接上篇Spring源码之IoC容器初始化过程，以FileSystemXmlApplicationContext容器为例
因为FileSystemXmlApplicationContext使用的容器为DefaultListableBeanFactory，所以该篇基于DefaultListableBeanFactory的实现分析依赖注入过程。
目录
获取Bean的总体流程
getBean流程：
依赖注入通过BeanFactory的getBean方法触发。
DefaultListableBeanFactory的getBean方法通过继承AbstractAutowireCapableBeanFactory，AbstractAutowireCapableBeanFactory继承AbstractBeanFactory获得，具体的实现在AbstractBeanFactory中。
1、通过getBean方法触发依赖注入
2、getBean方法调用doGetBean方法，这是实际触发依赖注入的方法
3、先从缓存中取得Bean，处理那些已经被创建过的单件模式的Bean，对这种Bean的请求不需要重复的创建
4、如果从缓存中获得Bean，通过getObjectForBeanInstance方法完成FactoryBean的相关处理，取得FactoryBean的处理结果。
5、如果从缓存中未获得Bean，并且双亲BeanFactory不为null。检查当前IoC容器中是否存在对应的BeanDefinition，也就是检查是否能在当前的BeanFactory的Map中取得需要的Bean。
6、如果在当前的BeanFactory工厂中取不到BeanDefinition，则到双亲BeanFactory中取，也就是调用双亲BeanFactory的getBean方法。如果在当前的双亲工厂中还取不到，则递归顺着双亲BeanFactory链一直向上查找。
7、如果双亲BeanFactory为null，或者当前IoC容器中存在对应的BeanDefinition，根据Bean的名称获取BeanDefinition。
8、获取当前Bean的所有依赖的Bean名称，把依赖的Bean注册到dependentBeanMap中。并调用getBean方法注册每个依赖Bean的依赖Bean。调用getBean方法传入依赖Bean名称，这样会触发getBean的递归调用，直到取到一个没有任何依赖的Bean为止。
9、判断Bean是Singleton还是Prototype，通过调用createBean方法创建Bean实例，通过getObjectForBeanInstance方法完成FactoryBean的相关处理。
10、最后对Bean进行类型检查，如果没问题，则返回这个新创建的Bean，这个Bean是包含了依赖关系的Bean。
Bean对象的实例化
createBean方法流程：
该方法在AbstractAutowireCapableBeanFactory中实现
1、判断需要创建的Bean是否可以实例化，这个类是否可以通过类装载器来载入
2、如果Bean配置了PostProcessor，则获取一个proxy代理对象。
3、createBean调用doCreateBean创建Bean。doCreateBean中，用一个BeanWrapper持有创建出来的Bean对象。
4、如果是Singleton，先把缓存中的同名Bean清除。如果缓存找那个存在对应的Bean，则返回对应的Bean并作为即将获取的Bean，如果缓存中不存在，则调用createBeanInstance创建Bean对象。
5、调用populateBean方法对Bean进行初始化，以及依赖关系的注入。
createBeanInstance方法：
1、确认需要创建的Bean实例的类可以实例化。
2、如果instanceSupplier不为空，则通过instanceSupplier直接获取实例。
3、如果有工厂方法，则通过工厂方法对Bean进行实例化。
4、以上两种情况都不满足，则使用构造函数进行实例化。
5、通过构造函数后置处理器determineConstructorsFromBeanPostProcessors, 来选择使用哪个构造函数来实例化Bean。
6、如果构造函数后置处理器返回的构造函数为空，则用默认的构造函数对Bean进行实例化。通过instantiateBean(beanName, mbd)方法进行实例化。
instantiateBean方法：
1、使用默认的实例化策略对Bean进行实例化，默认的策略是使用CGLIB来对Bean进行实例化。
2、调用instantiate实例化Bean
SimpleInstantiationStrategy中的instantiate方法：
MethodOverrides的作用是在spring配置中存在lookup-mehtod和rreplace-method的，而这两个配置在加载xml的时候就会统一存放在BeanDefinition中的methodOverrides属性里
1、判断MethodOverrides是否为空，不为空时，使用CGLIB来实例化对象。
2、MethodOverrides为空时，取得指定的构造器或者生成对象的工厂方法来对Bean进行实例化，通过BeanUtils进行实例化，BeanUtils通过Constructor来实例化Bean，使用的是JVM的反射功能。
Bean对象依赖关系的注入
populateBean方法:
1、在创建Bean后，执行Bean的后置处理BeanPostProcessor
2、获取Bean的所有属性PropertyValues
3、开始进行依赖注入，先处理autowire的注入
4、根据Bean的名字或者类型，调用autowireByName或autowireByType方法，来完成Bean的autowire注入
5、调用applyPropertyValues对属性进行注入
6、applyPropertyValues中，通过BeanDefinitionValueResolver对BeanDefinition进行解析，applyPropertyValues方法调用了resolveValueIfNecessary方法，resolveValueIfNecessary方法调用了resolveReference方法，resolveValueIfNecessary包含了所有对注入类型的处理。
7、通过bw.setPropertyValues(new MutablePropertyValues(deepCopy));进行依赖注入
resolveReference方法：
1、根据RuntimeBeanReference判断每个PropertyValue，也就是依赖对象，是否在双亲IoC容器中
2、如果是在双亲IoC容器中，Bean的类型不为空，根据类型从双亲IoC容器中获取Bean，否则根据名字从双亲IoC容器中获取Bean
3、如果不在双亲IoC容器中，从当前容器获取Bean的实例和名字，调用当前容器的getBean获取
4、完成以上步骤后，已经为依赖注入准备好了条件，接下来就是真正注入的方法，在BeanWrapper的setPropertyValues中实现的，具体是在BeanWrapperImpl中实现的。
5、通过bw.setPropertyValues方法，遍历所有的PropertyValue，挨个进行设置
6、最终在BeanWrapperImpl中的setValue方法中，通过反射进行注入
总结：
在Bean的创建爱你和对象依赖注入的过程中，需要依据BeanDefinition中的信息来递归地完成依赖注入。从上面的几个递归过程中可以看到，这些递归都是以getBean为入口的。
一个递归是在上下文体系中查找需要的Bean和创建Bean的递归调用；另一个递归是在依赖注入时，通过递归调用容器的getBean方法，得到当前Bean的依赖Bean，同时也触发对依赖Bean的创建和注入。
在对Bean的属性进行依赖注入时，解析的过程也是一个递归的过程。这样，根据依赖关系，一层一层地完成Bean的创建和注入，直到最后完成当前Bean的创建。有了这个顶层Bean的创建和对它的属性依赖注入的完成，意味着和当前Bean相关的整个依赖链的注入也完成了。
源码
