回滚逻辑如下:
详细解析
根据@Transactional注解中rollbackFor、rollbackForClassName、noRollbackForClassName配置的值，找到最符合ex的异常类型，如果符合的异常类型不是NoRollbackRuleAttribute，则可以执行回滚。
如果@Transactional没有配置，则默认使用RuntimeException和Error异常。
代码如下：
@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;
//rollbackRules保存@Transactional注解中rollbackFor、rollbackForClassName、noRollbackForClassName配置的值
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.
//若@Transactional没有配置，默认调用父类的
if (winner == null) {
logger.trace("No relevant rollback rule found: applying default rules");
return super.rollbackOn(ex);
}
return !(winner instanceof NoRollbackRuleAttribute);
}
//super
@Override
public boolean rollbackOn(Throwable ex) {
return (ex instanceof RuntimeException || ex instanceof Error);
}
回滚处理
代码如下：
private void processRollback(DefaultTransactionStatus status) {
try {
try {
triggerBeforeCompletion(status);
//如果有安全点，回滚至安全点
if (status.hasSavepoint()) {
if (status.isDebug()) {
logger.debug("Rolling back transaction to savepoint");
}
status.rollbackToHeldSavepoint();
}
//如果是新事务，回滚事务
else if (status.isNewTransaction()) {
if (status.isDebug()) {
logger.debug("Initiating transaction rollback");
}
doRollback(status);
}
//如果有事务但不是新事务，则把标记事务状态，等事务链执行完毕后统一回滚
else if (status.hasTransaction()) {
if (status.isLocalRollbackOnly() || isGlobalRollbackOnParticipationFailure()) {
if (status.isDebug()) {
logger.debug("Participating transaction failed - marking existing transaction as rollback-only");
}
doSetRollbackOnly(status);
}
else {
if (status.isDebug()) {
logger.debug("Participating transaction failed - letting transaction originator decide on rollback");
}
}
}
else {
logger.debug("Should roll back transaction but cannot - no transaction available");
}
}
catch (RuntimeException ex) {
triggerAfterCompletion(status, TransactionSynchronization.STATUS_UNKNOWN);
throw ex;
}
catch (Error err) {
triggerAfterCompletion(status, TransactionSynchronization.STATUS_UNKNOWN);
throw err;
}
triggerAfterCompletion(status, TransactionSynchronization.STATUS_ROLLED_BACK);
}
finally {
//清空记录的资源并将挂起的资源恢复
cleanupAfterCompletion(status);
}
}
事务提交逻辑如下：
代码如下：
@Override
public final void commit(TransactionStatus status) throws TransactionException {
//1. 判断事务是不是已经完成
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;
//2. 如果在事务链中已经被标记回滚，那么不会尝试提交事务，直接回滚，不过我没找到在哪设置这个值
if (defStatus.isLocalRollbackOnly()) {
if (defStatus.isDebug()) {
logger.debug("Transactional code has requested rollback");
}
processRollback(defStatus);
return;
}
//3. shouldCommitOnGlobalRollbackOnly()默认返回false，isGlobalRollbackOnly是在嵌入事务回滚的时候赋值的
if (!shouldCommitOnGlobalRollbackOnly() && defStatus.isGlobalRollbackOnly()) {
if (defStatus.isDebug()) {
logger.debug("Global transaction is marked as rollback-only but transactional code requested commit");
}
processRollback(defStatus);
// Throw UnexpectedRollbackException only at outermost transaction boundary
// or if explicitly asked to.
if (status.isNewTransaction() || isFailEarlyOnGlobalRollbackOnly()) {
throw new UnexpectedRollbackException(
"Transaction rolled back because it has been marked as rollback-only");
}
return;
}
//4. 提交事务
processCommit(defStatus);
}
