处理器修改合并bean定义
前面实例化完成了，之后要进行处理器的处理，也就是MergedBeanDefinitionPostProcessor处理器的处理：
protected void applyMergedBeanDefinitionPostProcessors(RootBeanDefinition mbd, Class<?> beanType, String beanName) {
for (BeanPostProcessor bp : getBeanPostProcessors()) {
if (bp instanceof MergedBeanDefinitionPostProcessor) {
MergedBeanDefinitionPostProcessor bdp = (MergedBeanDefinitionPostProcessor) bp;
bdp.postProcessMergedBeanDefinition(mbd, beanType, beanName);
}
}
}
CommonAnnotationBeanPostProcessor的postProcessMergedBeanDefinition处理
@Override
public void postProcessMergedBeanDefinition(RootBeanDefinition beanDefinition, Class<?> beanType, String beanName) {
super.postProcessMergedBeanDefinition(beanDefinition, beanType, beanName);
InjectionMetadata metadata = findResourceMetadata(beanName, beanType, null);
metadata.checkConfigMembers(beanDefinition);
}
InitDestroyAnnotationBeanPostProcessor的处理
这个主要是生命周期的一些回调函数的注册，比如PostConstruct和PreDestroy注解的方法。
@Override
public void postProcessMergedBeanDefinition(RootBeanDefinition beanDefinition, Class<?> beanType, String beanName) {
LifecycleMetadata metadata = findLifecycleMetadata(beanType);//找到生命周期方法
metadata.checkConfigMembers(beanDefinition);//注册初始化和销毁的回调方法
}
findLifecycleMetadata寻找生命周期元数据
private LifecycleMetadata findLifecycleMetadata(Class<?> clazz) {
if (this.lifecycleMetadataCache == null) {
// Happens after deserialization, during destruction...
return buildLifecycleMetadata(clazz);
}
// Quick check on the concurrent map first, with minimal locking.//双重检测，尽可能少的用锁
LifecycleMetadata metadata = this.lifecycleMetadataCache.get(clazz);
if (metadata == null) {
synchronized (this.lifecycleMetadataCache) {
metadata = this.lifecycleMetadataCache.get(clazz);
if (metadata == null) {
metadata = buildLifecycleMetadata(clazz);
this.lifecycleMetadataCache.put(clazz, metadata);//放入缓存
}
return metadata;
}
}
return metadata;
}
buildLifecycleMetadata构建生命周期元数据
一般来说都是要经过这步的，因为都需要经过注册，除非是第二次来，有缓存了。
其实就是检测clazz以及父类的所有的方法，看是不是有PostConstruct和PreDestroy注解，有的话就把方法封装成LifecycleElement加入对应的集合：
private LifecycleMetadata buildLifecycleMetadata(final Class<?> clazz) {
if (!AnnotationUtils.isCandidateClass(clazz, Arrays.asList(this.initAnnotationType, this.destroyAnnotationType))) {
return this.emptyLifecycleMetadata;
}
List<LifecycleElement> initMethods = new ArrayList<>();
List<LifecycleElement> destroyMethods = new ArrayList<>();
Class<?> targetClass = clazz;
do {
final List<LifecycleElement> currInitMethods = new ArrayList<>();
final List<LifecycleElement> currDestroyMethods = new ArrayList<>();
//如果有PostConstruct和PreDestroy注解的方法就添加到currInitMethods和currDestroyMethods里，包括父类，因为可能CGLIB动态代理
ReflectionUtils.doWithLocalMethods(targetClass, method -> {
if (this.initAnnotationType != null && method.isAnnotationPresent(this.initAnnotationType)) {
LifecycleElement element = new LifecycleElement(method);
currInitMethods.add(element);
if (logger.isTraceEnabled()) {
logger.trace("Found init method on class [" + clazz.getName() + "]: " + method);
