咱们先说如果该办法是public,钻研一下其中的细节
@Service
public class TestServiceImpl {
@Transactional(rollbackFor = Exception.class)
public void trans1(){}
}
AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsAfterInitialization(),其中applyBeanPostProcessorsAfterInitialization()继承自AbstractAutoProxyCreator,上面是办法细节
public Object applyBeanPostProcessorsAfterInitialization(Object existingBean, String beanName)
throws BeansException {
Object result = existingBean;
//getBeanPostProcessors()是sptring boot启动时系统配置的BeanPostProcessor;其中有一个BeanPostProcessor叫做AnnotationAwareAspectJAutoProxyCreator;
for (BeanPostProcessor beanProcessor : getBeanPostProcessors()) {
//当遍历AnnotationAwareAspectJAutoProxyCreator时,执行其postProcessAfterInitialization()
Object current = beanProcessor.postProcessAfterInitialization(result, beanName);
if (current == null) {
return result;
}
result = current;
}
return result;
}
以下是AbstractAutoProxyCreator.postProcessAfterInitialization()细节:
public Object postProcessAfterInitialization(@Nullable Object bean, String beanName) throws BeansException {
if (bean != null) {
Object cacheKey = getCacheKey(bean.getClass(), beanName);
if (!this.earlyProxyReferences.contains(cacheKey)) {
//这个办法的重要逻辑是,依据beanName获取告诉列表,如果列表不为空,创立代理类;
return wrapIfNecessary(bean, beanName, cacheKey);
}
}
return bean;
}
图2
图3
protected Object wrapIfNecessary(Object bean, String beanName, Object cacheKey) {
//获取bean和beanName获取告诉列表.
Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null);
//本示例中testServiceImpl的specificInterceptors如图2所示;
//如果告诉列表不为空,则创立代理类
if (specificInterceptors != DO_NOT_PROXY) {
this.advisedBeans.put(cacheKey, Boolean.TRUE);
//执行具体创立代理逻辑,本示例中testServiceImpl的specificInterceptors如图3所示
Object proxy = createProxy(
bean.getClass(), beanName, specificInterceptors, new SingletonTargetSource(bean));
this.proxyTypes.put(cacheKey, proxy.getClass());
//间接返回
return proxy;
}
//如果没有匹配的告诉列表,返回一般的bean
this.advisedBeans.put(cacheKey, Boolean.FALSE);
return bean;
}
如果咱们测试用例中的 public 去掉呢?,咱们间接贴出后果:
图4
能够看到 specificInterceptors = null,也就是说并没有为其生成代理类。什么起因呢?咱们持续往下看:
//candidateAdvisors来自spring boot启动是配置的告诉列表
protected List<Advisor> findAdvisorsThatCanApply(
List<Advisor> candidateAdvisors, Class<?> beanClass, String beanName) {
ProxyCreationContext.setCurrentProxiedBeanName(beanName);
try {
//由AopUtils.findAdvisorsThatCanApply()执行具体的匹配逻辑
return AopUtils.findAdvisorsThatCanApply(candidateAdvisors, beanClass);
}
finally {
ProxyCreationContext.setCurrentProxiedBeanName(null);
}
}
咱们能够看到候选的告诉列表有24个
图5
public static boolean canApply(Pointcut pc, Class<?> targetClass, boolean hasIntroductions) {
IntroductionAwareMethodMatcher introductionAwareMethodMatcher = null;
if (methodMatcher instanceof IntroductionAwareMethodMatcher) {
introductionAwareMethodMatcher = (IntroductionAwareMethodMatcher) methodMatcher;
}
Set<Class<?>> classes = new LinkedHashSet<>();
if (!Proxy.isProxyClass(targetClass)) {
classes.add(ClassUtils.getUserClass(targetClass));
}
classes.addAll(ClassUtils.getAllInterfacesForClassAsSet(targetClass));
for (Class<?> clazz : classes) {
Method[] methods = ReflectionUtils.getAllDeclaredMethods(clazz);
for (Method method : methods) {
//因为introductionAwareMethodMatcher == null,所以methodMatcher.matches理论执行咱们的候选告诉器match办法;
if (introductionAwareMethodMatcher != null ?
introductionAwareMethodMatcher.matches(method, targetClass, hasIntroductions) :
methodMatcher.matches(method, targetClass)) {
return true;
}
}
}
return false;
}
图6
以TransactionAttributeSourcePointcut.matches()为例:
图7
public boolean matches(Method method, @Nullable Class<?> targetClass) {
if (targetClass != null && TransactionalProxy.class.isAssignableFrom(targetClass)) {
return false;
}
//图7为tas实例
TransactionAttributeSource tas = getTransactionAttributeSource();
return (tas == null || tas.getTransactionAttribute(method, targetClass) != null);
}
public TransactionAttribute getTransactionAttribute(Method method, @Nullable Class<?> targetClass) {
// We need to work it out.
TransactionAttribute txAttr = computeTransactionAttribute(method, targetClass);
return (tas == null || tas.getTransactionAttribute(method, targetClass) != null);
}
tas.getTransactionAttribute()会调用AbstractFallbackTransactionAttributeSource.computeTransactionAttribute():
protected TransactionAttribute computeTransactionAttribute(Method method, @Nullable Class<?> targetClass) {
// Don't allow no-public methods as required.
//通过下面这个正文看出不容许非public,因而返回 null;
if (allowPublicMethodsOnly() && !Modifier.isPublic(method.getModifiers())) {
return null;
}
}
此时下面的matches()返回false,最终AopUtils.findAdvisorsThatCanApply(candidateAdvisors, beanClass)返回空列表,这样一来AbstractAutoProxyCreator.wrapIfNecessary()中的 specificInterceptors 变量为null,也就没有方法创立代理类了!
最初,再抛出一个问题,如果一个service @Transactional办法既有 public,又有 no-pubic 会怎么呢?欢送一起探讨~~~
发表回复