Spring IOC源码解析（09）BeanFactoryUti
2020-06-12 本文已影响0人
juconcurrent
前言
BeanFactoryUtils作为bean工厂操作的工具类，包含了很多的方法。对这些方法的理解，将加深我们后续对BeanFactory实现的分析。
源码解析
/**
* Convenience methods operating on bean factories, in particular
* on the {@link ListableBeanFactory} interface.
*
* <p>Returns bean counts, bean names or bean instances,
* taking into account the nesting hierarchy of a bean factory
* (which the methods defined on the ListableBeanFactory interface don't,
* in contrast to the methods defined on the BeanFactory interface).
*
* @author Rod Johnson
* @author Juergen Hoeller
* @author Chris Beams
* @since 04.07.2003
*/
public abstract class BeanFactoryUtils {
/**
* bean名称的分隔符，当类名或父类名不是唯一时，将通过追加后缀`#1`或`#2`的方式来使得bean名称变得唯一。
* 通常在内部bean的时候使用。
* Separator for generated bean names. If a class name or parent name is not
* unique, "#1", "#2" etc will be appended, until the name becomes unique.
*/
public static final String GENERATED_BEAN_NAME_SEPARATOR = "#";
/**
* 缓存map，工厂bean名称 -> 剥离掉&前缀后的bean名称
* 即：工厂bean创建的bean的名称
* Cache from name with factory bean prefix to stripped name without dereference.
* @since 5.1
* @see BeanFactory#FACTORY_BEAN_PREFIX
*/
private static final Map<String, String> transformedBeanNameCache = new ConcurrentHashMap<>();
/**
* 根据名称判断是否是一个工厂bean的名称
* Return whether the given name is a factory dereference
* (beginning with the factory dereference prefix).
* @param name the name of the bean
* @return whether the given name is a factory dereference
* @see BeanFactory#FACTORY_BEAN_PREFIX
*/
public static boolean isFactoryDereference(@Nullable String name) {
return (name != null && name.startsWith(BeanFactory.FACTORY_BEAN_PREFIX));
}
/**
* 将带有&的所有前缀全部去掉，也就是实际工厂bean创建后的bean的名称
* 这儿使用了循环遍历，是因为工厂bean创建出来的bean也可能是另外一个工厂bean，以此类推
* Return the actual bean name, stripping out the factory dereference
* prefix (if any, also stripping repeated factory prefixes if found).
* @param name the name of the bean
* @return the transformed name
* @see BeanFactory#FACTORY_BEAN_PREFIX
*/
public static String transformedBeanName(String name) {
Assert.notNull(name, "'name' must not be null");
if (!name.startsWith(BeanFactory.FACTORY_BEAN_PREFIX)) {
return name;
}
return transformedBeanNameCache.computeIfAbsent(name, beanName -> {
do {
beanName = beanName.substring(BeanFactory.FACTORY_BEAN_PREFIX.length());
}
while (beanName.startsWith(BeanFactory.FACTORY_BEAN_PREFIX));
return beanName;
});
}
/**
* 判断是否内部生成的bean名称
* Return whether the given name is a bean name which has been generated
* by the default naming strategy (containing a "#..." part).
* @param name the name of the bean
* @return whether the given name is a generated bean name
* @see #GENERATED_BEAN_NAME_SEPARATOR
* @see org.springframework.beans.factory.support.BeanDefinitionReaderUtils#generateBeanName
* @see org.springframework.beans.factory.support.DefaultBeanNameGenerator
*/
public static boolean isGeneratedBeanName(@Nullable String name) {
return (name != null && name.contains(GENERATED_BEAN_NAME_SEPARATOR));
}
/**
* 获取内部bean所在的外部bean
* Extract the "raw" bean name from the given (potentially generated) bean name,
* excluding any "#..." suffixes which might have been added for uniqueness.