}
}
if (this.destroyAnnotationType != null && method.isAnnotationPresent(this.destroyAnnotationType)) {
currDestroyMethods.add(new LifecycleElement(method));
if (logger.isTraceEnabled()) {
logger.trace("Found destroy method on class [" + clazz.getName() + "]: " + method);
}
}
});
//加入相应的声明周期方法里
initMethods.addAll(0, currInitMethods);
destroyMethods.addAll(currDestroyMethods);
targetClass = targetClass.getSuperclass();
}
while (targetClass != null && targetClass != Object.class);
//有一个不为空就封装一个LifecycleMetadata返回，否则就返回空的emptyLifecycleMetadata
return (initMethods.isEmpty() && destroyMethods.isEmpty() ? this.emptyLifecycleMetadata :
new LifecycleMetadata(clazz, initMethods, destroyMethods));
}
emptyLifecycleMetadata都是空方法
如果没有注解的话会返回一个空的emptyLifecycleMetadata 。
private final transient LifecycleMetadata emptyLifecycleMetadata =
new LifecycleMetadata(Object.class, Collections.emptyList(), Collections.emptyList()) {
@Override
public void checkConfigMembers(RootBeanDefinition beanDefinition) {
}
@Override
public void invokeInitMethods(Object target, String beanName) {
}
@Override
public void invokeDestroyMethods(Object target, String beanName) {
}
@Override
public boolean hasDestroyMethods() {
return false;
}
};
LifecycleMetadata的checkConfigMembers
会将初始化和销毁的回调方法注册到beanDefinition中，并且标记已经检查过的方法，放入checkedInitMethods 和checkedDestroyMethods 方法集合。
public void checkConfigMembers(RootBeanDefinition beanDefinition) {
Set<LifecycleElement> checkedInitMethods = new LinkedHashSet<>(this.initMethods.size());
for (LifecycleElement element : this.initMethods) {
String methodIdentifier = element.getIdentifier();
if (!beanDefinition.isExternallyManagedInitMethod(methodIdentifier)) {
beanDefinition.registerExternallyManagedInitMethod(methodIdentifier);//注册初始化调用方法
checkedInitMethods.add(element);
if (logger.isTraceEnabled()) {
logger.trace("Registered init method on class [" + this.targetClass.getName() + "]: " + element);
}
}
}
Set<LifecycleElement> checkedDestroyMethods = new LinkedHashSet<>(this.destroyMethods.size());
for (LifecycleElement element : this.destroyMethods) {
String methodIdentifier = element.getIdentifier();
if (!beanDefinition.isExternallyManagedDestroyMethod(methodIdentifier)) {
beanDefinition.registerExternallyManagedDestroyMethod(methodIdentifier);//注册销毁调用方法
checkedDestroyMethods.add(element);
if (logger.isTraceEnabled()) {
logger.trace("Registered destroy method on class [" + this.targetClass.getName() + "]: " + element);
}
}
}
this.checkedInitMethods = checkedInitMethods;
this.checkedDestroyMethods = checkedDestroyMethods;
}
findResourceMetadata的处理
跟上面一样的结构，主要是解析Resource注解啦。
private InjectionMetadata findResourceMetadata(String beanName, final Class<?> clazz, @Nullable PropertyValues pvs) {
// Fall back to class name as cache key, for backwards compatibility with custom callers.
String cacheKey = (StringUtils.hasLength(beanName) ? beanName : clazz.getName());
// Quick check on the concurrent map first, with minimal locking.
