SpringIOC个人笔记

@SpringBootApplication
public class SpringBootLearnApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringBootLearnApplication.class, args);
    }

}

    public static ConfigurableApplicationContext run(Class<?> primarySource, String... args) {
        return run(new Class[]{primarySource}, args);
    }

    public static ConfigurableApplicationContext run(Class<?>[] primarySources, String[] args) {
        return (new SpringApplication(primarySources)).run(args);
    }

public ConfigurableApplicationContext run(String... args) {
    // 声明一个Context容器
    ConfigurableApplicationContext context = null;
    // 获取监听器
    SpringApplicationRunListeners listeners = getRunListeners(args);
    // 调用监听器的启动
    listeners.starting();

    try {
        // 创建并配置Environment（这个过程会加载application配置文件）
        ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments);
        // 根据应用类型创建对应的Context容器
        context = createApplicationContext();

        // 刷新Context容器之前的准备
        prepareContext(context, environment, listeners, applicationArguments, printedBanner);
        // 刷新Context容器
        refreshContext(context);
        // 刷新Context容器之后处理
        afterRefresh(context, applicationArguments);

        // Context容器refresh完毕发布
        listeners.started(context);

        // 触发Context容器refresh完以后的执行
        callRunners(context, applicationArguments);
    } catch (Throwable ex) {}

    try {
        // Context启动完毕，Runner运行完毕发布
        listeners.running(context);
    } catch (Throwable ex) {}

    return context;
}

    private void refreshContext(ConfigurableApplicationContext context) {
        if (this.registerShutdownHook) {
            try {
                context.registerShutdownHook();
            } catch (AccessControlException var3) {
            }
        }

        this.refresh((ApplicationContext)context);
    }

    @Deprecated
    protected void refresh(ApplicationContext applicationContext) {
        Assert.isInstanceOf(ConfigurableApplicationContext.class, applicationContext);
        this.refresh((ConfigurableApplicationContext)applicationContext);
    }

    protected void refresh(ConfigurableApplicationContext applicationContext) {
        applicationContext.refresh();
    }

 public void refresh() throws BeansException, IllegalStateException {
        synchronized(this.startupShutdownMonitor) {
             // 刷新前准备，设置flag、时间，初始化properties等
            this.prepareRefresh();
            // 获取ApplicationContext中组合的BeanFactory
            ConfigurableListableBeanFactory beanFactory = this.obtainFreshBeanFactory();
            // 设置类加载器，添加后置处理器等准备
            this.prepareBeanFactory(beanFactory);

            try {
                // 供子类实现的后置处理
                this.postProcessBeanFactory(beanFactory);
                 // 调用Bean工厂的后置处理器
                this.invokeBeanFactoryPostProcessors(beanFactory);
                // 注册Bean的后置处理器
                this.registerBeanPostProcessors(beanFactory);
                 // 初始化消息源
                this.initMessageSource();
                 // 初始化事件广播
                this.initApplicationEventMulticaster();
                // 供之类实现的，初始化特殊的Bean
                this.onRefresh();
                // 注册监听器
                this.registerListeners();
                // 实例化所有的(non-lazy-init)单例Bean
                this.finishBeanFactoryInitialization(beanFactory);
                // 发布刷新完毕事件
                this.finishRefresh();
            } catch (BeansException var9) {
                if (this.logger.isWarnEnabled()) {
                    this.logger.warn("Exception encountered during context initialization - cancelling refresh attempt: " + var9);
                }

                this.destroyBeans();
                this.cancelRefresh(var9);
                throw var9;
            } finally {
                this.resetCommonCaches();
            }

        }
    }

protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
 PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory,this.getBeanFactoryPostProcessors();
//......
    }

public static void invokeBeanFactoryPostProcessors(
        ConfigurableListableBeanFactory beanFactory, 
        List<BeanFactoryPostProcessor> beanFactoryPostProcessors
        ) {
    // 
    if (beanFactory instanceof BeanDefinitionRegistry) {
        //
        while (reiterate) {
            // 调用BeanDefinition注册的后置处理器
            invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
            // 
        }
        //
    } else {
        // 
    }
    //
}

private static void invokeBeanDefinitionRegistryPostProcessors(
            Collection<? extends BeanDefinitionRegistryPostProcessor> postProcessors, 
            BeanDefinitionRegistry registry
            ) {
    for (BeanDefinitionRegistryPostProcessor postProcessor : postProcessors) {
        postProcessor.postProcessBeanDefinitionRegistry(registry);
    }
}

