本來昨天在看 spring frame的八股， 看到了IOC部分，但是實在看不懂是什么東西，講是講源碼部分，但又不完全講，我想著那我要不自己看一下源碼

這是我畫的Bean Factory的大致關系圖

刪去了bean別名管理接口（AliasRegistry）和bean定義接口（BeanDefinitionRegistry）避免復雜理解

BeanFactory有三個子類ListableBeanFactory ，HierarchicalBeanFactory，ConfigurableBeanFactory ，AutowireCapableBeanFactory 。

我們先來看看BeanFactory 只實現了IOC 容器的基本行為規范，好比是讓需求方提出對目標的需求。

public interface BeanFactory {
//與FactoryBean創建的bean區分開來, 若命名的bean是FactoryBean，
//則獲取將返回Factory，而不是Factory返回的實例。
    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);
}

ListableBeanFactory 定義了Factory Bean的可枚舉性，適用于批量操作 bean 的場景

public interface ListableBeanFactory extends BeanFactory {
    boolean containsBeanDefinition(String var1);

    int getBeanDefinitionCount();

    String[] getBeanDefinitionNames();

    <T> ObjectProvider<T> getBeanProvider(Class<T> var1, boolean var2);

    <T> ObjectProvider<T> getBeanProvider(ResolvableType var1, boolean var2);

    String[] getBeanNamesForType(ResolvableType var1);

    String[] getBeanNamesForType(ResolvableType var1, boolean var2, boolean var3);

    String[] getBeanNamesForType(@Nullable Class<?> var1);

    String[] getBeanNamesForType(@Nullable Class<?> var1, boolean var2, boolean var3);

    <T> Map<String, T> getBeansOfType(@Nullable Class<T> var1) throws BeansException;

    <T> Map<String, T> getBeansOfType(@Nullable Class<T> var1, boolean var2, boolean var3) throws BeansException;

    String[] getBeanNamesForAnnotation(Class<? extends Annotation> var1);

    Map<String, Object> getBeansWithAnnotation(Class<? extends Annotation> var1) throws BeansException;

    @Nullable
    <A extends Annotation> A findAnnotationOnBean(String var1, Class<A> var2) throws NoSuchBeanDefinitionException;

    @Nullable
    <A extends Annotation> A findAnnotationOnBean(String var1, Class<A> var2, boolean var3) throws NoSuchBeanDefinitionException;
}

HierarchicalBeanFactory 定義了Bean Factory的分層能力

之前還不知道Bean Factory可以有父子容器區分
與繼承相似，子類可以調用父類的方法。父類不能調用子類的方法

Spring MVC 有以下分層

• 根上下文（ContextLoaderListener 或 Spring Boot 創建）作為父容器。

如服務層、數據訪問層和基礎設施 bean（DataSource）。

• DispatcherServlet 的上下文作為子容器。

定義 Web 層特定 bean，如控制器、HandlerMapping 等。

public interface HierarchicalBeanFactory extends BeanFactory {
    @Nullable
    BeanFactory getParentBeanFactory();

    boolean containsLocalBean(String var1);
}

ConfigurableBeanFactory 定義了自定義Bean工廠的能力 ， 自定義類加載器、beany定義、作用域、依賴關系。

public interface ConfigurableBeanFactory extends HierarchicalBeanFactory, SingletonBeanRegistry {
    // 自定義類加載器
    void setBeanClassLoader(@Nullable ClassLoader var1);
    @Nullable
    ClassLoader getBeanClassLoader();
    void setTempClassLoader(@Nullable ClassLoader var1);
    @Nullable
    ClassLoader getTempClassLoader();

    // bean 定義
    void setCacheBeanMetadata(boolean var1);
    boolean isCacheBeanMetadata();
    BeanDefinition getMergedBeanDefinition(String var1) throws NoSuchBeanDefinitionException;
    boolean isFactoryBean(String var1) throws NoSuchBeanDefinitionException;

    // 作用域
    void registerScope(String var1, Scope var2);
    String[] getRegisteredScopeNames();
    @Nullable
    Scope getRegisteredScope(String var1);

    // 依賴關系
    void registerDependentBean(String var1, String var2);
    String[] getDependentBeans(String var1);
    String[] getDependenciesForBean(String var1);
    
    ......
    ......
}

AutowireCapableBeanFactory 實現了Bean自動裝配能力

public interface AutowireCapableBeanFactory extends BeanFactory {
    int AUTOWIRE_NO = 0;
    int AUTOWIRE_BY_NAME = 1;
    int AUTOWIRE_BY_TYPE = 2;
    int AUTOWIRE_CONSTRUCTOR = 3;
    /** @deprecated */
    @Deprecated
    int AUTOWIRE_AUTODETECT = 4;
    String ORIGINAL_INSTANCE_SUFFIX = ".ORIGINAL";

    <T> T createBean(Class<T> var1) throws BeansException;

    void autowireBean(Object var1) throws BeansException;

    Object configureBean(Object var1, String var2) throws BeansException;

    Object createBean(Class<?> var1, int var2, boolean var3) throws BeansException;

    Object autowire(Class<?> var1, int var2, boolean var3) throws BeansException;

    void autowireBeanProperties(Object var1, int var2, boolean var3) throws BeansException;

    void applyBeanPropertyValues(Object var1, String var2) throws BeansException;

    Object initializeBean(Object var1, String var2) throws BeansException;

    Object applyBeanPostProcessorsBeforeInitialization(Object var1, String var2) throws BeansException;

    Object applyBeanPostProcessorsAfterInitialization(Object var1, String var2) throws BeansException;

    void destroyBean(Object var1);

    <T> NamedBeanHolder<T> resolveNamedBean(Class<T> var1) throws BeansException;

    Object resolveBeanByName(String var1, DependencyDescriptor var2) throws BeansException;

    @Nullable
    Object resolveDependency(DependencyDescriptor var1, @Nullable String var2) throws BeansException;

    @Nullable
    Object resolveDependency(DependencyDescriptor var1, @Nullable String var2, @Nullable Set<String> var3, @Nullable TypeConverter var4) throws BeansException;
}

看完了這些接口類和接口方法，對IOC容器有了更擴展一些的理解

其實源碼還是挺容易看的，先通過一個類向上找到基類，再往下看詳細的接口類，實現類。 對其有一個全局的理解