正文
一、入口
package com.xiaojie.spring; import com.mysql.cj.jdbc.MysqlDataSource; import org.springframework.context.annotation.*; import org.springframework.jdbc.core.JdbcTemplate; import org.springframework.jdbc.datasource.DataSourceTransactionManager; import org.springframework.transaction.PlatformTransactionManager; import org.springframework.transaction.annotation.EnableTransactionManagement; import javax.sql.DataSource; /* * * @param null * 配置类 * @author xiaojie * @date 2021/8/24 * @return */ @Configuration @ComponentScan("com.xiaojie") @EnableTransactionManagement public class Config { /* * * 加载数据源 * @author xiaojie * @date 2021/8/24 * @return javax.sql.DataSource */ @Bean DataSource dataSource(){ MysqlDataSource mysqlDataSource = new MysqlDataSource(); mysqlDataSource.setURL("jdbc:mysql://127.0.0.1:3306/order?useUnicode=true&characterEncoding=UTF-8&rewriteBatchedStatements=true&allowMultiQueries=true&serverTimezone=Asia/Shanghai"); mysqlDataSource.setUser("root"); mysqlDataSource.setPassword("root"); // mysqlDataSource.setDatabaseName("order"); return mysqlDataSource; } /* * 加载事务管理器 * @author xiaojie * @date 2021/8/24 * @return org.springframework.transaction.PlatformTransactionManager */ @Bean PlatformTransactionManager platformTransactionManager(){ return new DataSourceTransactionManager(dataSource()); } /* *数据库连接 * @author xiaojie * @date 2021/8/24 * @return org.springframework.jdbc.core.JdbcTemplate */ @Bean JdbcTemplate jdbcTemplate(){ return new JdbcTemplate(dataSource()); } }
@EnableTransactionManagement 为事务的入口
二、流程图
三 、源码
AutoProxyRegistrar
//默认是代理模式 if (mode == AdviceMode.PROXY) { //注册InfrastructureAdvisorAutoProxyCreator.class类到ioc容器 AopConfigUtils.registerAutoProxyCreatorIfNecessary(registry); if ((Boolean) proxyTargetClass) { AopConfigUtils.forceAutoProxyCreatorToUseClassProxying(registry); return; } }
AopConfigUtils
private static BeanDefinition registerOrEscalateApcAsRequired( Class<?> cls, BeanDefinitionRegistry registry, @Nullable Object source) { Assert.notNull(registry, "BeanDefinitionRegistry must not be null"); if (registry.containsBeanDefinition(AUTO_PROXY_CREATOR_BEAN_NAME)) { BeanDefinition apcDefinition = registry.getBeanDefinition(AUTO_PROXY_CREATOR_BEAN_NAME); if (!cls.getName().equals(apcDefinition.getBeanClassName())) { int currentPriority = findPriorityForClass(apcDefinition.getBeanClassName()); int requiredPriority = findPriorityForClass(cls); if (currentPriority < requiredPriority) { apcDefinition.setBeanClassName(cls.getName()); } } return null; } RootBeanDefinition beanDefinition = new RootBeanDefinition(cls); beanDefinition.setSource(source); beanDefinition.getPropertyValues().add("order", Ordered.HIGHEST_PRECEDENCE); beanDefinition.setRole(BeanDefinition.ROLE_INFRASTRUCTURE); //AUTO_PROXY_CREATOR_BEAN_NAME=org.springframework.aop.config.internalAutoProxyCreator registry.registerBeanDefinition(AUTO_PROXY_CREATOR_BEAN_NAME, beanDefinition); return beanDefinition; }
上述注册完之后会将InfrastructureAdvisorAutoProxyCreator.class类注入到IOC中
beanId:org.springframework.aop.config.internalAutoProxyCreator
Class:InfrastructureAdvisorAutoProxyCreator.class
由类图InfrastructureAdvisorAutoProxyCreator.class继承了BeanPostProcessor同样会执行前置增强或者后置增强。
ProxyTransactionManagementConfiguration.class
//将TransactionInterceptor 类注入到IOC @Bean @Role(BeanDefinition.ROLE_INFRASTRUCTURE) public TransactionInterceptor transactionInterceptor(TransactionAttributeSource transactionAttributeSource) { TransactionInterceptor interceptor = new TransactionInterceptor(); interceptor.setTransactionAttributeSource(transactionAttributeSource); if (this.txManager != null) { interceptor.setTransactionManager(this.txManager); } return interceptor; }