public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) {
    List<BeanDefinitionHolder> configCandidates = new ArrayList<>();
    String[] candidateNames = registry.getBeanDefinitionNames();

    for (String beanName : candidateNames) {
        BeanDefinition beanDef = registry.getBeanDefinition(beanName);
        if (ConfigurationClassUtils.isFullConfigurationClass(beanDef) ||
                ConfigurationClassUtils.isLiteConfigurationClass(beanDef)) {
            // 
        } else if (ConfigurationClassUtils.checkConfigurationClassCandidate(beanDef, this.metadataReaderFactory)) {
            // 默认仅有主类被添加
            configCandidates.add(new BeanDefinitionHolder(beanDef, beanName));
        }
    }

    //

    // 解析被 @Configuration 注解的类
    ConfigurationClassParser parser = new ConfigurationClassParser(
            this.metadataReaderFactory, 
            this.problemReporter, 
            this.environment,
            this.resourceLoader, 
            this.componentScanBeanNameGenerator, 
            registry);

    Set<BeanDefinitionHolder> candidates = new LinkedHashSet<>(configCandidates);
    // 
    do {
        // 解析的核心方法
        parser.parse(candidates);
        parser.validate();

        // 

        candidates.clear();
        // 
    } while (!candidates.isEmpty());
    // 
}

public void parse(Set<BeanDefinitionHolder> configCandidates) {
    for (BeanDefinitionHolder holder : configCandidates) {
        BeanDefinition bd = holder.getBeanDefinition();
        try {
            if (bd instanceof AnnotatedBeanDefinition) {
                // 主类的解析将从这里进入
                parse(((AnnotatedBeanDefinition) bd).getMetadata(), holder.getBeanName());
            } else if (bd instanceof AbstractBeanDefinition && ((AbstractBeanDefinition) bd).hasBeanClass()) {
                parse(((AbstractBeanDefinition) bd).getBeanClass(), holder.getBeanName());
            } else {
                parse(bd.getBeanClassName(), holder.getBeanName());
            }
        } catch (BeanDefinitionStoreException ex) {}
          catch (Throwable ex) {}
    }

    this.deferredImportSelectorHandler.process();
}

protected final void parse(AnnotationMetadata metadata, String beanName) throws IOException {
    processConfigurationClass(new ConfigurationClass(metadata, beanName));
}

protected void processConfigurationClass(ConfigurationClass configClass) throws IOException {
    // 

    // 由main方法所在的主类开始，向超类逐层向上递归解析
    SourceClass sourceClass = asSourceClass(configClass);
    do {
        // 这里包含了解析单个配置类的核心逻辑
        sourceClass = doProcessConfigurationClass(configClass, sourceClass);
    } while (sourceClass != null);

    // 
}

protected final SourceClass doProcessConfigurationClass(ConfigurationClass configClass, SourceClass sourceClass)
        throws IOException {
    //

    // 处理@ComponentScan注解
    Set<AnnotationAttributes> componentScans = AnnotationConfigUtils.attributesForRepeatable(sourceClass.getMetadata(), ComponentScans.class, ComponentScan.class);
    if (!componentScans.isEmpty() &&
            !this.conditionEvaluator.shouldSkip(sourceClass.getMetadata(), ConfigurationPhase.REGISTER_BEAN)) {
        // 遍历@ComponentScan的属性值
        for (AnnotationAttributes componentScan : componentScans) {
            // 解析扫描
            Set<BeanDefinitionHolder> scannedBeanDefinitions = this.componentScanParser.parse(componentScan, sourceClass.getMetadata().getClassName());
            // 
        }
    }

    // 

    // 判断是否有超类
    if (sourceClass.getMetadata().hasSuperClass()) {
        String superclass = sourceClass.getMetadata().getSuperClassName();
        if (superclass != null && !superclass.startsWith("java") &&
                !this.knownSuperclasses.containsKey(superclass)) {
            this.knownSuperclasses.put(superclass, configClass);
            // 返回待解析的超类
            return sourceClass.getSuperClass();
        }
    }

    // 没有超类，则解析完毕
    return null;
}

@Override
public Object getBean(String name) throws BeansException {
    //
    return getBeanFactory().getBean(name);
}

