手写简易版Spring IOC容器05【学习】

拓展bean的作用域以及实现FactoryBean.
在之前实现的bean中获取bean默认都是单例的也就是只创建一个bean对象，这次拓展beanDefinition添加单例实现和prototype实现

bean作用域

beanDefinition添加字段

String SCOPE_SINGLETON = ConfigurableBeanFactory.SCOPE_SINGLETON;String SCOPE_PROTOTYPE = ConfigurableBeanFactory.SCOPE_PROTOTYPE;private boolean singleton = true;private boolean prototype = false;public void setScope(String scope){this.scope = scope;this.singleton = SCOPE_SINGLETON.equals(scope);this.prototype = SCOPE_PROTOTYPE.equals(scope);
}

registry bean时添加bean的scope

// 如果配置了scope设置scope..
if(StrUtil.isNotEmpty(beanScope)){beanDefinition.setScope(beanScope);
}

创建bean时进行判断

@Override
protected Object createBean(String beanName, BeanDefinition beanDefinition, Object[] args) throws BeansException {Object bean = null;try {bean = createBeanInstance(beanDefinition, beanName, args);// 给 Bean 填充属性applyPropertyValues(beanName, bean, beanDefinition);// 执行 Bean 的初始化方法和 BeanPostProcessor 的前置和后置处理方法bean = initializeBean(beanName, bean, beanDefinition);} catch (Exception e) {throw new BeansException("Instantiation of bean failed", e);}// 注册实现了 DisposableBean 接口的 Bean 对象registerDisposableBeanIfNecessary(beanName, bean, beanDefinition);// 判断 SCOPE_SINGLETON、SCOPE_PROTOTYPEif(beanDefinition.isSingleton()){addSingleton(beanName, bean);}// 如果不是单例则直接创建对象返回return bean;
}

扩展FactoryBean

factoryBean本质也是一个bean对象，区别于普通的bean，它生成bean。

FactoryBean接口

public interface FactoryBean<T> {T getObject() throws Exception;Class<?> getObjectType();boolean isSingleton();}

FactoryBeanRegistrySupport FactoryBean注册

存放的都是通过FactoryBean 创建的对象

public abstract class FactoryBeanRegistrySupport extends DefaultSingletonBeanRegistry{private final Map<String, Object> factoryBeanObjectCache = new ConcurrentHashMap<String, Object>();// 从缓存中获取protected Object getCachedObjectForFactoryBean(String beanName){Object object = this.factoryBeanObjectCache.get(beanName);return (object != NULL_OBJECT ? object : null);}// 从FactoryBean中获取.protected Object getObjectFromFactoryBean(FactoryBean factory, String beanName) {// 判断当前factory是单例吗if (factory.isSingleton()) {Object object = this.factoryBeanObjectCache.get(beanName);if (object == null) {object = doGetObjectFromFactoryBean(factory, beanName);this.factoryBeanObjectCache.put(beanName, (object != null ? object : NULL_OBJECT));}return (object != NULL_OBJECT ? object : null);}else{return doGetObjectFromFactoryBean(factory, beanName);}}private Object doGetObjectFromFactoryBean(final FactoryBean factory, final String beanName){try {return factory.getObject();}catch (Exception e){throw new BeansException("FactoryBean threw exception on object[" + beanName + "] creation", e);}}}

AbstractBeanFactory.GetBean方法

getBean时首先拿到当前bean对象判断是FactoryBean对象吗？如果是需要从上一步中FactoryBeanRegistry的map中来获取对象。 如果不是先创建FactoryBean对象还是继续去FactoryBean中去获取。

protected <T> T doGetBean(final String name, final Object[] args) {Object sharedInstance = getSingleton(name);if (sharedInstance != null) {// 如果是 FactoryBean，则需要调用 FactoryBean#getObjectreturn (T) getObjectForBeanInstance(sharedInstance, name);}BeanDefinition beanDefinition = getBeanDefinition(name);Object bean = createBean(name, beanDefinition, args);return (T) getObjectForBeanInstance(bean, name);
}

getObjectForBeanInstance

如果拿到的不是FactoryBean类型的对象则直接返回

private Object getObjectForBeanInstance(Object beanInstance, String beanName) {// 如果当前拿的对象不是FactoryBean 返回单例中存放的bean对象if (!(beanInstance instanceof FactoryBean)) {return beanInstance;}// 否则去factoryBean的缓存中去拿对象.Object object = getCachedObjectForFactoryBean(beanName);// 缓存中没有则通过FactoryBean去创建这个对象if(object == null){FactoryBean<?> factoryBean = (FactoryBean<?>) beanInstance;object = getObjectFromFactoryBean(factoryBean,beanName);}return object;
}

getObjectFromFactoryBean

protected Object getObjectFromFactoryBean(FactoryBean factory, String beanName) {// 判断当前factory是单例吗if (factory.isSingleton()) {Object object = this.factoryBeanObjectCache.get(beanName);if (object == null) {object = doGetObjectFromFactoryBean(factory, beanName);this.factoryBeanObjectCache.put(beanName, (object != null ? object : NULL_OBJECT));}return (object != NULL_OBJECT ? object : null);}else{return doGetObjectFromFactoryBean(factory, beanName);}
}