FactoryBeanRegistrySupport

FactoryBeanRegistrySupport抽象类继承了DefaultSingletonBeanRegistry类，增加了对FactoryBean的处理。

类结构

常量

// 缓存factoryBean的对应关系private final Map<String, Object> factoryBeanObjectCache = new ConcurrentHashMap<>(16);

方法解析

getTypeForFactoryBean

调用factoryBean的getObjectType方法返回class类型

protected Class<?> getTypeForFactoryBean(final FactoryBean<?> factoryBean) {    try {        if (System.getSecurityManager() != null) {            return AccessController.doPrivileged((PrivilegedAction<Class<?>>)                    factoryBean::getObjectType, getAccessControlContext());        }        else {            return factoryBean.getObjectType();//调用factoryBean的getObjectType方法返回class类型。        }    }    catch (Throwable ex) {        // Thrown from the FactoryBean's getObjectType implementation.        logger.info("FactoryBean threw exception from getObjectType, despite the contract saying " +                "that it should return null if the type of its object cannot be determined yet", ex);        return null;    }}

getCachedObjectForFactoryBean

从缓存中通过制定的beanName获取FactoryBean

protected Object getCachedObjectForFactoryBean(String beanName) {    return this.factoryBeanObjectCache.get(beanName);}

getObjectFromFactoryBean

protected Object getObjectFromFactoryBean(FactoryBean<?> factory, String beanName, boolean shouldPostProcess) {    //如果是单例，且已实例化    if (factory.isSingleton() && containsSingleton(beanName)) {        //对singletonObjects加锁        synchronized (getSingletonMutex()) {            Object object = this.factoryBeanObjectCache.get(beanName);            if (object == null) {                //缓存没有                object = doGetObjectFromFactoryBean(factory, beanName);                // Only post-process and store if not put there already during getObject() call above                // (e.g. because of circular reference processing triggered by custom getBean calls)                // 预防调用上面那个方法时，有对factoryBeanObjectCache设置，所以重新取                Object alreadyThere = this.factoryBeanObjectCache.get(beanName);                if (alreadyThere != null) {                    object = alreadyThere;                }                else {                    if (shouldPostProcess) {//对该对象进行后置处理                        // 当前正在创建的bean                        if (isSingletonCurrentlyInCreation(beanName)) {                            // Temporarily return non-post-processed object, not storing it yet..                            return object;                        }                        beforeSingletonCreation(beanName);                        try {                            object = postProcessObjectFromFactoryBean(object, beanName);                        }                        catch (Throwable ex) {                            throw new BeanCreationException(beanName,                                    "Post-processing of FactoryBean's singleton object failed", ex);                        }                        finally {                            afterSingletonCreation(beanName);                        }                    }                    if (containsSingleton(beanName)) {                        //放入缓存                        this.factoryBeanObjectCache.put(beanName, object);                    }                }            }            //缓存有直接返回            return object;        }    }    else {        // 多例或者没获取过，直接获取        Object object = doGetObjectFromFactoryBean(factory, beanName);        if (shouldPostProcess) {            try {                object = postProcessObjectFromFactoryBean(object, beanName);            }            catch (Throwable ex) {                throw new BeanCreationException(beanName, "Post-processing of FactoryBean's object failed", ex);            }        }        return object;    }}

doGetObjectFromFactoryBean

调用factoryBean的getObjectType方法返回对象

private Object doGetObjectFromFactoryBean(final FactoryBean<?> factory, final String beanName)            throws BeanCreationException {    Object object;    try {        if (System.getSecurityManager() != null) {            AccessControlContext acc = getAccessControlContext();            try {                object = AccessController.doPrivileged((PrivilegedExceptionAction<Object>) factory::getObject, acc);            }            catch (PrivilegedActionException pae) {                throw pae.getException();            }        }        else {            object = factory.getObject();//调用factoryBean的getObjectType方法返回对象        }    }    catch (FactoryBeanNotInitializedException ex) {        throw new BeanCurrentlyInCreationException(beanName, ex.toString());    }    catch (Throwable ex) {        throw new BeanCreationException(beanName, "FactoryBean threw exception on object creation", ex);    }    // Do not accept a null value for a FactoryBean that's not fully    // initialized yet: Many FactoryBeans just return null then.    if (object == null) {        if (isSingletonCurrentlyInCreation(beanName)) {            throw new BeanCurrentlyInCreationException(                    beanName, "FactoryBean which is currently in creation returned null from getObject");        }        //没获取到对象，返回NullBean        object = new NullBean();    }    return object;}

postProcessObjectFromFactoryBean

预留钩子

protected Object postProcessObjectFromFactoryBean(Object object, String beanName) throws BeansException {    return object;}

getFactoryBean

返回FactoryBean

protected FactoryBean<?> getFactoryBean(String beanName, Object beanInstance) throws BeansException {    if (!(beanInstance instanceof FactoryBean)) {        throw new BeanCreationException(beanName,                "Bean instance of type [" + beanInstance.getClass() + "] is not a FactoryBean");    }    return (FactoryBean<?>) beanInstance;}

removeSingleton

除了移除DefaultSingletonBeanRegistry的对应beanName几个缓存，还要移除factoryBeanObjectCache的缓存

protected void removeSingleton(String beanName) {    synchronized (getSingletonMutex()) {        super.removeSingleton(beanName);        this.factoryBeanObjectCache.remove(beanName);    }}

clearSingletonCache

除了移除DefaultSingletonBeanRegistry的几个缓存，还要移除factoryBeanObjectCache的缓存

protected void clearSingletonCache() {    synchronized (getSingletonMutex()) {        super.clearSingletonCache();        this.factoryBeanObjectCache.clear();    }}

getAccessControlContext

获取安全作用域

protected AccessControlContext getAccessControlContext() {    return AccessController.getContext();}