@Override
public Object getBean(String name) throws BeansException {
    return doGetBean(name, null, null, false);
}

protected <T> T doGetBean(
        final String name, 
        @Nullable final Class<T> requiredType,
        @Nullable final Object[] args, 
        boolean typeCheckOnly) throws BeansException {

    final String beanName = transformedBeanName(name);
    Object bean;

    // 如果拿到已经注册的单例Bean，直接返回结果
    Object sharedInstance = getSingleton(beanName);
    if (sharedInstance != null && args == null) {
        //
        bean = getObjectForBeanInstance(sharedInstance, name, beanName, null);
    } else {

        //

        try {
            final RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);

            //

            // 创建单例
            if (mbd.isSingleton()) {
                // 回调创建
                sharedInstance = getSingleton(beanName, () -> {
                    try {
                        return createBean(beanName, mbd, args);
                    } catch (BeansException ex) {
                        //
                    }
                });
                bean = getObjectForBeanInstance(sharedInstance, name, beanName, mbd);
            } else if (mbd.isPrototype()) {
                Object prototypeInstance = null;
                try {
                    beforePrototypeCreation(beanName);
                    // 每次创建
                    prototypeInstance = createBean(beanName, mbd, args);
                } finally {
                    //
                }
                bean = getObjectForBeanInstance(prototypeInstance, name, beanName, mbd);
            } else {
                //
            }
        } catch (BeansException ex) {
            //
        }
    }
    //

    return (T) bean;
}

private final Map<String, Object> singletonObjects = new ConcurrentHashMap<>(256);

public Object getSingleton(String beanName, ObjectFactory<?> singletonFactory) {
    // 内置锁控制
    synchronized (this.singletonObjects) {
        // 双重校验
        Object singletonObject = this.singletonObjects.get(beanName);
        if (singletonObject == null) {
            //

            boolean newSingleton = false;
            //
            try {
                // 回调创建Bean
                singletonObject = singletonFactory.getObject();
                newSingleton = true;
            }
            catch (IllegalStateException ex) {
                //
            }
            catch (BeanCreationException ex) {
                //
            } finally {
                //
            }
            if (newSingleton) {
                // 添加单例到缓存中
                addSingleton(beanName, singletonObject);
            }
        }
        return singletonObject;
    }
}

@Override
protected Object createBean(
        String beanName, 
        RootBeanDefinition mbd, 
        @Nullable Object[] args) throws BeanCreationException {
    //
    RootBeanDefinition mbdToUse = mbd;

    //

    try {
        // 创建Bean实例
        Object beanInstance = doCreateBean(beanName, mbdToUse, args);
        //
        return beanInstance;
    } catch (BeanCreationException | ImplicitlyAppearedSingletonException ex) {
        //
    } catch (Throwable ex) {
        //
    }
}

protected Object doCreateBean(
        final String beanName, 
        final RootBeanDefinition mbd, 
        final @Nullable Object[] args) throws BeanCreationException {

    // 创建Bean实例对象
    BeanWrapper instanceWrapper = null;
    //
    if (instanceWrapper == null) {
        instanceWrapper = createBeanInstance(beanName, mbd, args);
    }
    //
    try {
        // 自动注入
        populateBean(beanName, mbd, instanceWrapper);
        //
    } catch (Throwable ex) {
        //
    }
    //

    return exposedObject;
}

protected void populateBean(String beanName, RootBeanDefinition mbd, @Nullable BeanWrapper bw) {
    // 

    // 获取待注入的property，配置文件中配置的<property>将在这里被处理
    PropertyValues pvs = (mbd.hasPropertyValues() ? mbd.getPropertyValues() : null);

    // 按照名字或者类型获取属性，这里会进行递归
    if (mbd.getResolvedAutowireMode() == AUTOWIRE_BY_NAME || mbd.getResolvedAutowireMode() == AUTOWIRE_BY_TYPE) {
        MutablePropertyValues newPvs = new MutablePropertyValues(pvs);
        // 按照名字获取属性
        if (mbd.getResolvedAutowireMode() == AUTOWIRE_BY_NAME) {
            autowireByName(beanName, mbd, bw, newPvs);
        }
        // 按照类型获取属性
        if (mbd.getResolvedAutowireMode() == AUTOWIRE_BY_TYPE) {
            autowireByType(beanName, mbd, bw, newPvs);
        }
        pvs = newPvs;
    }

    boolean hasInstAwareBpps = hasInstantiationAwareBeanPostProcessors();
    boolean needsDepCheck = (mbd.getDependencyCheck() != AbstractBeanDefinition.DEPENDENCY_CHECK_NONE);

