Spring源码解析 Bean属性填充

Object exposedObject = bean;
try {
  populateBean(beanName, mbd, instanceWrapper);
  exposedObject = initializeBean(beanName, exposedObject, mbd);
}

for (BeanPostProcessor bp : getBeanPostProcessors()) {
  if (bp instanceof InstantiationAwareBeanPostProcessor) {
    InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
    pvs = ibp.postProcessPropertyValues(pvs, filteredPds, bw.getWrappedInstance(), beanName);
    if (pvs == null) {
      return;
    }
  }
}

public PropertyValues postProcessPropertyValues(
  PropertyValues pvs, PropertyDescriptor[] pds, Object bean, String beanName) throws BeanCreationException {
  InjectionMetadata metadata = findAutowiringMetadata(beanName, bean.getClass(), pvs);
  try {
    metadata.inject(bean, beanName, pvs);
  }
 //异常处理代码省略...
  return pvs;
}

private final Collection injectedElements;

private InjectionMetadata findAutowiringMetadata(String beanName, Class clazz, @Nullable PropertyValues pvs) {
 String cacheKey = (StringUtils.hasLength(beanName) ? beanName : clazz.getName());
 InjectionMetadata metadata = this.injectionMetadataCache.get(cacheKey);
  //省略非重要代码...
 return metadata;
}

protected void inject(Object bean, @Nullable String beanName, @Nullable PropertyValues pvs) throws Throwable {
      Field field = (Field) this.member;
      Object value;
      if (this.cached) {
        value = resolvedCachedArgument(beanName, this.cachedFieldValue);
      }
      else {
        DependencyDescriptor desc = new DependencyDescriptor(field, this.required);
        desc.setContainingClass(bean.getClass());
        Set autowiredBeanNames = new LinkedHashSet<>(1);
        Assert.state(beanFactory != null, "No BeanFactory available");
        TypeConverter typeCOnverter= beanFactory.getTypeConverter();
        try {//用beanFactory解决依赖
          value = beanFactory.resolveDependency(desc, beanName, autowiredBeanNames, typeConverter);
        }
   //后面代码省略...

public Object doResolveDependency(DependencyDescriptor descriptor, @Nullable String beanName,
    @Nullable Set autowiredBeanNames, @Nullable TypeConverter typeConverter) throws BeansException {
  InjectionPoint previousInjectiOnPoint= ConstructorResolver.setCurrentInjectionPoint(descriptor);
  try {
    Object shortcut = descriptor.resolveShortcut(this);
    if (shortcut != null) {
      return shortcut;
    }
    //依赖的属性值的类型
    Class type = descriptor.getDependencyType();
    Object value = getAutowireCandidateResolver().getSuggestedValue(descriptor);
    if (value != null) {
      if (value instanceof String) {
        String strVal = resolveEmbeddedValue((String) value);
        BeanDefinition bd = (beanName != null && containsBean(beanName) ? getMergedBeanDefinition(beanName) : null);
        value = evaluateBeanDefinitionString(strVal, bd);
      }
      TypeConverter cOnverter= (typeConverter != null ? typeConverter : getTypeConverter());
      return (descriptor.getField() != null ?
          converter.convertIfNecessary(value, type, descriptor.getField()) :
          converter.convertIfNecessary(value, type, descriptor.getMethodParameter()));
    }

    Object multipleBeans = resolveMultipleBeans(descriptor, beanName, autowiredBeanNames, typeConverter);
    if (multipleBeans != null) {
      return multipleBeans;
    }
    //把匹配的值和类型拿出来，放到一个map中
    Map matchingBeans = findAutowireCandidates(beanName, type, descriptor);
    if (matchingBeans.isEmpty()) {
      if (isRequired(descriptor)) {
        raiseNoMatchingBeanFound(type, descriptor.getResolvableType(), descriptor);
      }
      return null;
    }

    String autowiredBeanName;
    Object instanceCandidate;
    //如果有超过一个匹配的，可能会有错误
    if (matchingBeans.size() > 1) {
      autowiredBeanName = determineAutowireCandidate(matchingBeans, descriptor);
      if (autowiredBeanName == null) {
        if (isRequired(descriptor) || !indicatesMultipleBeans(type)) {
          return descriptor.resolveNotUnique(type, matchingBeans);
        }
        else {
          return null;
        }
      }
      instanceCandidate = matchingBeans.get(autowiredBeanName);
    }
    else {
      Map.Entry entry = matchingBeans.entrySet().iterator().next();
      autowiredBeanName = entry.getKey();
      instanceCandidate = entry.getValue();
    }

    if (autowiredBeanNames != null) {
      //把找到的bean的名字放到set中
      autowiredBeanNames.add(autowiredBeanName);
    }
    if (instanceCandidate instanceof Class) {
      // 实际获取注入的bean
      instanceCandidate = descriptor.resolveCandidate(autowiredBeanName, type, this);
    }
    Object result = instanceCandidate;
    if (result instanceof NullBean) {
      if (isRequired(descriptor)) {
        raiseNoMatchingBeanFound(type, descriptor.getResolvableType(), descriptor);
      }
      result = null;
    }
    if (!ClassUtils.isAssignableValue(type, result)) {
      throw new BeanNotOfRequiredTypeException(autowiredBeanName, type, instanceCandidate.getClass());
    }
    return result;
  }
  finally {
    ConstructorResolver.setCurrentInjectionPoint(previousInjectionPoint);
  }
}

ReflectionUtils.makeAccessible(field);
field.set(bean, value);

protected Object initializeBean(final String beanName, final Object bean, @Nullable RootBeanDefinition mbd) {
  if (System.getSecurityManager() != null) {
    AccessController.doPrivileged((PrivilegedAction) () -> {
      invokeAwareMethods(beanName, bean);
      return null;
    }, getAccessControlContext());
  }
  else {
    //若bean实现了BeanNameAware、BeanClassLoaderAware、BeanFactoryAware接口，执行回调方法
    invokeAwareMethods(beanName, bean);
  }

  Object wrappedBean = bean;
  if (mbd == null || !mbd.isSynthetic()) {
    //执行所有后置处理器的before方法
    wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);
  }

  try {
    //执行bean生命周期回调中的init-method
    //若bean实现了InitializingBean接口，执行afterPropertiesSet方法
    invokeInitMethods(beanName, wrappedBean, mbd);
  }
  catch (Throwable ex) {
    throw new BeanCreationException(
        (mbd != null ? mbd.getResourceDescription() : null),
        beanName, "Invocation of init method failed", ex);
  }
  if (mbd == null || !mbd.isSynthetic()) {
    //执行所有后置处理器的after方法
    wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
  }

  return wrappedBean;
}