BeanFactory中定义了getBean方法，依赖注入正是通过getBean方法触发
public interface BeanFactory {
String FACTORY_BEAN_PREFIX = "&";
Object getBean(String var1) throws BeansException;
<T> T getBean(String var1, Class<T> var2) throws BeansException;
Object getBean(String var1, Object... var2) throws BeansException;
<T> T getBean(Class<T> var1) throws BeansException;
<T> T getBean(Class<T> var1, Object... var2) throws BeansException;
<T> ObjectProvider<T> getBeanProvider(Class<T> var1);
<T> ObjectProvider<T> getBeanProvider(ResolvableType var1);
boolean containsBean(String var1);
boolean isSingleton(String var1) throws NoSuchBeanDefinitionException;
boolean isPrototype(String var1) throws NoSuchBeanDefinitionException;
boolean isTypeMatch(String var1, ResolvableType var2) throws NoSuchBeanDefinitionException;
boolean isTypeMatch(String var1, Class<?> var2) throws NoSuchBeanDefinitionException;
@Nullable
Class<?> getType(String var1) throws NoSuchBeanDefinitionException;
@Nullable
Class<?> getType(String var1, boolean var2) throws NoSuchBeanDefinitionException;
String[] getAliases(String var1);
}
doGetBean方法源码
protected <T> T doGetBean(String name, @Nullable Class<T> requiredType, @Nullable Object[] args, boolean typeCheckOnly) throws BeansException {
String beanName = this.transformedBeanName(name);
// 先从缓存中取得Bean，处理那些已经被创建过的单件模式的Bean，对这种Bean的请求不需要重复的创建
Object sharedInstance = this.getSingleton(beanName);
Object bean;
if (sharedInstance != null && args == null) {
if (this.logger.isTraceEnabled()) {
if (this.isSingletonCurrentlyInCreation(beanName)) {
this.logger.trace("Returning eagerly cached instance of singleton bean '" + beanName + "' that is not fully initialized yet - a consequence of a circular reference");
} else {
this.logger.trace("Returning cached instance of singleton bean '" + beanName + "'");
}
}
// 如果从缓存中获得Bean，通过getObjectForBeanInstance方法完成FactoryBean的相关处理，
// 取得FactoryBean的处理结果。
bean = this.getObjectForBeanInstance(sharedInstance, name, beanName, (RootBeanDefinition)null);
} else {
if (this.isPrototypeCurrentlyInCreation(beanName)) {
throw new BeanCurrentlyInCreationException(beanName);
}
// 如果从缓存中未获得Bean，并且双亲BeanFactory不为null。
// 检查当前IoC容器中是否存在对应的BeanDefinition，也就是检查是否能在当前的BeanFactory的Map中取得需要的Bean。
BeanFactory parentBeanFactory = this.getParentBeanFactory();
if (parentBeanFactory != null && !this.containsBeanDefinition(beanName)) {
// 如果在当前的BeanFactory工厂中取不到BeanDefinition，则到双亲BeanFactory中取，
// 也就是调用双亲BeanFactory的getBean方法。如果在当前的双亲工厂中还取不到，
// 则递归顺着双亲BeanFactory链一直向上查找。
String nameToLookup = this.originalBeanName(name);
if (parentBeanFactory instanceof AbstractBeanFactory) {
return ((AbstractBeanFactory)parentBeanFactory).doGetBean(nameToLookup, requiredType, args, typeCheckOnly);
}
if (args != null) {
return parentBeanFactory.getBean(nameToLookup, args);
}
if (requiredType != null) {
return parentBeanFactory.getBean(nameToLookup, requiredType);
}
return parentBeanFactory.getBean(nameToLookup);
}
if (!typeCheckOnly) {
this.markBeanAsCreated(beanName);
}
// 如果双亲BeanFactory为null，或者当前IoC容器中存在对应的BeanDefinition，
// 根据Bean的名称获取BeanDefinition。
try {
RootBeanDefinition mbd = this.getMergedLocalBeanDefinition(beanName);
this.checkMergedBeanDefinition(mbd, beanName, args);
String[] dependsOn = mbd.getDependsOn();
String[] var11;
if (dependsOn != null) {
var11 = dependsOn;
int var12 = dependsOn.length;
// 获取当前Bean的所有依赖的Bean名称，把依赖的Bean注册到dependentBeanMap中。
// 并调用getBean方法注册每个依赖Bean的依赖Bean。
for(int var13 = 0; var13 < var12; ++var13) {
String dep = var11[var13];
