- 创建事务信息流程图
- 处理回滚流程图
- 传播机制图
- AbstractPlatformTransactionManager的prepareSynchronization同步状态
- TransactionAspectSupport的prepareTransactionInfo准备事务信息
- TransactionAspectSupport的completeTransactionAfterThrowing处理异常
-
- DelegatingTransactionAttribute的rollbackOn是否可以回滚
-
- RuleBasedTransactionAttribute的rollbackOn
-
- DefaultTransactionAttribute的rollbackOn
- AbstractPlatformTransactionManager的rollback回滚
创建事务信息流程图
处理回滚流程图
传播机制图
AbstractPlatformTransactionManager的prepareSynchronization同步状态
设置各种线程私有变量的状态。
protected void prepareSynchronization(DefaultTransactionStatus status, TransactionDefinition definition) {
if (status.isNewSynchronization()) {
TransactionSynchronizationManager.setActualTransactionActive(status.hasTransaction());
TransactionSynchronizationManager.setCurrentTransactionIsolationLevel(
definition.getIsolationLevel() != TransactionDefinition.ISOLATION_DEFAULT ?
definition.getIsolationLevel() : null);
TransactionSynchronizationManager.setCurrentTransactionReadOnly(definition.isReadOnly());
TransactionSynchronizationManager.setCurrentTransactionName(definition.getName());
TransactionSynchronizationManager.initSynchronization();
}
}
都是当前事务相关的信息。
TransactionAspectSupport的prepareTransactionInfo准备事务信息
创建了一个TransactionInfo ，然后把事务管理器，事务注解属性，方法标识符，事务状态设置进去。然后绑定到当前线程私有变量里。
protected TransactionInfo prepareTransactionInfo(@Nullable PlatformTransactionManager tm,
@Nullable TransactionAttribute txAttr, String joinpointIdentification,
@Nullable TransactionStatus status) {
//创建事务信息
TransactionInfo txInfo = new TransactionInfo(tm, txAttr, joinpointIdentification);
if (txAttr != null) {
...
txInfo.newTransactionStatus(status);//设置新事务状态
}
else {
if (logger.isTraceEnabled()) {
logger.trace("No need to create transaction for [" + joinpointIdentification +
"]: This method is not transactional.");
}
}
...
txInfo.bindToThread();//事务信息绑定到当前线程
return txInfo;
}
TransactionAspectSupport的completeTransactionAfterThrowing处理异常
如果支持回滚的话就进行回滚，否则就处理提交，提交里面如果TransactionStatus.isRollbackOnly()=true的话也会进行回滚处理。
protected void completeTransactionAfterThrowing(@Nullable TransactionInfo txInfo, Throwable ex) {
if (txInfo != null && txInfo.getTransactionStatus() != null) {
if (logger.isTraceEnabled()) {
logger.trace("Completing transaction for [" + txInfo.getJoinpointIdentification() +
"] after exception: " + ex);
}
if (txInfo.transactionAttribute != null && txInfo.transactionAttribute.rollbackOn(ex)) {
try {
//进行回滚
txInfo.getTransactionManager().rollback(txInfo.getTransactionStatus());
}
catch (TransactionSystemException ex2) {
logger.error("Application exception overridden by rollback exception", ex);
ex2.initApplicationException(ex);
throw ex2;
}
catch (RuntimeException | Error ex2) {
logger.error("Application exception overridden by rollback exception", ex);
throw ex2;
}
}
else {
try {
txInfo.getTransactionManager().commit(txInfo.getTransactionStatus());
}
catch (TransactionSystemException ex2) {
logger.error("Application exception overridden by commit exception", ex);
ex2.initApplicationException(ex);
throw ex2;
}
catch (RuntimeException | Error ex2) {
logger.error("Application exception overridden by commit exception", ex);
throw ex2;
}
}
}
}
DelegatingTransactionAttribute的rollbackOn是否可以回滚
回滚对异常是有要求的。
@Override
public boolean rollbackOn(Throwable ex) {
return this.targetAttribute.rollbackOn(ex);
}
RuleBasedTransactionAttribute的rollbackOn
先处理回滚的规则，就是事务注解里的rollbackFor，rollbackForClassName，noRollbackFor，noRollbackForClassName属性。如果没有设置就会调用父类的rollbackOn。
@Override
public boolean rollbackOn(Throwable ex) {
if (logger.isTraceEnabled()) {
logger.trace("Applying rules to determine whether transaction should rollback on " + ex);
}
RollbackRuleAttribute winner = null;
int deepest = Integer.MAX_VALUE;
//处理设置的回滚规则
if (this.rollbackRules != null) {
for (RollbackRuleAttribute rule : this.rollbackRules) {
int depth = rule.getDepth(ex);
if (depth >= 0 && depth < deepest) {
deepest = depth;
winner = rule;
}
}
}
if (logger.isTraceEnabled()) {
logger.trace("Winning rollback rule is: " + winner);
}
// User superclass behavior (rollback on unchecked) if no rule matches.
if (winner == null) {
logger.trace("No relevant rollback rule found: applying default rules");
return super.rollbackOn(ex);
}
return !(winner instanceof NoRollbackRuleAttribute);
}
DefaultTransactionAttribute的rollbackOn
可以看到这里就是的异常，要么是RuntimeException的实例，要么是Error的实例。
@Override
public boolean rollbackOn(Throwable ex) {
return (ex instanceof RuntimeException || ex instanceof Error);
}
AbstractPlatformTransactionManager的rollback回滚
事务管理器根据事务状态来处理回滚。
@Override
public final void rollback(TransactionStatus status) throws TransactionException {
if (status.isCompleted()) {
throw new IllegalTransactionStateException(
"Transaction is already completed - do not call commit or rollback more than once per transaction");
}
DefaultTransactionStatus defStatus = (DefaultTransactionStatus) status;
processRollback(defStatus, false);
}
关键的就是processRollback，下次讲。
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。