* @param name the potentially generated bean name
* @return the raw bean name
* @see #GENERATED_BEAN_NAME_SEPARATOR
*/
public static String originalBeanName(String name) {
Assert.notNull(name, "'name' must not be null");
int separatorIndex = name.indexOf(GENERATED_BEAN_NAME_SEPARATOR);
return (separatorIndex != -1 ? name.substring(0, separatorIndex) : name);
}
// Retrieval of bean names
/**
* 获取包含祖先在内的所有bean的数量
* Count all beans in any hierarchy in which this factory participates.
* Includes counts of ancestor bean factories.
* <p>Beans that are "overridden" (specified in a descendant factory
* with the same name) are only counted once.
* @param lbf the bean factory
* @return count of beans including those defined in ancestor factories
* @see #beanNamesIncludingAncestors
*/
public static int countBeansIncludingAncestors(ListableBeanFactory lbf) {
return beanNamesIncludingAncestors(lbf).length;
}
/**
* 获取包含祖先在内的所有bean名称数组
* Return all bean names in the factory, including ancestor factories.
* @param lbf the bean factory
* @return the array of matching bean names, or an empty array if none
* @see #beanNamesForTypeIncludingAncestors
*/
public static String[] beanNamesIncludingAncestors(ListableBeanFactory lbf) {
return beanNamesForTypeIncludingAncestors(lbf, Object.class);
}
/**
* 获取包含祖先在内的特定类型的bean名称数组
* Get all bean names for the given type, including those defined in ancestor
* factories. Will return unique names in case of overridden bean definitions.
* <p>Does consider objects created by FactoryBeans, which means that FactoryBeans
* will get initialized. If the object created by the FactoryBean doesn't match,
* the raw FactoryBean itself will be matched against the type.
* <p>This version of {@code beanNamesForTypeIncludingAncestors} automatically
* includes prototypes and FactoryBeans.
* @param lbf the bean factory
* @param type the type that beans must match (as a {@code ResolvableType})
* @return the array of matching bean names, or an empty array if none
* @since 4.2
* @see ListableBeanFactory#getBeanNamesForType(ResolvableType)
*/
public static String[] beanNamesForTypeIncludingAncestors(ListableBeanFactory lbf, ResolvableType type) {
Assert.notNull(lbf, "ListableBeanFactory must not be null");
String[] result = lbf.getBeanNamesForType(type);
// 通过`HierarchicalBeanFactory`类型的工厂继承关系，
// 从而达到bean名称统计的目的
if (lbf instanceof HierarchicalBeanFactory) {
HierarchicalBeanFactory hbf = (HierarchicalBeanFactory) lbf;
if (hbf.getParentBeanFactory() instanceof ListableBeanFactory) {
String[] parentResult = beanNamesForTypeIncludingAncestors(
(ListableBeanFactory) hbf.getParentBeanFactory(), type);
result = mergeNamesWithParent(result, parentResult, hbf);
}
}
return result;
}
/**
* 获取包含祖先在内的特定类型的bean名称数组，
* 同时指定是否包含单例，以及是否允许预初始化
* Get all bean names for the given type, including those defined in ancestor
* factories. Will return unique names in case of overridden bean definitions.
* <p>Does consider objects created by FactoryBeans if the "allowEagerInit"
* flag is set, which means that FactoryBeans will get initialized. If the
* object created by the FactoryBean doesn't match, the raw FactoryBean itself
* will be matched against the type. If "allowEagerInit" is not set,
* only raw FactoryBeans will be checked (which doesn't require initialization
* of each FactoryBean).
* @param lbf the bean factory
* @param type the type that beans must match (as a {@code ResolvableType})
* @param includeNonSingletons whether to include prototype or scoped beans too
* or just singletons (also applies to FactoryBeans)
* @param allowEagerInit whether to initialize <i>lazy-init singletons</i> and
* <i>objects created by FactoryBeans</i> (or by factory methods with a
* "factory-bean" reference) for the type check. Note that FactoryBeans need to be
* eagerly initialized to determine their type: So be aware that passing in "true"
* for this flag will initialize FactoryBeans and "factory-bean" references.