if (this.isDependent(beanName, dep)) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Circular depends-on relationship between '" + beanName + "' and '" + dep + "'");
}
this.registerDependentBean(dep, beanName);
try {
this.getBean(dep);
} catch (NoSuchBeanDefinitionException var24) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName, "'" + beanName + "' depends on missing bean '" + dep + "'", var24);
}
}
}
// 判断Bean是Singleton还是Prototype，通过调用createBean方法创建Bean实例，
// 通过getObjectForBeanInstance方法完成FactoryBean的相关处理。
if (mbd.isSingleton()) {
sharedInstance = this.getSingleton(beanName, () -> {
try {
return this.createBean(beanName, mbd, args);
} catch (BeansException var5) {
this.destroySingleton(beanName);
throw var5;
}
});
bean = this.getObjectForBeanInstance(sharedInstance, name, beanName, mbd);
} else if (mbd.isPrototype()) {
var11 = null;
Object prototypeInstance;
try {
this.beforePrototypeCreation(beanName);
prototypeInstance = this.createBean(beanName, mbd, args);
} finally {
this.afterPrototypeCreation(beanName);
}
bean = this.getObjectForBeanInstance(prototypeInstance, name, beanName, mbd);
} else {
String scopeName = mbd.getScope();
if (!StringUtils.hasLength(scopeName)) {
throw new IllegalStateException("No scope name defined for bean ��" + beanName + "'");
}
Scope 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, () -> {
this.beforePrototypeCreation(beanName);
Object var4;
try {
var4 = this.createBean(beanName, mbd, args);
} finally {
this.afterPrototypeCreation(beanName);
}
return var4;
});
bean = this.getObjectForBeanInstance(scopedInstance, name, beanName, mbd);
} catch (IllegalStateException var23) {
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", var23);
}
}
} catch (BeansException var26) {
this.cleanupAfterBeanCreationFailure(beanName);
throw var26;
}
}
// 最后对Bean进行类型检查，如果没问题，
// 则返回这个新创建的Bean，这个Bean是包含了依赖关系的Bean。
if (requiredType != null && !requiredType.isInstance(bean)) {
try {
T convertedBean = this.getTypeConverter().convertIfNecessary(bean, requiredType);
if (convertedBean == null) {
throw new BeanNotOfRequiredTypeException(name, requiredType, bean.getClass());
} else {
return convertedBean;
}
} catch (TypeMismatchException var25) {
if (this.logger.isTraceEnabled()) {
this.logger.trace("Failed to convert bean '" + name + "' to required type '" + ClassUtils.getQualifiedName(requiredType) + "'", var25);
}
throw new BeanNotOfRequiredTypeException(name, requiredType, bean.getClass());
}
} else {
return bean;
}
}
createBean方法
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);
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);
}
}
doCreateBean方法
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);
}
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);
exposedObject = this.initializeBean(beanName, exposedObject, mbd);
} 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);
}
}
createBeanInstance方法创建对象
protected BeanWrapper createBeanInstance(String beanName, RootBeanDefinition mbd, @Nullable Object[] args) {
Class<?> beanClass = this.resolveBeanClass(mbd, beanName, new Class[0]);
if (beanClass != null && !Modifier.isPublic(beanClass.getModifiers()) && !mbd.isNonPublicAccessAllowed()) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Bean class isn't public, and non-public access not allowed: " + beanClass.getName());
} else {
Supplier<?> instanceSupplier = mbd.getInstanceSupplier();
if (instanceSupplier != null) {
return this.obtainFromSupplier(instanceSupplier, beanName);
} else if (mbd.getFactoryMethodName() != null) {
return this.instantiateUsingFactoryMethod(beanName, mbd, args);
} else {
