Spring源码-finishBeanFactoryInitialization方法
protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {
// Initialize conversion service for this context.
if (beanFactory.containsBean(CONVERSION_SERVICE_BEAN_NAME) &&
beanFactory.isTypeMatch(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class)) {
beanFactory.setConversionService(
beanFactory.getBean(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class));
}
// Register a default embedded value resolver if no BeanFactoryPostProcessor
// (such as a PropertySourcesPlaceholderConfigurer bean) registered any before:
// at this point, primarily for resolution in annotation attribute values.
if (!beanFactory.hasEmbeddedValueResolver()) {
beanFactory.addEmbeddedValueResolver(strVal -> getEnvironment().resolvePlaceholders(strVal));
}
// Initialize LoadTimeWeaverAware beans early to allow for registering their transformers early.
String[] weaverAwareNames = beanFactory.getBeanNamesForType(LoadTimeWeaverAware.class, false, false);
for (String weaverAwareName : weaverAwareNames) {
getBean(weaverAwareName);
}
// Stop using the temporary ClassLoader for type matching.
beanFactory.setTempClassLoader(null);
// Allow for caching all bean definition metadata, not expecting further changes.
beanFactory.freezeConfiguration();
// Instantiate all remaining (non-lazy-init) singletons.
beanFactory.preInstantiateSingletons();
}
finishBeanFactoryInitialization方法设置ConversionService类型转换服务，还设置了EmbeddedValueResolver值处理器，用于解析value中存在的${}。初始化LoadTimeWeaverAware。冻结BeanDifinition信息。初始化非lazy的bean。
ConversionService接口的默认实现是DefaultConversionService，ConversionService里面主要保存了很多converter，由converter进行类型转换。
public static void addDefaultConverters(ConverterRegistry converterRegistry) {
addScalarConverters(converterRegistry);
addCollectionConverters(converterRegistry);
converterRegistry.addConverter(new ByteBufferConverter((ConversionService) converterRegistry));
converterRegistry.addConverter(new StringToTimeZoneConverter());
converterRegistry.addConverter(new ZoneIdToTimeZoneConverter());
converterRegistry.addConverter(new ZonedDateTimeToCalendarConverter());
converterRegistry.addConverter(new ObjectToObjectConverter());
converterRegistry.addConverter(new IdToEntityConverter((ConversionService) converterRegistry));
converterRegistry.addConverter(new FallbackObjectToStringConverter());
converterRegistry.addConverter(new ObjectToOptionalConverter((ConversionService) converterRegistry));
}
public static void addCollectionConverters(ConverterRegistry converterRegistry) {
ConversionService conversionService = (ConversionService) converterRegistry;
converterRegistry.addConverter(new ArrayToCollectionConverter(conversionService));
converterRegistry.addConverter(new CollectionToArrayConverter(conversionService));
converterRegistry.addConverter(new ArrayToArrayConverter(conversionService));
converterRegistry.addConverter(new CollectionToCollectionConverter(conversionService));
converterRegistry.addConverter(new MapToMapConverter(conversionService));
converterRegistry.addConverter(new ArrayToStringConverter(conversionService));
converterRegistry.addConverter(new StringToArrayConverter(conversionService));
converterRegistry.addConverter(new ArrayToObjectConverter(conversionService));
converterRegistry.addConverter(new ObjectToArrayConverter(conversionService));
converterRegistry.addConverter(new CollectionToStringConverter(conversionService));
converterRegistry.addConverter(new StringToCollectionConverter(conversionService));
converterRegistry.addConverter(new CollectionToObjectConverter(conversionService));
converterRegistry.addConverter(new ObjectToCollectionConverter(conversionService));
converterRegistry.addConverter(new StreamConverter(conversionService));
}
private static void addScalarConverters(ConverterRegistry converterRegistry) {
converterRegistry.addConverterFactory(new NumberToNumberConverterFactory());
converterRegistry.addConverterFactory(new StringToNumberConverterFactory());
converterRegistry.addConverter(Number.class, String.class, new ObjectToStringConverter());
converterRegistry.addConverter(new StringToCharacterConverter());
converterRegistry.addConverter(Character.class, String.class, new ObjectToStringConverter());
converterRegistry.addConverter(new NumberToCharacterConverter());
converterRegistry.addConverterFactory(new CharacterToNumberFactory());
converterRegistry.addConverter(new StringToBooleanConverter());
converterRegistry.addConverter(Boolean.class, String.class, new ObjectToStringConverter());
converterRegistry.addConverterFactory(new StringToEnumConverterFactory());
converterRegistry.addConverter(new EnumToStringConverter((ConversionService) converterRegistry));
converterRegistry.addConverterFactory(new IntegerToEnumConverterFactory());
converterRegistry.addConverter(new EnumToIntegerConverter((ConversionService) converterRegistry));
converterRegistry.addConverter(new StringToLocaleConverter());
converterRegistry.addConverter(Locale.class, String.class, new ObjectToStringConverter());
converterRegistry.addConverter(new StringToCharsetConverter());
converterRegistry.addConverter(Charset.class, String.class, new ObjectToStringConverter());
converterRegistry.addConverter(new StringToCurrencyConverter());
converterRegistry.addConverter(Currency.class, String.class, new ObjectToStringConverter());
converterRegistry.addConverter(new StringToPropertiesConverter());
converterRegistry.addConverter(new PropertiesToStringConverter());
converterRegistry.addConverter(new StringToUUIDConverter());
converterRegistry.addConverter(UUID.class, String.class, new ObjectToStringConverter());
}
converter有三类实现，分别是Converter<S, T>，GenericConverter，ConverterFactory<S, R>。
@FunctionalInterface
public interface Converter<S, T> {
/**
* Convert the source object of type {@code S} to target type {@code T}.
