spring源码解析bean初始化与依赖注入四

2019独角兽企业重金招聘Python工程师标准>>>

前言

本文转自“天河聊技术”微信公众号

本次继续介绍spring源码解析bean初始化、依赖注入的部分

正文

上次介绍到这个方法

org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#doCreateBean这一行

// 今早的缓存单例对象以便循环引用
if (earlySingletonExposure) {
Object earlySingletonReference &＃61; getSingleton(beanName, false);
if (earlySingletonReference !&＃61; null) {
if (exposedObject &＃61;&＃61; bean) {
exposedObject &＃61; earlySingletonReference;
}
// 初始化的bean没被包装又有依赖
else if (!this.allowRawInjectionDespiteWrapping && hasDependentBean(beanName)) {
// 获取依赖的bean
String[] dependentBeans &＃61; getDependentBeans(beanName);
Set actualDependentBeans &＃61; new LinkedHashSet<>(dependentBeans.length);
for (String dependentBean : dependentBeans) {
if (!removeSingletonIfCreatedForTypeCheckOnly(dependentBean)) {
actualDependentBeans.add(dependentBean);
}
}
if (!actualDependentBeans.isEmpty()) {
throw new BeanCurrentlyInCreationException(beanName,
"Bean with name &＃39;" &＃43; beanName &＃43; "&＃39; has been injected into other beans [" &＃43;
StringUtils.collectionToCommaDelimitedString(actualDependentBeans) &＃43;
"] in its raw version as part of a circular reference, but has eventually been " &＃43;
"wrapped. This means that said other beans do not use the final version of the " &＃43;
"bean. This is often the result of over-eager type matching - consider using " &＃43;
"&＃39;getBeanNamesOfType&＃39; with the &＃39;allowEagerInit&＃39; flag turned off, for example.");
}
}
}
}

这一行

// Register bean as disposable.注册的bean作为可销毁的
try {
registerDisposableBeanIfNecessary(beanName, bean, mbd);
}

进入org.springframework.beans.factory.support.AbstractBeanFactory#registerDisposableBeanIfNecessary注册可销毁的bean

*/
protected void registerDisposableBeanIfNecessary(String beanName, Object bean, RootBeanDefinition mbd) {
AccessControlContext acc &＃61; (System.getSecurityManager() !&＃61; null ? getAccessControlContext() : null);
// 不是原型模式&＃xff0c;可以销毁
if (!mbd.isPrototype() && requiresDestruction(bean, mbd)) {
// 如果是单例
if (mbd.isSingleton()) {
// Register a DisposableBean implementation that performs all destruction
// work for the given bean: DestructionAwareBeanPostProcessors,
// DisposableBean interface, custom destroy method.
// 注册销毁的bean&＃xff0c;这一部分在bean定义解析的部分介绍过&＃xff0c;这里不作介绍了
registerDisposableBean(beanName,
new DisposableBeanAdapter(bean, beanName, mbd, getBeanPostProcessors(), acc));
}
else {
// A bean with a custom scope...
Scope scope &＃61; this.scopes.get(mbd.getScope());
if (scope &＃61;&＃61; null) {
throw new IllegalStateException("No Scope registered for scope name &＃39;" &＃43; mbd.getScope() &＃43; "&＃39;");
}
// 销毁后的回调方法
scope.registerDestructionCallback(beanName,
new DisposableBeanAdapter(bean, beanName, mbd, getBeanPostProcessors(), acc));
}
}
}

返回org.springframework.beans.factory.support.AbstractBeanFactory#doGetBean这一行

try {
// bean初始化
return createBean(beanName, mbd, args);
}

这里介绍完了&＃xff0c;往下

// 发生异常销毁单例的bean
destroySingleton(beanName);

进入

org.springframework.beans.factory.support.DefaultSingletonBeanRegistry#destroySingleton

public void destroySingleton(String beanName) {
// Remove a registered singleton of the given name, if any.删除单例的bean&＃xff0c;从本地缓存中删除
removeSingleton(beanName);
// Destroy the corresponding DisposableBean instance.
DisposableBean disposableBean;
synchronized (this.disposableBeans) {
// 从本地缓存中删除
disposableBean &＃61; (DisposableBean) this.disposableBeans.remove(beanName);
}
// bean销毁的逻辑
destroyBean(beanName, disposableBean);
}

这一行

从factoryBean中创建的bean对象
bean &＃61; getObjectForBeanInstance(sharedInstance, name, beanName, mbd);

这一行

else if (mbd.isPrototype()) {
// bean定义为原型模式

这一行

原型的bean创建之前维护内存中的缓存map映射信息
beforePrototypeCreation(beanName);
// 原型的bean创建
prototypeInstance &＃61; createBean(beanName, mbd, args);

进入

org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#createBean(java.lang.String, org.springframework.beans.factory.support.RootBeanDefinition, java.lang.Object[])这一行

// bean初始化之前执行beanProccessors
Object bean &＃61; resolveBeforeInstantiation(beanName, mbdToUse);

进入

org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#resolveBeforeInstantiation

&＃64;Nullable
protected Object resolveBeforeInstantiation(String beanName, RootBeanDefinition mbd) {
Object bean &＃61; null;
if (!Boolean.FALSE.equals(mbd.beforeInstantiationResolved)) {
// Make sure bean class is actually resolved at this point.
if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {
Class targetType &＃61; determineTargetType(beanName, mbd);
if (targetType !&＃61; null) {
// 调用bean初始化前处理器
bean &＃61; applyBeanPostProcessorsBeforeInstantiation(targetType, beanName);
if (bean !&＃61; null) {
// bean初始化以后调用处理器
bean &＃61; applyBeanPostProcessorsAfterInitialization(bean, beanName);
}
}
}
mbd.beforeInstantiationResolved &＃61; (bean !&＃61; null);
}
return bean;
}

org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#createBean(java.lang.String, org.springframework.beans.factory.support.RootBeanDefinition, java.lang.Object[])

这一行

// bean创建
Object beanInstance &＃61; doCreateBean(beanName, mbdToUse, args);

org.springframework.beans.factory.support.AbstractBeanFactory#doGetBean

这一行

如果类型不一致进行类型转换
T convertedBean &＃61; getTypeConverter().convertIfNecessary(bean, requiredType);

org.springframework.beans.factory.support.DefaultListableBeanFactory#preInstantiateSingletons

这一行

for (String beanName : beanNames) {
Object singletonInstance &＃61; getSingleton(beanName);
if (singletonInstance instanceof SmartInitializingSingleton) {
final SmartInitializingSingleton smartSingleton &＃61; (SmartInitializingSingleton) singletonInstance;
if (System.getSecurityManager() !&＃61; null) {
AccessController.doPrivileged((PrivilegedAction) () -> {
// 单例bean创建完成后回调
smartSingleton.afterSingletonsInstantiated();
return null;
}, getAccessControlContext());
}
else {
smartSingleton.afterSingletonsInstantiated();
}
}
}

bean初始化以后触发回调

这一行

单例bean创建完成后回调
smartSingleton.afterSingletonsInstantiated();

org.springframework.context.support.AbstractApplicationContext#refresh

这一行 bean初始化、依赖注入

finishBeanFactoryInitialization(beanFactory);

最后

本次介绍到这里&＃xff0c;以上内容仅供参考。