boolean resolved = false;
boolean autowireNecessary = false;
if (args == null) {
synchronized(mbd.constructorArgumentLock) {
if (mbd.resolvedConstructorOrFactoryMethod != null) {
resolved = true;
autowireNecessary = mbd.constructorArgumentsResolved;
}
}
}
if (resolved) {
return autowireNecessary ? this.autowireConstructor(beanName, mbd, (Constructor[])null, (Object[])null) : this.instantiateBean(beanName, mbd);
} else {
Constructor<?>[] ctors = this.determineConstructorsFromBeanPostProcessors(beanClass, beanName);
if (ctors == null && mbd.getResolvedAutowireMode() != 3 && !mbd.hasConstructorArgumentValues() && ObjectUtils.isEmpty(args)) {
ctors = mbd.getPreferredConstructors();
return ctors != null ? this.autowireConstructor(beanName, mbd, ctors, (Object[])null) : this.instantiateBean(beanName, mbd);
} else {
return this.autowireConstructor(beanName, mbd, ctors, args);
}
}
}
}
}
instantiateBean方法
protected BeanWrapper instantiateBean(String beanName, RootBeanDefinition mbd) {
try {
Object beanInstance;
if (System.getSecurityManager() != null) {
beanInstance = AccessController.doPrivileged(() -> {
return this.getInstantiationStrategy().instantiate(mbd, beanName, this);
}, this.getAccessControlContext());
} else {
beanInstance = this.getInstantiationStrategy().instantiate(mbd, beanName, this);
}
BeanWrapper bw = new BeanWrapperImpl(beanInstance);
this.initBeanWrapper(bw);
return bw;
} catch (Throwable var5) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Instantiation of bean failed", var5);
}
}
通过反射创建对象
BeanUtils.instantiateClass(constructorToUse, new Object[0])
public static <T> T instantiateClass(Constructor<T> ctor, Object... args) throws BeanInstantiationException {
Assert.notNull(ctor, "Constructor must not be null");
try {
ReflectionUtils.makeAccessible(ctor);
if (KotlinDetector.isKotlinReflectPresent() && KotlinDetector.isKotlinType(ctor.getDeclaringClass())) {
return BeanUtils.KotlinDelegate.instantiateClass(ctor, args);
} else {
Class<?>[] parameterTypes = ctor.getParameterTypes();
Assert.isTrue(args.length <= parameterTypes.length, "Can't specify more arguments than constructor parameters");
Object[] argsWithDefaultValues = new Object[args.length];
for(int i = 0; i < args.length; ++i) {
if (args[i] == null) {
Class<?> parameterType = parameterTypes[i];
argsWithDefaultValues[i] = parameterType.isPrimitive() ? DEFAULT_TYPE_VALUES.get(parameterType) : null;
} else {
argsWithDefaultValues[i] = args[i];
}
}
return ctor.newInstance(argsWithDefaultValues);
}
} catch (InstantiationException var6) {
throw new BeanInstantiationException(ctor, "Is it an abstract class?", var6);
} catch (IllegalAccessException var7) {
throw new BeanInstantiationException(ctor, "Is the constructor accessible?", var7);
} catch (IllegalArgumentException var8) {
throw new BeanInstantiationException(ctor, "Illegal arguments for constructor", var8);
} catch (InvocationTargetException var9) {
throw new BeanInstantiationException(ctor, "Constructor threw exception", var9.getTargetException());
}
}
通过CGLIB创建对象
this.instantiateWithMethodInjection(bd, beanName, owner)
protected Object instantiateWithMethodInjection(RootBeanDefinition bd, @Nullable String beanName, BeanFactory owner) {
return this.instantiateWithMethodInjection(bd, beanName, owner, (Constructor)null);
}
protected Object instantiateWithMethodInjection(RootBeanDefinition bd, @Nullable String beanName, BeanFactory owner, @Nullable Constructor<?> ctor, Object... args) {
return (new CglibSubclassingInstantiationStrategy.CglibSubclassCreator(bd, owner)).instantiate(ctor, args);