* @param source the source object to convert, which must be an instance of {@code S} (never {@code null})
* @return the converted object, which must be an instance of {@code T} (potentially {@code null})
* @throws IllegalArgumentException if the source cannot be converted to the desired target type
*/
@Nullable
T convert(S source);
/**
* Construct a composed {@link Converter} that first applies this {@link Converter}
* to its input, and then applies the {@code after} {@link Converter} to the
* result.
* @param after the {@link Converter} to apply after this {@link Converter}
* is applied
* @param <U> the type of output of both the {@code after} {@link Converter}
* and the composed {@link Converter}
* @return a composed {@link Converter} that first applies this {@link Converter}
* and then applies the {@code after} {@link Converter}
* @since 5.3
*/
default <U> Converter<S, U> andThen(Converter<? super T, ? extends U> after) {
Assert.notNull(after, "After Converter must not be null");
return (S s) -> {
T initialResult = convert(s);
return (initialResult != null ? after.convert(initialResult) : null);
};
}
}
Converter<S, T>由类型S转换成类型T。提供了一对一的转换服务。比如
class StringToTimeZoneConverter implements Converter<String, TimeZone> {
@Override
public TimeZone convert(String source) {
return StringUtils.parseTimeZoneString(source);
}
}
GenericConverter提供了两种或多种类型之间的转换。
public interface GenericConverter {
/**
* Return the source and target types that this converter can convert between.
* <p>Each entry is a convertible source-to-target type pair.
* <p>For {@link ConditionalConverter conditional converters} this method may return
* {@code null} to indicate all source-to-target pairs should be considered.
*/
@Nullable
Set<ConvertiblePair> getConvertibleTypes();
/**
* Convert the source object to the targetType described by the {@code TypeDescriptor}.
* @param source the source object to convert (may be {@code null})
* @param sourceType the type descriptor of the field we are converting from
* @param targetType the type descriptor of the field we are converting to
* @return the converted object
*/
@Nullable
Object convert(@Nullable Object source, TypeDescriptor sourceType, TypeDescriptor targetType);
/**
* Holder for a source-to-target class pair.
*/
final class ConvertiblePair {
private final Class<?> sourceType;
private final Class<?> targetType;
/**
* Create a new source-to-target pair.
* @param sourceType the source type
* @param targetType the target type
*/
public ConvertiblePair(Class<?> sourceType, Class<?> targetType) {
Assert.notNull(sourceType, "Source type must not be null");
Assert.notNull(targetType, "Target type must not be null");
this.sourceType = sourceType;
this.targetType = targetType;
}
public Class<?> getSourceType() {
return this.sourceType;
}
public Class<?> getTargetType() {
return this.targetType;
}
@Override
public boolean equals(@Nullable Object other) {
if (this == other) {
return true;
}
if (other == null || other.getClass() != ConvertiblePair.class) {
return false;
}
ConvertiblePair otherPair = (ConvertiblePair) other;
return (this.sourceType == otherPair.sourceType && this.targetType == otherPair.targetType);
}
@Override
public int hashCode() {
return (this.sourceType.hashCode() * 31 + this.targetType.hashCode());
}
@Override
public String toString() {
return (this.sourceType.getName() + " -> " + this.targetType.getName());
}
}
}
比如：
final class ArrayToCollectionConverter implements ConditionalGenericConverter {
private final ConversionService conversionService;
public ArrayToCollectionConverter(ConversionService conversionService) {
this.conversionService = conversionService;
}
@Override
public Set<ConvertiblePair> getConvertibleTypes() {
return Collections.singleton(new ConvertiblePair(Object[].class, Collection.class));
}
@Override
public boolean matches(TypeDescriptor sourceType, TypeDescriptor targetType) {
return ConversionUtils.canConvertElements(
sourceType.getElementTypeDescriptor(), targetType.getElementTypeDescriptor(), this.conversionService);
}
@Override
@Nullable
public Object convert(@Nullable Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
if (source == null) {
return null;
}
int length = Array.getLength(source);
TypeDescriptor elementDesc = targetType.getElementTypeDescriptor();
Collection<Object> target = CollectionFactory.createCollection(targetType.getType(),
(elementDesc != null ? elementDesc.getType() : null), length);
if (elementDesc == null) {
for (int i = 0; i < length; i++) {
Object sourceElement = Array.get(source, i);
target.add(sourceElement);
}
}
else {
for (int i = 0; i < length; i++) {
Object sourceElement = Array.get(source, i);
Object targetElement = this.conversionService.convert(sourceElement,
sourceType.elementTypeDescriptor(sourceElement), elementDesc);
