbd, bean);
}
});
}
Object exposedObject = bean;
try {
populateBean(beanName, mbd, instanceWrapper);//3
if (exposedObject != null) {
exposedObject = initializeBean(beanName, exposedObject, mbd);//4
}
}
catch (Throwable ex) {
if (ex instanceof BeanCreationException && beanName.equals(((BeanCreationException) ex).getBeanName())) {
throw (BeanCreationException) ex;
}
else {
throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Initialization of bean failed", ex);
}
}
if (earlySingletonExposure) {//5
Object earlySingletonReference = getSingleton(beanName, false);
if (earlySingletonReference != null) {
if (exposedObject == bean) {
exposedObject = earlySingletonReference;
}
else if (!this.allowRawInjectionDespiteWrapping && hasDependentBean(beanName)) {
String[] dependentBeans = getDependentBeans(beanName);
Set<String> actualDependentBeans = new LinkedHashSet<String>(dependentBeans.length);
for (String dependentBean : dependentBeans) {
if (!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 " +
"'getBeanNamesOfType' with the 'allowEagerInit' flag turned off, for example.");
}
}
}
}
try {//6
registerDisposableBeanIfNecessary(beanName, bean, mbd);
}
catch (BeanDefinitionValidationException ex) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Invalid destruction signature", ex);
}
return exposedObject;
}
三 属性注入
3.1 populateBean
- 1 beanDefinition中获取bean属性注入的值信息
- 2
InstantiationAwareBeanPostProcessors.postProcessAfterInstantiationbean实例化后置接口实现bean调用 - 3 按名称或者按类型的bean自动装配，即获取属性对应的注入值
- 4
InstantiationAwareBeanPostProcessors.postProcessPropertyValues属性注入前置接口调用 - 5 依赖bean检查
- 6 属性注入
protected void populateBean(String beanName, RootBeanDefinition mbd, BeanWrapper bw) {
PropertyValues pvs = mbd.getPropertyValues();//1
if (bw == null) {
if (!pvs.isEmpty()) {
throw new BeanCreationException(
mbd.getResourceDescription(), beanName, "Cannot apply property values to null instance");
}
else {
return;
}
}
boolean continueWithPropertyPopulation = true;
if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {
for (BeanPostProcessor bp : getBeanPostProcessors()) {//2
if (bp instanceof InstantiationAwareBeanPostProcessor) {
InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
if (!ibp.postProcessAfterInstantiation(bw.getWrappedInstance(), beanName)) {
continueWithPropertyPopulation = false;
break;
}
}
}
}
if (!continueWithPropertyPopulation) {
return;
}
if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_NAME ||
mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_TYPE) {//3
MutablePropertyValues newPvs = new MutablePropertyValues(pvs);
// Add property values based on autowire by name if applicable.
if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_NAME) {
autowireByName(beanName, mbd, bw, newPvs);
}
// Add property values based on autowire by type if applicable.
if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_TYPE) {
autowireByType(beanName, mbd, bw, newPvs);
}
pvs = newPvs;
}
boolean hasInstAwareBpps = hasInstantiationAwareBeanPostProcessors();
boolean needsDepCheck = (mbd.getDependencyCheck() != RootBeanDefinition.DEPENDENCY_CHECK_NONE);
if (hasInstAwareBpps || needsDepCheck) {
PropertyDescriptor[] filteredPds = filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching);
if (hasInstAwareBpps) {//4
for (BeanPostProcessor bp : getBeanPostProcessors()) {
if (bp instanceof InstantiationAwareBeanPostProcessor) {
InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
pvs = ibp.postProcessPropertyValues(pvs, filteredPds, bw.getWrappedInstance(), beanName);
if (pvs == null) {
return;
}
}
}
}
if (needsDepCheck) {//5
checkDependencies(beanName, mbd, filteredPds, pvs);
}
}
applyPropertyValues(beanName, mbd, bw, pvs);//6
}
四 初始化函数
- 1 调用Aware类型接口
private void invokeAwareMethods(final String beanName, final Object bean) {
if (bean instanceof Aware) {
if (bean instanceof BeanNameAware) {
((BeanNameAware) bean).setBeanName(beanName);
}
if (bean instanceof BeanClassLoaderAware) {
((BeanClassLoaderAware) bean).setBeanClassLoader(getBeanClassLoader());
}
if (bean instanceof BeanFactoryAware) {
((BeanFactoryAware) bean).setBeanFactory(AbstractAutowireCapableBeanFactory.this);
}
}
}
- 2
BeanPostProcessor.postProcessBeforeInitialization初始化前置接口调用 - 3 初始化接口调用
InitializingBean.afterPropertiesSet()＋initMethodName - 4
BeanPostProcessor.postProcessAfterInitialization初始化后置接口调用
protected Object initializeBean(final String beanName, final Object bean, RootBeanDefinition mbd) {
if (System.getSecurityManager() != null) {
AccessController.doPrivileged(new PrivilegedAction<Object>() {
@Override
public Object run() {
invokeAwareMethods(beanName, bean);
return null;
}
}, getAccessControlContext());
}
else {
invokeAwareMethods(beanName, bean);//1
}
Object wrappedBean = bean;
if (mbd == null || !mbd.isSynthetic()) {
wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);//2
}
try {
invokeInitMethods(beanName, wrappedBean, mbd);//3
}
catch (Throwable ex) {
throw new BeanCreationException(
(mbd != null ? mbd.getResourceDescription() : null),
beanName, "Invocation of init method failed", ex);
}
if (mbd == null || !mbd.isSynthetic()) {
wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);//4
}
return wrappedBean;
}
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