}
public Object instantiate(@Nullable Constructor<?> ctor, Object... args) {
Class<?> subclass = this.createEnhancedSubclass(this.beanDefinition);
Object instance;
if (ctor == null) {
instance = BeanUtils.instantiateClass(subclass);
} else {
try {
Constructor<?> enhancedSubclassConstructor = subclass.getConstructor(ctor.getParameterTypes());
instance = enhancedSubclassConstructor.newInstance(args);
} catch (Exception var6) {
throw new BeanInstantiationException(this.beanDefinition.getBeanClass(), "Failed to invoke constructor for CGLIB enhanced subclass [" + subclass.getName() + "]", var6);
}
}
Factory factory = (Factory)instance;
factory.setCallbacks(new Callback[]{
NoOp.INSTANCE, new CglibSubclassingInstantiationStrategy.LookupOverrideMethodInterceptor(this.beanDefinition, this.owner), new CglibSubclassingInstantiationStrategy.ReplaceOverrideMethodInterceptor(this.beanDefinition, this.owner)});
return instance;
}
createEnhancedSubclass方法
private Class<?> createEnhancedSubclass(RootBeanDefinition beanDefinition) {
Enhancer enhancer = new Enhancer();
enhancer.setSuperclass(beanDefinition.getBeanClass());
enhancer.setNamingPolicy(SpringNamingPolicy.INSTANCE);
if (this.owner instanceof ConfigurableBeanFactory) {
ClassLoader cl = ((ConfigurableBeanFactory)this.owner).getBeanClassLoader();
enhancer.setStrategy(new ClassLoaderAwareGeneratorStrategy(cl));
}
enhancer.setCallbackFilter(new CglibSubclassingInstantiationStrategy.MethodOverrideCallbackFilter(beanDefinition));
enhancer.setCallbackTypes(CALLBACK_TYPES);
return enhancer.createClass();
}
populateBean方法设置依赖关系
populateBean方法
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.getBeanPostProcessors().iterator();
while(var4.hasNext()) {
BeanPostProcessor bp = (BeanPostProcessor)var4.next();
if (bp instanceof InstantiationAwareBeanPostProcessor) {
InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor)bp;
if (!ibp.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();
}
Iterator var9 = this.getBeanPostProcessors().iterator();
while(var9.hasNext()) {
BeanPostProcessor bp = (BeanPostProcessor)var9.next();
if (bp instanceof InstantiationAwareBeanPostProcessor) {
InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor)bp;
PropertyValues pvsToUse = ibp.postProcessProperties((PropertyValues)pvs, bw.getWrappedInstance(), beanName);
if (pvsToUse == null) {
if (filteredPds == null) {
filteredPds = this.filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching);
}
pvsToUse = ibp.postProcessPropertyValues((PropertyValues)pvs, filteredPds, bw.getWrappedInstance(), beanName);
if (pvsToUse == null) {
return;
}
}
pvs = pvsToUse;
}
}
}
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);
}
}
}
applyPropertyValues方法
protected void applyPropertyValues(String beanName, BeanDefinition mbd, BeanWrapper bw, PropertyValues pvs) {
if (!pvs.isEmpty()) {
if (System.getSecurityManager() != null && bw instanceof BeanWrapperImpl) {
((BeanWrapperImpl)bw).setSecurityContext(this.getAccessControlContext());
}
MutablePropertyValues mpvs = null;
List original;
if (pvs instanceof MutablePropertyValues) {
mpvs = (MutablePropertyValues)pvs;
if (mpvs.isConverted()) {
try {
bw.setPropertyValues(mpvs);
return;
} catch (BeansException var18) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Error setting property values", var18);
}
}
original = mpvs.getPropertyValueList();
} else {
original = Arrays.asList(pvs.getPropertyValues());
}
TypeConverter converter = this.getCustomTypeConverter();
if (converter == null) {
converter = bw;
}
