Spring聲明式事務註解之@EnableTransactionManagement解析

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
// 通過@Import導入TransactionManagementConfigurationSelector組件
@Import(TransactionManagementConfigurationSelector.class) 
public @interface EnableTransactionManagement { 
 boolean proxyTargetClass() default false; 
 AdviceMode mode() default AdviceMode.PROXY; 
 int order() default Ordered.LOWEST_PRECEDENCE;
}

public class TransactionManagementConfigurationSelector extends AdviceModeImportSelector<EnableTransactionManagement> {
 
 /**
  * {@inheritDoc}
  * @return {@link ProxyTransactionManagementConfiguration} or
  * {@code AspectJTransactionManagementConfiguration} for {@code PROXY} and
  * {@code ASPECTJ} values of {@link EnableTransactionManagement#mode()}, respectively
  */
 @Override
 protected String[] selectImports(AdviceMode adviceMode) {
  switch (adviceMode) {
   case PROXY:
    // 根據@EnableTransactionManagement的固定值PROXY，這裡會導入AutoProxyRegistrar組件和ProxyTransactionManagementConfiguration組件
    return new String[] {AutoProxyRegistrar.class.getName(), ProxyTransactionManagementConfiguration.class.getName()};
   case ASPECTJ:
    return new String[] {TransactionManagementConfigUtils.TRANSACTION_ASPECT_CONFIGURATION_CLASS_NAME};
   default:
    return null;
  }
 } 
}

InfrastructureAdvisorAutoProxyCreator
    --AbstractAdvisorAutoProxyCreator
        --AbstractAdvisorAutoProxyCreator
            --ProxyProcessorSupport
            --SmartInstantiationAwareBeanPostProcessor  // 跟AOP是原理是一樣的
                --InstantiationAwareBeanPostProcessor
                    --BeanPostProcessor
            --BeanFactoryAware

package org.springframework.transaction.annotation; 
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Role;
import org.springframework.transaction.config.TransactionManagementConfigUtils;
import org.springframework.transaction.interceptor.BeanFactoryTransactionAttributeSourceAdvisor;
import org.springframework.transaction.interceptor.TransactionAttributeSource;
import org.springframework.transaction.interceptor.TransactionInterceptor;
 
@Configuration
public class ProxyTransactionManagementConfiguration extends AbstractTransactionManagementConfiguration {
 
	
	/** 
		事務增強器(Advisor)，在事務類創建的時候，被AutoProxyRegistrar導入的組件InfrastructureAdvisorAutoProxyCreator攔截，
		InfrastructureAdvisorAutoProxyCreator攔截的邏就是增強事務類的事務方法，	而BeanFactoryTransactionAttributeSourceAdvisor作為增強器，
		與需要增強的方法(這裡是指被@Transactional標記的方法)進行匹配，匹配成功的增強器，最後轉成攔截器(MethodInterceptor,
		就是下面的TransactionInterceptor)，然後與目標方法一起在攔截器鏈中被執行，達到方法增強的效果；
		
		
		BeanFactoryTransactionAttributeSourceAdvisor的繼承關系如下：
		
		BeanFactoryTransactionAttributeSourceAdvisor
			--AbstractBeanFactoryPointcutAdvisor
				--AbstractPointcutAdvisor
					--PointcutAdvisor
						--Advisor
		
		AOP中AspectJPointcutAdvisor的繼承關系如下，與AbstractPointcutAdvisor一樣，都實現PointcutAdvisor
				--AspectJPointcutAdvisor
					--PointcutAdvisor
						--Advisor
	*/
	@Bean(name = TransactionManagementConfigUtils.TRANSACTION_ADVISOR_BEAN_NAME)
	@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
	public BeanFactoryTransactionAttributeSourceAdvisor transactionAdvisor() {
		BeanFactoryTransactionAttributeSourceAdvisor advisor = new BeanFactoryTransactionAttributeSourceAdvisor();
		advisor.setTransactionAttributeSource(transactionAttributeSource());
		advisor.setAdvice(transactionInterceptor());
		advisor.setOrder(this.enableTx.<Integer>getNumber("order"));
		return advisor;
	} 
 
	/**
		@Transactional註解的解析類；負責解析事務方法上@Transactional中的各個參數配置，解析的時機是在創建事務類之後被增強的時候，
		匹配事務方法的時候一起被解析瞭
		
		AnnotationTransactionAttributeSource的繼承關系如下：
		
		AnnotationTransactionAttributeSource
			--AbstractFallbackTransactionAttributeSource
				--TransactionAttributeSource
		通過方法org.springframework.transaction.interceptor.AbstractFallbackTransactionAttributeSource.getTransactionAttribute(Method, Class<?>)
		解析出事務信息TransactionAttribute；
		
		AnnotationTransactionAttributeSource在方法findTransactionAttribute(Class<?>)中依賴於SpringTransactionAnnotationParser在解析事務類時，
		綁定事務方法與增強器的時候進行@Transactional註解解析；
		
	*/
	@Bean
	@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
	public TransactionAttributeSource transactionAttributeSource() {
		return new AnnotationTransactionAttributeSource();
	}
 
	/**
		被@Transactional標記的事務方法的攔截器，實際是一個MethodInterceptor
		保存瞭事務屬性信息，事務管理器；
		在目標方法執行的時候；執行攔截器鏈；
	*/
	@Bean
	@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
	public TransactionInterceptor transactionInterceptor() {
		TransactionInterceptor interceptor = new TransactionInterceptor();
		interceptor.setTransactionAttributeSource(transactionAttributeSource());
		if (this.txManager != null) {
			interceptor.setTransactionManager(this.txManager);
		}
		return interceptor;
	}
}

protected TransactionAttribute parseTransactionAnnotation(AnnotationAttributes attributes) {
	RuleBasedTransactionAttribute rbta = new RuleBasedTransactionAttribute();
	Propagation propagation = attributes.getEnum("propagation");
	rbta.setPropagationBehavior(propagation.value());
	Isolation isolation = attributes.getEnum("isolation");
	rbta.setIsolationLevel(isolation.value());
	rbta.setTimeout(attributes.getNumber("timeout").intValue());
	rbta.setReadOnly(attributes.getBoolean("readOnly"));
	rbta.setQualifier(attributes.getString("value"));
	ArrayList<RollbackRuleAttribute> rollBackRules = new ArrayList<RollbackRuleAttribute>();
	Class<?>[] rbf = attributes.getClassArray("rollbackFor");
	for (Class<?> rbRule : rbf) {
		RollbackRuleAttribute rule = new RollbackRuleAttribute(rbRule);
		rollBackRules.add(rule);
	}
	String[] rbfc = attributes.getStringArray("rollbackForClassName");
	for (String rbRule : rbfc) {
		RollbackRuleAttribute rule = new RollbackRuleAttribute(rbRule);
		rollBackRules.add(rule);
	}
	Class<?>[] nrbf = attributes.getClassArray("noRollbackFor");
	for (Class<?> rbRule : nrbf) {
		NoRollbackRuleAttribute rule = new NoRollbackRuleAttribute(rbRule);
		rollBackRules.add(rule);
	}
	String[] nrbfc = attributes.getStringArray("noRollbackForClassName");
	for (String rbRule : nrbfc) {
		NoRollbackRuleAttribute rule = new NoRollbackRuleAttribute(rbRule);
		rollBackRules.add(rule);
	}
	rbta.getRollbackRules().addAll(rollBackRules);
	return rbta;
}

AutoProxyRegistrar
ProxyTransactionManagementConfiguration