target.add(targetElement);
}
}
return target;
}
}
ConverterFactory<S, R>提供了从类型S到类型T的转换，类型T是R的子类或R。提供了从一种类型转换多种类型的服务。
final class StringToNumberConverterFactory implements ConverterFactory<String, Number> {
@Override
public <T extends Number> Converter<String, T> getConverter(Class<T> targetType) {
return new StringToNumber<>(targetType);
}
private static final class StringToNumber<T extends Number> implements Converter<String, T> {
private final Class<T> targetType;
public StringToNumber(Class<T> targetType) {
this.targetType = targetType;
}
@Override
@Nullable
public T convert(String source) {
if (source.isEmpty()) {
return null;
}
return NumberUtils.parseNumber(source, this.targetType);
}
}
}
EmbeddedValueResolver是怎么加到beanFactory中的，是通过BeanFactoryPostProcessor加入的，比如PropertySourcesPlaceholderConfigurer。
@Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
if (this.propertySources == null) {
this.propertySources = new MutablePropertySources();
if (this.environment != null) {
this.propertySources.addLast(
new PropertySource<Environment>(ENVIRONMENT_PROPERTIES_PROPERTY_SOURCE_NAME, this.environment) {
@Override
@Nullable
public String getProperty(String key) {
return this.source.getProperty(key);
}
}
);
}
try {
PropertySource<?> localPropertySource =
new PropertiesPropertySource(LOCAL_PROPERTIES_PROPERTY_SOURCE_NAME, mergeProperties());
if (this.localOverride) {
this.propertySources.addFirst(localPropertySource);
}
else {
this.propertySources.addLast(localPropertySource);
}
}
catch (IOException ex) {
throw new BeanInitializationException("Could not load properties", ex);
}
}
processProperties(beanFactory, new PropertySourcesPropertyResolver(this.propertySources));
this.appliedPropertySources = this.propertySources;
}
protected void processProperties(ConfigurableListableBeanFactory beanFactoryToProcess,
final ConfigurablePropertyResolver propertyResolver) throws BeansException {
propertyResolver.setPlaceholderPrefix(this.placeholderPrefix);
propertyResolver.setPlaceholderSuffix(this.placeholderSuffix);
propertyResolver.setValueSeparator(this.valueSeparator);
StringValueResolver valueResolver = strVal -> {
String resolved = (this.ignoreUnresolvablePlaceholders ?
propertyResolver.resolvePlaceholders(strVal) :
propertyResolver.resolveRequiredPlaceholders(strVal));
if (this.trimValues) {
resolved = resolved.trim();
}
return (resolved.equals(this.nullValue) ? null : resolved);
};
doProcessProperties(beanFactoryToProcess, valueResolver);
}
protected void doProcessProperties(ConfigurableListableBeanFactory beanFactoryToProcess,
StringValueResolver valueResolver) {
BeanDefinitionVisitor visitor = new BeanDefinitionVisitor(valueResolver);
String[] beanNames = beanFactoryToProcess.getBeanDefinitionNames();
for (String curName : beanNames) {
// Check that we're not parsing our own bean definition,
// to avoid failing on unresolvable placeholders in properties file locations.
if (!(curName.equals(this.beanName) && beanFactoryToProcess.equals(this.beanFactory))) {
BeanDefinition bd = beanFactoryToProcess.getBeanDefinition(curName);
try {
visitor.visitBeanDefinition(bd);
}
catch (Exception ex) {
throw new BeanDefinitionStoreException(bd.getResourceDescription(), curName, ex.getMessage(), ex);
}
}
}
// New in Spring 2.5: resolve placeholders in alias target names and aliases as well.
beanFactoryToProcess.resolveAliases(valueResolver);
// New in Spring 3.0: resolve placeholders in embedded values such as annotation attributes.
beanFactoryToProcess.addEmbeddedValueResolver(valueResolver);
}
例子：
DateConversionService
public class DateConversionService implements Converter<String, Date> {
@Override
public Date convert(String source) {
if (source != null) {
SimpleDateFormat format = new SimpleDateFormat("YYYY-MM-DD");
try {
return format.parse(source);
} catch (ParseException e) {
e.printStackTrace();
}
}
return null;
}
}
自定义转换器将字符串转成日期。
public class Person {
private String name;
private Date birthday;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
@Override
public String toString() {
return "Person{" +
"name='" + name + '\'' +
", birthday=" + birthday +
'}';
}
}
conversionService.xml
<bean id="person" class="conversionService.Person">
<property name="name" value="张三"/>
<property name="birthday" value="2022-01-01"/>
</bean>
<bean id="dateConversionService" class="conversionService.DateConversionService"></bean>
<bean id="conversionService"
class="org.springframework.context.support.ConversionServiceFactoryBean">
<property name="converters">
<set>
<ref bean="dateConversionService"/>
</set>
</property>
</bean>
测试：
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("conversionService.xml");
Person bean = context.getBean(Person.class);
System.out.println(bean);