* @return the array of matching bean names, or an empty array if none
* @since 5.2
* @see ListableBeanFactory#getBeanNamesForType(ResolvableType, boolean, boolean)
*/
public static String[] beanNamesForTypeIncludingAncestors(
ListableBeanFactory lbf, ResolvableType type, boolean includeNonSingletons, boolean allowEagerInit) {
Assert.notNull(lbf, "ListableBeanFactory must not be null");
String[] result = lbf.getBeanNamesForType(type, includeNonSingletons, allowEagerInit);
if (lbf instanceof HierarchicalBeanFactory) {
HierarchicalBeanFactory hbf = (HierarchicalBeanFactory) lbf;
if (hbf.getParentBeanFactory() instanceof ListableBeanFactory) {
String[] parentResult = beanNamesForTypeIncludingAncestors(
(ListableBeanFactory) hbf.getParentBeanFactory(), type, includeNonSingletons, allowEagerInit);
result = mergeNamesWithParent(result, parentResult, hbf);
}
}
return result;
}
/**
* 获取包含祖先在内的特定类型的bean名称数组。
* 这儿的特定类型指的是Class这种类型
* Get all bean names for the given type, including those defined in ancestor
* factories. Will return unique names in case of overridden bean definitions.
* <p>Does consider objects created by FactoryBeans, which means that FactoryBeans
* will get initialized. If the object created by the FactoryBean doesn't match,
* the raw FactoryBean itself will be matched against the type.
* <p>This version of {@code beanNamesForTypeIncludingAncestors} automatically
* includes prototypes and FactoryBeans.
* @param lbf the bean factory
* @param type the type that beans must match (as a {@code Class})
* @return the array of matching bean names, or an empty array if none
* @see ListableBeanFactory#getBeanNamesForType(Class)
*/
public static String[] beanNamesForTypeIncludingAncestors(ListableBeanFactory lbf, Class<?> type) {
Assert.notNull(lbf, "ListableBeanFactory must not be null");
String[] result = lbf.getBeanNamesForType(type);
if (lbf instanceof HierarchicalBeanFactory) {
HierarchicalBeanFactory hbf = (HierarchicalBeanFactory) lbf;
if (hbf.getParentBeanFactory() instanceof ListableBeanFactory) {
String[] parentResult = beanNamesForTypeIncludingAncestors(
(ListableBeanFactory) hbf.getParentBeanFactory(), type);
result = mergeNamesWithParent(result, parentResult, hbf);
}
}
return result;
}
/**
* 获取包含祖先在内的特定类型的bean名称数组，
* 同时指定是否包含单例，以及是否允许预初始化，
* 这儿的特定类型指的是Class这种类型
* Get all bean names for the given type, including those defined in ancestor
* factories. Will return unique names in case of overridden bean definitions.
* <p>Does consider objects created by FactoryBeans if the "allowEagerInit"
* flag is set, which means that FactoryBeans will get initialized. If the
* object created by the FactoryBean doesn't match, the raw FactoryBean itself
* will be matched against the type. If "allowEagerInit" is not set,
* only raw FactoryBeans will be checked (which doesn't require initialization
* of each FactoryBean).
* @param lbf the bean factory
* @param includeNonSingletons whether to include prototype or scoped beans too
* or just singletons (also applies to FactoryBeans)
* @param allowEagerInit whether to initialize <i>lazy-init singletons</i> and
* <i>objects created by FactoryBeans</i> (or by factory methods with a
* "factory-bean" reference) for the type check. Note that FactoryBeans need to be
* eagerly initialized to determine their type: So be aware that passing in "true"
* for this flag will initialize FactoryBeans and "factory-bean" references.