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);
}
metadata = buildResourceMetadata(clazz);//创建Resource注解注入元数据
this.injectionMetadataCache.put(cacheKey, metadata);
}
}
}
return metadata;
}
buildResourceMetadata构建Resource元数据
别看好像那么长，其实跟前面差不多，这次是会看是否有webService，ejb，Resource的属性注解和方法注解，有的话也封装成注入元数据InjectionMetadata返回。
private InjectionMetadata buildResourceMetadata(final Class<?> clazz) {
if (!AnnotationUtils.isCandidateClass(clazz, resourceAnnotationTypes)) {
return InjectionMetadata.EMPTY;
}
List<InjectionMetadata.InjectedElement> elements = new ArrayList<>();
Class<?> targetClass = clazz;
do {
final List<InjectionMetadata.InjectedElement> currElements = new ArrayList<>();
//查询是否有webService，ejb，Resource的属性注解，但是不支持静态属性
ReflectionUtils.doWithLocalFields(targetClass, field -> {
if (webServiceRefClass != null && field.isAnnotationPresent(webServiceRefClass)) {
if (Modifier.isStatic(field.getModifiers())) {
throw new IllegalStateException("@WebServiceRef annotation is not supported on static fields");
}
currElements.add(new WebServiceRefElement(field, field, null));
}
else if (ejbRefClass != null && field.isAnnotationPresent(ejbRefClass)) {
if (Modifier.isStatic(field.getModifiers())) {
throw new IllegalStateException("@EJB annotation is not supported on static fields");
}
currElements.add(new EjbRefElement(field, field, null));
}
else if (field.isAnnotationPresent(Resource.class)) {
if (Modifier.isStatic(field.getModifiers())) {
throw new IllegalStateException("@Resource annotation is not supported on static fields");
}
if (!this.ignoredResourceTypes.contains(field.getType().getName())) {
currElements.add(new ResourceElement(field, field, null));
}
}
});
//处理方法，桥接方法可以理解为解决老版本的类型转换问题，这里你就理解成就是普通方法
ReflectionUtils.doWithLocalMethods(targetClass, method -> {
Method bridgedMethod = BridgeMethodResolver.findBridgedMethod(method);
if (!BridgeMethodResolver.isVisibilityBridgeMethodPair(method, bridgedMethod)) {
return;
}
if (method.equals(ClassUtils.getMostSpecificMethod(method, clazz))) {
if (webServiceRefClass != null && bridgedMethod.isAnnotationPresent(webServiceRefClass)) {
if (Modifier.isStatic(method.getModifiers())) {
throw new IllegalStateException("@WebServiceRef annotation is not supported on static methods");
}
if (method.getParameterCount() != 1) {
throw new IllegalStateException("@WebServiceRef annotation requires a single-arg method: " + method);
}
PropertyDescriptor pd = BeanUtils.findPropertyForMethod(bridgedMethod, clazz);
currElements.add(new WebServiceRefElement(method, bridgedMethod, pd));
}
else if (ejbRefClass != null && bridgedMethod.isAnnotationPresent(ejbRefClass)) {
if (Modifier.isStatic(method.getModifiers())) {
throw new IllegalStateException("@EJB annotation is not supported on static methods");
}
if (method.getParameterCount() != 1) {
throw new IllegalStateException("@EJB annotation requires a single-arg method: " + method);
}
PropertyDescriptor pd = BeanUtils.findPropertyForMethod(bridgedMethod, clazz);
currElements.add(new EjbRefElement(method, bridgedMethod, pd));
}
else if (bridgedMethod.isAnnotationPresent(Resource.class)) {
if (Modifier.isStatic(method.getModifiers())) {//静态不行
throw new IllegalStateException("@Resource annotation is not supported on static methods");
}
Class<?>[] paramTypes = method.getParameterTypes();
if (paramTypes.length != 1) {//需要有一个参数
throw new IllegalStateException("@Resource annotation requires a single-arg method: " + method);
}
if (!this.ignoredResourceTypes.contains(paramTypes[0].getName())) {
PropertyDescriptor pd = BeanUtils.findPropertyForMethod(bridgedMethod, clazz);
currElements.add(new ResourceElement(method, bridgedMethod, pd));
}
}
}
});
elements.addAll(0, currElements);
targetClass = targetClass.getSuperclass();
}
while (targetClass != null && targetClass != Object.class);
return InjectionMetadata.forElements(elements, clazz);
}
InjectionMetadata的checkConfigMembers
这个也是一样，把元素注册进beanDefinition里。
public void checkConfigMembers(RootBeanDefinition beanDefinition) {
Set<InjectedElement> checkedElements = new LinkedHashSet<>(this.injectedElements.size());
for (InjectedElement element : this.injectedElements) {
Member member = element.getMember();
if (!beanDefinition.isExternallyManagedConfigMember(member)) {
beanDefinition.registerExternallyManagedConfigMember(member);
checkedElements.add(element);
if (logger.isTraceEnabled()) {
logger.trace("Registered injected element on class [" + this.targetClass.getName() + "]: " + element);
}
}
}
this.checkedElements = checkedElements;
}
光CommonAnnotationBeanPostProcessor就那么多了，其他的后面写吧。
好了，今天就到这里了，希望对学习理解有帮助，大神看见勿喷，仅为自己的学习理解，能力有限，请多包涵。