BeanDefinitionValueResolver valueResolver = new BeanDefinitionValueResolver(this, beanName, mbd, (TypeConverter)converter);
List<PropertyValue> deepCopy = new ArrayList(original.size());
boolean resolveNecessary = false;
Iterator var11 = original.iterator();
while(true) {
while(var11.hasNext()) {
PropertyValue pv = (PropertyValue)var11.next();
if (pv.isConverted()) {
deepCopy.add(pv);
} else {
String propertyName = pv.getName();
Object originalValue = pv.getValue();
if (originalValue == AutowiredPropertyMarker.INSTANCE) {
Method writeMethod = bw.getPropertyDescriptor(propertyName).getWriteMethod();
if (writeMethod == null) {
throw new IllegalArgumentException("Autowire marker for property without write method: " + pv);
}
originalValue = new DependencyDescriptor(new MethodParameter(writeMethod, 0), true);
}
Object resolvedValue = valueResolver.resolveValueIfNecessary(pv, originalValue);
Object convertedValue = resolvedValue;
boolean convertible = bw.isWritableProperty(propertyName) && !PropertyAccessorUtils.isNestedOrIndexedProperty(propertyName);
if (convertible) {
convertedValue = this.convertForProperty(resolvedValue, propertyName, bw, (TypeConverter)converter);
}
if (resolvedValue == originalValue) {
if (convertible) {
pv.setConvertedValue(convertedValue);
}
deepCopy.add(pv);
} else if (convertible && originalValue instanceof TypedStringValue && !((TypedStringValue)originalValue).isDynamic() && !(convertedValue instanceof Collection) && !ObjectUtils.isArray(convertedValue)) {
pv.setConvertedValue(convertedValue);
deepCopy.add(pv);
} else {
resolveNecessary = true;
deepCopy.add(new PropertyValue(pv, convertedValue));
}
}
}
if (mpvs != null && !resolveNecessary) {
mpvs.setConverted();
}
try {
bw.setPropertyValues(new MutablePropertyValues(deepCopy));
return;
} catch (BeansException var19) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Error setting property values", var19);
}
}
}
}
resolveValueIfNecessary方法
public Object resolveValueIfNecessary(Object argName, @Nullable Object value) {
if (value instanceof RuntimeBeanReference) {
RuntimeBeanReference ref = (RuntimeBeanReference)value;
return this.resolveReference(argName, ref);
} else if (value instanceof RuntimeBeanNameReference) {
String refName = ((RuntimeBeanNameReference)value).getBeanName();
refName = String.valueOf(this.doEvaluate(refName));
if (!this.beanFactory.containsBean(refName)) {
throw new BeanDefinitionStoreException("Invalid bean name '" + refName + "' in bean reference for " + argName);
} else {
return refName;
}
} else if (value instanceof BeanDefinitionHolder) {
BeanDefinitionHolder bdHolder = (BeanDefinitionHolder)value;
return this.resolveInnerBean(argName, bdHolder.getBeanName(), bdHolder.getBeanDefinition());
} else if (value instanceof BeanDefinition) {
BeanDefinition bd = (BeanDefinition)value;
String innerBeanName = "(inner bean)#" + ObjectUtils.getIdentityHexString(bd);
return this.resolveInnerBean(argName, innerBeanName, bd);
} else {
Object valueObject;
if (value instanceof DependencyDescriptor) {
Set<String> autowiredBeanNames = new LinkedHashSet(4);
valueObject = this.beanFactory.resolveDependency((DependencyDescriptor)value, this.beanName, autowiredBeanNames, this.typeConverter);
Iterator var19 = autowiredBeanNames.iterator();
while(var19.hasNext()) {
String autowiredBeanName = (String)var19.next();
if (this.beanFactory.containsBean(autowiredBeanName)) {
this.beanFactory.registerDependentBean(autowiredBeanName, this.beanName);
}
}
return valueObject;
} else if (value instanceof ManagedArray) {