* @param type the type that beans must match
* @return the array of matching bean names, or an empty array if none
* @see ListableBeanFactory#getBeanNamesForType(Class, boolean, boolean)
*/
public static String[] beanNamesForTypeIncludingAncestors(
ListableBeanFactory lbf, Class<?> type, boolean includeNonSingletons, boolean allowEagerInit) {
Assert.notNull(lbf, "ListableBeanFactory must not be null");
String[] result = lbf.getBeanNamesForType(type, includeNonSingletons, allowEagerInit);
if (lbf instanceof HierarchicalBeanFactory) {
HierarchicalBeanFactory hbf = (HierarchicalBeanFactory) lbf;
if (hbf.getParentBeanFactory() instanceof ListableBeanFactory) {
String[] parentResult = beanNamesForTypeIncludingAncestors(
(ListableBeanFactory) hbf.getParentBeanFactory(), type, includeNonSingletons, allowEagerInit);
result = mergeNamesWithParent(result, parentResult, hbf);
}
}
return result;
}
/**
* 获取包含祖先在内的特定类型（且使用了特定注解）的bean名称数组
* Get all bean names whose {@code Class} has the supplied {@link Annotation}
* type, including those defined in ancestor factories, without creating any bean
* instances yet. Will return unique names in case of overridden bean definitions.
* @param lbf the bean factory
* @param annotationType the type of annotation to look for
* @return the array of matching bean names, or an empty array if none
* @since 5.0
* @see ListableBeanFactory#getBeanNamesForAnnotation(Class)
*/
public static String[] beanNamesForAnnotationIncludingAncestors(
ListableBeanFactory lbf, Class<? extends Annotation> annotationType) {
Assert.notNull(lbf, "ListableBeanFactory must not be null");
String[] result = lbf.getBeanNamesForAnnotation(annotationType);
if (lbf instanceof HierarchicalBeanFactory) {
HierarchicalBeanFactory hbf = (HierarchicalBeanFactory) lbf;
if (hbf.getParentBeanFactory() instanceof ListableBeanFactory) {
String[] parentResult = beanNamesForAnnotationIncludingAncestors(
(ListableBeanFactory) hbf.getParentBeanFactory(), annotationType);
result = mergeNamesWithParent(result, parentResult, hbf);
}
}
return result;
}
// Retrieval of bean instances
/**
* 获取包含祖先在内的特定类型的bean实例map（key为bean名称，value为bean实例）
* Return all beans of the given type or subtypes, also picking up beans defined in
* ancestor bean factories if the current bean factory is a HierarchicalBeanFactory.
* The returned Map will only contain beans of this type.
* <p>Does consider objects created by FactoryBeans, which means that FactoryBeans
* will get initialized. If the object created by the FactoryBean doesn't match,
* the raw FactoryBean itself will be matched against the type.
* <p><b>Note: Beans of the same name will take precedence at the 'lowest' factory level,
* i.e. such beans will be returned from the lowest factory that they are being found in,
* hiding corresponding beans in ancestor factories.</b> This feature allows for
* 'replacing' beans by explicitly choosing the same bean name in a child factory;
* the bean in the ancestor factory won't be visible then, not even for by-type lookups.
* @param lbf the bean factory
* @param type type of bean to match
* @return the Map of matching bean instances, or an empty Map if none
* @throws BeansException if a bean could not be created
* @see ListableBeanFactory#getBeansOfType(Class)
*/
public static <T> Map<String, T> beansOfTypeIncludingAncestors(ListableBeanFactory lbf, Class<T> type)
throws BeansException {
Assert.notNull(lbf, "ListableBeanFactory must not be null");
Map<String, T> result = new LinkedHashMap<>(4);
result.putAll(lbf.getBeansOfType(type));
if (lbf instanceof HierarchicalBeanFactory) {
HierarchicalBeanFactory hbf = (HierarchicalBeanFactory) lbf;
if (hbf.getParentBeanFactory() instanceof ListableBeanFactory) {
Map<String, T> parentResult = beansOfTypeIncludingAncestors(
(ListableBeanFactory) hbf.getParentBeanFactory(), type);
parentResult.forEach((beanName, beanInstance) -> {
if (!result.containsKey(beanName) && !hbf.containsLocalBean(beanName)) {
result.put(beanName, beanInstance);
}
});
}
}
return result;
}
/**
* 获取包含祖先在内的特定类型的bean实例map（key为bean名称，value为bean实例）
* 同时指定是否包含单例，以及是否允许预初始化，
* Return all beans of the given type or subtypes, also picking up beans defined in
* ancestor bean factories if the current bean factory is a HierarchicalBeanFactory.
* The returned Map will only contain beans of this type.