再看BeanPostProcessor后置增强方法
然后就会发现跟AOP的代码是一样的
JdkDynamicAopProxy下invoke()
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { Object oldProxy = null; boolean setProxyContext = false; .........省略 // Get the interception chain for this method. List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass); // Check whether we have any advice. If we don't, we can fallback on direct // reflective invocation of the target, and avoid creating a MethodInvocation. if (chain.isEmpty()) { // We can skip creating a MethodInvocation: just invoke the target directly // Note that the final invoker must be an InvokerInterceptor so we know it does // nothing but a reflective operation on the target, and no hot swapping or fancy proxying. Object[] argsToUse = AopProxyUtils.adaptArgumentsIfNecessary(method, args); retVal = AopUtils.invokeJoinpointUsingReflection(target, method, argsToUse); } else { // We need to create a method invocation... MethodInvocation invocation = new ReflectiveMethodInvocation(proxy, target, method, args, targetClass, chain); // Proceed to the joinpoint through the interceptor chain. //由此进入proceed()方法 retVal = invocation.proceed(); } .........省略 }
ReflectiveMethodInvocation
public Object proceed() throws Throwable { // We start with an index of -1 and increment early. if (this.currentInterceptorIndex == this.interceptorsAndDynamicMethodMatchers.size() - 1) { return invokeJoinpoint(); } Object interceptorOrInterceptionAdvice = this.interceptorsAndDynamicMethodMatchers.get(++this.currentInterceptorIndex); if (interceptorOrInterceptionAdvice instanceof InterceptorAndDynamicMethodMatcher) { // Evaluate dynamic method matcher here: static part will already have // been evaluated and found to match. InterceptorAndDynamicMethodMatcher dm = (InterceptorAndDynamicMethodMatcher) interceptorOrInterceptionAdvice; Class<?> targetClass = (this.targetClass != null ? this.targetClass : this.method.getDeclaringClass()); if (dm.methodMatcher.matches(this.method, targetClass, this.arguments)) { return dm.interceptor.invoke(this); } else { // Dynamic matching failed. // Skip this interceptor and invoke the next in the chain. return proceed(); } } else { // It's an interceptor, so we just invoke it: The pointcut will have // been evaluated statically before this object was constructed. //此处用到了责任链设计模式+递归思想实现所有的通知增强 return ((MethodInterceptor) interceptorOrInterceptionAdvice).invoke(this); } }
MethodInterceptor
Object invoke(@Nonnull MethodInvocation invocation) throws Throwable;
TransactionInterceptor类下的invoke()方法
protected Object invokeWithinTransaction(Method method, @Nullable Class<?> targetClass, TransactionAspectSupport.InvocationCallback invocation) throws Throwable { ......省略 TransactionAspectSupport.TransactionInfo txInfo = this.createTransactionIfNecessary(ptm, txAttr, joinpointIdentification); Object retVal; try { //执行目标方法 retVal = invocation.proceedWithInvocation(); } catch (Throwable var20) { //发生异常 则执行事务回滚 this.completeTransactionAfterThrowing(txInfo, var20); throw var20; } finally { //将当前事务归还ThreadLocal<TransactionAspectSupport.TransactionInfo> this.cleanupTransactionInfo(txInfo); } if (retVal != null && vavrPresent && TransactionAspectSupport.VavrDelegate.isVavrTry(retVal)) { TransactionStatus status = txInfo.getTransactionStatus(); if (status != null && txAttr != null) { retVal = TransactionAspectSupport.VavrDelegate.evaluateTryFailure(retVal, txAttr, status); } } //提交事务 this.commitTransactionAfterReturning(txInfo); return retVal; .........省略 }
Spring 版本为5.3.9