ManagedArray array = (ManagedArray)value;
Class<?> elementType = array.resolvedElementType;
if (elementType == null) {
String elementTypeName = array.getElementTypeName();
if (StringUtils.hasText(elementTypeName)) {
try {
elementType = ClassUtils.forName(elementTypeName, this.beanFactory.getBeanClassLoader());
array.resolvedElementType = elementType;
} catch (Throwable var7) {
throw new BeanCreationException(this.beanDefinition.getResourceDescription(), this.beanName, "Error resolving array type for " + argName, var7);
}
} else {
elementType = Object.class;
}
}
return this.resolveManagedArray(argName, (List)value, elementType);
} else if (value instanceof ManagedList) {
return this.resolveManagedList(argName, (List)value);
} else if (value instanceof ManagedSet) {
return this.resolveManagedSet(argName, (Set)value);
} else if (value instanceof ManagedMap) {
return this.resolveManagedMap(argName, (Map)value);
} else if (value instanceof ManagedProperties) {
Properties original = (Properties)value;
Properties copy = new Properties();
original.forEach((propKey, propValue) -> {
if (propKey instanceof TypedStringValue) {
propKey = this.evaluate((TypedStringValue)propKey);
}
if (propValue instanceof TypedStringValue) {
propValue = this.evaluate((TypedStringValue)propValue);
}
if (propKey != null && propValue != null) {
copy.put(propKey, propValue);
} else {
throw new BeanCreationException(this.beanDefinition.getResourceDescription(), this.beanName, "Error converting Properties key/value pair for " + argName + ": resolved to null");
}
});
return copy;
} else if (value instanceof TypedStringValue) {
TypedStringValue typedStringValue = (TypedStringValue)value;
valueObject = this.evaluate(typedStringValue);
try {
Class<?> resolvedTargetType = this.resolveTargetType(typedStringValue);
return resolvedTargetType != null ? this.typeConverter.convertIfNecessary(valueObject, resolvedTargetType) : valueObject;
} catch (Throwable var8) {
throw new BeanCreationException(this.beanDefinition.getResourceDescription(), this.beanName, "Error converting typed String value for " + argName, var8);
}
} else {
return value instanceof NullBean ? null : this.evaluate(value);
}
}
}
resolveReference方法
applyPropertyValues方法调用了resolveValueIfNecessary方法，resolveValueIfNecessary方法调用了resolveReference方法
private Object resolveReference(Object argName, RuntimeBeanReference ref) {
try {
Class<?> beanType = ref.getBeanType();
Object bean;
if (ref.isToParent()) {
BeanFactory parent = this.beanFactory.getParentBeanFactory();
if (parent == null) {
throw new BeanCreationException(this.beanDefinition.getResourceDescription(), this.beanName, "Cannot resolve reference to bean " + ref + " in parent factory: no parent factory available");
}
if (beanType != null) {
bean = parent.getBean(beanType);
} else {
bean = parent.getBean(String.valueOf(this.doEvaluate(ref.getBeanName())));
}
} else {
String resolvedName;
if (beanType != null) {
NamedBeanHolder<?> namedBean = this.beanFactory.resolveNamedBean(beanType);
bean = namedBean.getBeanInstance();
resolvedName = namedBean.getBeanName();
} else {
resolvedName = String.valueOf(this.doEvaluate(ref.getBeanName()));
bean = this.beanFactory.getBean(resolvedName);
}
this.beanFactory.registerDependentBean(resolvedName, this.beanName);
}
if (bean instanceof NullBean) {
bean = null;
}
return bean;
} catch (BeansException var7) {
throw new BeanCreationException(this.beanDefinition.getResourceDescription(), this.beanName, "Cannot resolve reference to bean '" + ref.getBeanName() + "' while setting " + argName, var7);
}
}