* <p>Does consider objects created by FactoryBeans if the "allowEagerInit" flag is set,
* which means that FactoryBeans will get initialized. If the object created by the
* FactoryBean doesn't match, the raw FactoryBean itself will be matched against the
* type. If "allowEagerInit" is not set, only raw FactoryBeans will be checked
* (which doesn't require initialization of each FactoryBean).
* <p><b>Note: Beans of the same name will take precedence at the 'lowest' factory level,
* i.e. such beans will be returned from the lowest factory that they are being found in,
* hiding corresponding beans in ancestor factories.</b> This feature allows for
* 'replacing' beans by explicitly choosing the same bean name in a child factory;
* the bean in the ancestor factory won't be visible then, not even for by-type lookups.
* @param lbf the bean factory
* @param type type of bean to match
* @param includeNonSingletons whether to include prototype or scoped beans too
* or just singletons (also applies to FactoryBeans)
* @param allowEagerInit whether to initialize <i>lazy-init singletons</i> and
* <i>objects created by FactoryBeans</i> (or by factory methods with a
* "factory-bean" reference) for the type check. Note that FactoryBeans need to be
* eagerly initialized to determine their type: So be aware that passing in "true"
* for this flag will initialize FactoryBeans and "factory-bean" references.
* @return the Map of matching bean instances, or an empty Map if none
* @throws BeansException if a bean could not be created
* @see ListableBeanFactory#getBeansOfType(Class, boolean, boolean)
*/
public static <T> Map<String, T> beansOfTypeIncludingAncestors(
ListableBeanFactory lbf, Class<T> type, boolean includeNonSingletons, boolean allowEagerInit)
throws BeansException {
Assert.notNull(lbf, "ListableBeanFactory must not be null");
Map<String, T> result = new LinkedHashMap<>(4);
result.putAll(lbf.getBeansOfType(type, includeNonSingletons, allowEagerInit));
if (lbf instanceof HierarchicalBeanFactory) {
HierarchicalBeanFactory hbf = (HierarchicalBeanFactory) lbf;
if (hbf.getParentBeanFactory() instanceof ListableBeanFactory) {
Map<String, T> parentResult = beansOfTypeIncludingAncestors(
(ListableBeanFactory) hbf.getParentBeanFactory(), type, includeNonSingletons, allowEagerInit);
parentResult.forEach((beanName, beanInstance) -> {
if (!result.containsKey(beanName) && !hbf.containsLocalBean(beanName)) {
result.put(beanName, beanInstance);
}
});
}
}
return result;
}
/**
* 获取包含祖先在内的特定类型的bean实例，这儿通过`uniqueBean`方法校验唯一性
* Return a single bean of the given type or subtypes, also picking up beans
* defined in ancestor bean factories if the current bean factory is a
* HierarchicalBeanFactory. Useful convenience method when we expect a
* single bean and don't care about the bean name.
* <p>Does consider objects created by FactoryBeans, which means that FactoryBeans
* will get initialized. If the object created by the FactoryBean doesn't match,
* the raw FactoryBean itself will be matched against the type.
* <p>This version of {@code beanOfTypeIncludingAncestors} automatically includes
* prototypes and FactoryBeans.
* <p><b>Note: Beans of the same name will take precedence at the 'lowest' factory level,
* i.e. such beans will be returned from the lowest factory that they are being found in,
* hiding corresponding beans in ancestor factories.</b> This feature allows for
* 'replacing' beans by explicitly choosing the same bean name in a child factory;
* the bean in the ancestor factory won't be visible then, not even for by-type lookups.