    PropertyDescriptor[] filteredPds = null;
    if (hasInstAwareBpps) {
        if (pvs == null) {
            pvs = mbd.getPropertyValues();
        }
        for (BeanPostProcessor bp : getBeanPostProcessors()) {
            if (bp instanceof InstantiationAwareBeanPostProcessor) {
                InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
                PropertyValues pvsToUse = ibp.postProcessProperties(pvs, bw.getWrappedInstance(), beanName);
                if (pvsToUse == null) {
                    if (filteredPds == null) {
                        filteredPds = filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching);
                    }
                    // 后置处理器处理@Autowired @Resource等注解
                    pvsToUse = ibp.postProcessPropertyValues(pvs, filteredPds, bw.getWrappedInstance(), beanName);
                    if (pvsToUse == null) {
                        return;
                    }
                }
                pvs = pvsToUse;
            }
        }
    }
    // 注入<property>属性
    if (pvs != null) {
        applyPropertyValues(beanName, mbd, bw, pvs);
    }
}

public PropertyValues postProcessPropertyValues(
        PropertyValues pvs, PropertyDescriptor[] pds, Object bean, String beanName) {

    return postProcessProperties(pvs, bean, beanName);
}

public PropertyValues postProcessProperties(PropertyValues pvs, Object bean, String beanName) {
    // 获取当前Bean的元数据，将包含@Autowired等注解的标注的待注入元素
    InjectionMetadata metadata = findAutowiringMetadata(beanName, bean.getClass(), pvs);
    try {
        // 注入元素
        metadata.inject(bean, beanName, pvs);
    }
    catch (BeanCreationException ex) {
        throw ex;
    }
    catch (Throwable ex) {
        throw new BeanCreationException(beanName, "Injection of autowired dependencies failed", ex);
    }
    return pvs;
}

private InjectionMetadata findAutowiringMetadata(String beanName, Class<?> clazz, @Nullable PropertyValues pvs) {
.
    String cacheKey = (StringUtils.hasLength(beanName) ? beanName : clazz.getName());

    InjectionMetadata metadata = this.injectionMetadataCache.get(cacheKey);
    if (InjectionMetadata.needsRefresh(metadata, clazz)) {
        synchronized (this.injectionMetadataCache) {
            metadata = this.injectionMetadataCache.get(cacheKey);
            if (InjectionMetadata.needsRefresh(metadata, clazz)) {
                if (metadata != null) {
                    metadata.clear(pvs);
                }
                // 构造元数据
                metadata = buildAutowiringMetadata(clazz);
                this.injectionMetadataCache.put(cacheKey, metadata);
            }
        }
    }
    return metadata;
}

protected void inject(Object target, @Nullable String requestingBeanName, @Nullable PropertyValues pvs)
        throws Throwable {

    if (this.isField) {
        Field field = (Field) this.member;
        ReflectionUtils.makeAccessible(field);
        // 反射设置值，这里的取值会对依赖进行递归处理
        field.set(target, getResourceToInject(target, requestingBeanName));
    } else {
        // 省略
    }
}

private InjectionMetadata buildResourceMetadata(final Class<?> clazz) {
    List<InjectionMetadata.InjectedElement> elements = new ArrayList<>();
    Class<?> targetClass = clazz;

    do {
        final List<InjectionMetadata.InjectedElement> currElements = new ArrayList<>();

        ReflectionUtils.doWithLocalFields(targetClass, field -> {
            if (webServiceRefClass != null && field.isAnnotationPresent(webServiceRefClass)) {
                //
            }
            else if (ejbRefClass != null && field.isAnnotationPresent(ejbRefClass)) {
                //
            }
            // 如果注解了@Resource
            else if (field.isAnnotationPresent(Resource.class)) {
                //
                if (!this.ignoredResourceTypes.contains(field.getType().getName())) {
                    // 添加element
                    currElements.add(new ResourceElement(field, field, null));
                }
            }
        });

        //

        elements.addAll(0, currElements);
        // 向父类递归
        targetClass = targetClass.getSuperclass();
    }
    while (targetClass != null && targetClass != Object.class);

    return new InjectionMetadata(clazz, elements);
}