發生這種異常的case:
@Transactional
public void foo() {
try{
bar();
} catch (RuntimeException re) {
// caught but not throw further
}
}
@Transactional
public void bar() {
}
如果foo在調用bar的時候，bar拋出RuntimeException，Spring在bar return時將Transactional標記為Rollback only， 而foo捕獲了bar的RuntimeException，所以Spring將會commit foo的事務，但是foo和bar使用的是同一事務，因此在commit foo事務時，將會拋出UnexpectedRollbackException。注意：如果foo和bar在同一class中，不會出現這種情況，因為：
Since this mechanism is based on proxies, only 'external' method calls coming in through the proxy will be intercepted. This means that 'self-invocation', i.e. a method within the target object calling some other method of the target object, won't lead to an actual transaction at runtime even if the invoked method is marked with @Transactional!
可以通過配置log4j來debug Spring事務獲取情況：
To delve more into it I would turn up your log4j logging to debug and also look at what ExerciseModuleController is doing at line 91, e.g.: add a logger for org.springframework.transaction