* @param lbf the bean factory
* @param type type of bean to match
* @return the matching bean instance
* @throws NoSuchBeanDefinitionException if no bean of the given type was found
* @throws NoUniqueBeanDefinitionException if more than one bean of the given type was found
* @throws BeansException if the bean could not be created
* @see #beansOfTypeIncludingAncestors(ListableBeanFactory, Class)
*/
public static <T> T beanOfTypeIncludingAncestors(ListableBeanFactory lbf, Class<T> type)
throws BeansException {
Map<String, T> beansOfType = beansOfTypeIncludingAncestors(lbf, type);
return uniqueBean(type, beansOfType);
}
/**
* 获取包含祖先在内的特定类型的bean实例，这儿通过`uniqueBean`方法校验唯一性
* 同时指定是否包含单例，以及是否允许预初始化，
* Return a single bean of the given type or subtypes, also picking up beans
* defined in ancestor bean factories if the current bean factory is a
* HierarchicalBeanFactory. Useful convenience method when we expect a
* single bean and don't care about the bean name.
* <p>Does consider objects created by FactoryBeans if the "allowEagerInit" flag is set,
* which means that FactoryBeans will get initialized. If the object created by the
* FactoryBean doesn't match, the raw FactoryBean itself will be matched against the
* type. If "allowEagerInit" is not set, only raw FactoryBeans will be checked
* (which doesn't require initialization of each FactoryBean).
* <p><b>Note: Beans of the same name will take precedence at the 'lowest' factory level,
* i.e. such beans will be returned from the lowest factory that they are being found in,
* hiding corresponding beans in ancestor factories.</b> This feature allows for
* 'replacing' beans by explicitly choosing the same bean name in a child factory;
* the bean in the ancestor factory won't be visible then, not even for by-type lookups.
* @param lbf the bean factory
* @param type type of bean to match
* @param includeNonSingletons whether to include prototype or scoped beans too
* or just singletons (also applies to FactoryBeans)
* @param allowEagerInit whether to initialize <i>lazy-init singletons</i> and
* <i>objects created by FactoryBeans</i> (or by factory methods with a
* "factory-bean" reference) for the type check. Note that FactoryBeans need to be
* eagerly initialized to determine their type: So be aware that passing in "true"
* for this flag will initialize FactoryBeans and "factory-bean" references.
* @return the matching bean instance
* @throws NoSuchBeanDefinitionException if no bean of the given type was found
* @throws NoUniqueBeanDefinitionException if more than one bean of the given type was found
* @throws BeansException if the bean could not be created
* @see #beansOfTypeIncludingAncestors(ListableBeanFactory, Class, boolean, boolean)
*/
public static <T> T beanOfTypeIncludingAncestors(
ListableBeanFactory lbf, Class<T> type, boolean includeNonSingletons, boolean allowEagerInit)
throws BeansException {
Map<String, T> beansOfType = beansOfTypeIncludingAncestors(lbf, type, includeNonSingletons, allowEagerInit);
return uniqueBean(type, beansOfType);
}
/**
* 获取包含祖先在内的特定类型的bean实例，这儿通过`uniqueBean`方法校验唯一性
* Return a single bean of the given type or subtypes, not looking in ancestor
* factories. Useful convenience method when we expect a single bean and
* don't care about the bean name.
* <p>Does consider objects created by FactoryBeans, which means that FactoryBeans
* will get initialized. If the object created by the FactoryBean doesn't match,
* the raw FactoryBean itself will be matched against the type.
* <p>This version of {@code beanOfType} automatically includes
* prototypes and FactoryBeans.
* @param lbf the bean factory
* @param type type of bean to match
* @return the matching bean instance
* @throws NoSuchBeanDefinitionException if no bean of the given type was found
* @throws NoUniqueBeanDefinitionException if more than one bean of the given type was found
* @throws BeansException if the bean could not be created
* @see ListableBeanFactory#getBeansOfType(Class)
*/
public static <T> T beanOfType(ListableBeanFactory lbf, Class<T> type) throws BeansException {
Assert.notNull(lbf, "ListableBeanFactory must not be null");
Map<String, T> beansOfType = lbf.getBeansOfType(type);
return uniqueBean(type, beansOfType);
}
/**
* 获取特定类型的bean实例，这儿通过`uniqueBean`方法校验唯一性
* 同时指定是否包含单例，以及是否允许预初始化，
* Return a single bean of the given type or subtypes, not looking in ancestor
* factories. Useful convenience method when we expect a single bean and
* don't care about the bean name.
* <p>Does consider objects created by FactoryBeans if the "allowEagerInit"
* flag is set, which means that FactoryBeans will get initialized. If the
* object created by the FactoryBean doesn't match, the raw FactoryBean itself
* will be matched against the type. If "allowEagerInit" is not set,
* only raw FactoryBeans will be checked (which doesn't require initialization
* of each FactoryBean).
* @param lbf the bean factory
* @param type type of bean to match
* @param includeNonSingletons whether to include prototype or scoped beans too
* or just singletons (also applies to FactoryBeans)
* @param allowEagerInit whether to initialize <i>lazy-init singletons</i> and
* <i>objects created by FactoryBeans</i> (or by factory methods with a
* "factory-bean" reference) for the type check. Note that FactoryBeans need to be
* eagerly initialized to determine their type: So be aware that passing in "true"
* for this flag will initialize FactoryBeans and "factory-bean" references.
* @return the matching bean instance
* @throws NoSuchBeanDefinitionException if no bean of the given type was found
* @throws NoUniqueBeanDefinitionException if more than one bean of the given type was found
* @throws BeansException if the bean could not be created
* @see ListableBeanFactory#getBeansOfType(Class, boolean, boolean)
*/
public static <T> T beanOfType(
ListableBeanFactory lbf, Class<T> type, boolean includeNonSingletons, boolean allowEagerInit)
throws BeansException {
Assert.notNull(lbf, "ListableBeanFactory must not be null");
Map<String, T> beansOfType = lbf.getBeansOfType(type, includeNonSingletons, allowEagerInit);
return uniqueBean(type, beansOfType);
}
/**
* 合并bean名称，内部通过List的addAll方法实现
* Merge the given bean names result with the given parent result.
* @param result the local bean name result
* @param parentResult the parent bean name result (possibly empty)
* @param hbf the local bean factory
* @return the merged result (possibly the local result as-is)
* @since 4.3.15
*/
private static String[] mergeNamesWithParent(String[] result, String[] parentResult, HierarchicalBeanFactory hbf) {
if (parentResult.length == 0) {
return result;
}
List<String> merged = new ArrayList<>(result.length + parentResult.length);
merged.addAll(Arrays.asList(result));
for (String beanName : parentResult) {
if (!merged.contains(beanName) && !hbf.containsLocalBean(beanName)) {
merged.add(beanName);
}
}
return StringUtils.toStringArray(merged);
}
/**
* 校验map的唯一性
* Extract a unique bean for the given type from the given Map of matching beans.
* @param type type of bean to match
* @param matchingBeans all matching beans found
* @return the unique bean instance
* @throws NoSuchBeanDefinitionException if no bean of the given type was found
* @throws NoUniqueBeanDefinitionException if more than one bean of the given type was found
*/
private static <T> T uniqueBean(Class<T> type, Map<String, T> matchingBeans) {
int count = matchingBeans.size();
if (count == 1) {
return matchingBeans.values().iterator().next();
}
else if (count > 1) {
throw new NoUniqueBeanDefinitionException(type, matchingBeans.keySet());
}
else {
throw new NoSuchBeanDefinitionException(type);
}
}
}
总结
通过上面我们对源码的分析，我们大致看出此工具类包含以下几类方法：
- isFactoryDereference -- 根据名称判断是否是一个工厂bean的名称
- transformedBeanName -- 将带有&的所有前缀全部去掉
- isGeneratedBeanName -- 判断是否内部生成的bean名称
- originalBeanName -- 获取内部bean所在的外部bean
- countBeansIncludingAncestors -- 获取包含祖先在内的所有bean的数量
- beanNamesForTypeIncludingAncestors -- 获取包含祖先在内的bean名称数组，存在多个重载方法
- beansOfTypeIncludingAncestors -- 获取包含祖先在内的bean实例map，存在多个重载方法
- beanOfTypeIncludingAncestors -- 获取包含祖先在内的bean实例，存在多个重载方法
- beanOfType -- 获取特定类型的bean实例（不包含祖先）
所有这些方法，基本都是对bean名称、bean实例、bean类型的判断和处理，是构成spring ioc的核心工具类方法。
