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实际上,在spring的事务中,只要该类被设置为了事务代理:
拦截器都会创建一个TransactionInfo 对象:
TransactionInfo txInfo = new TransactionInfo(txAttr, method);
而且如果 只要被调用的方法设置了事务属性(txAttr),不管是什么属性都会调用:
txInfo.newTransactionStatus(this.transactionManager.getTransaction(txAttr));
根据该方法的事务属性(definition )的不同,this.transactionManager.getTransaction(txAttr)的返回值会有所不同(代码见AbstractPlatformTransactionManager),具体为以下几种情况:
1.当前没有事务时(即以下代码中的((HibernateTransactionObject) transaction).hasTransaction()返回false),会返回以下几种:
1 
// Check definition settings for new transaction.
2
if (definition.getTimeout() < TransactionDefinition.TIMEOUT_DEFAULT) {
3
throw new InvalidTimeoutException( " Invalid transaction timeout " , definition.getTimeout());
4
}
5
6 // No existing transaction found -> check propagation behavior to find out how to behave.
7 if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_MANDATORY) {
8 throw new IllegalTransactionStateException(
9 " Transaction propagation 'mandatory' but no existing transaction found " );
10 }
11 else if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_REQUIRED ||
12 definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_REQUIRES_NEW ||
13 definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_NESTED) {
14
if (debugEnabled) {
15 logger.debug( " Creating new transaction with name [ " + definition.getName() + " ] " );
16
}
17 doBegin(transaction, definition);
18 boolean newSynchronization = ( this .transactionSynchronization != SYNCHRONIZATION_NEVER);
19 return newTransactionStatus(definition, transaction, true , newSynchronization, debugEnabled, null );
20 }
21 else {
22 // Create "empty" transaction: no actual transaction, but potentially synchronization.
23 boolean newSynchronization = ( this .transactionSynchronization == SYNCHRONIZATION_ALWAYS);
24 return newTransactionStatus(definition, null , false , newSynchronization, debugEnabled, null );
25 }
26
// Check definition settings for new transaction. 2
if (definition.getTimeout() < TransactionDefinition.TIMEOUT_DEFAULT) {3
throw new InvalidTimeoutException( " Invalid transaction timeout " , definition.getTimeout());4
} 5
6
// No existing transaction found -> check propagation behavior to find out how to behave. 7
if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_MANDATORY) {8
throw new IllegalTransactionStateException(9
" Transaction propagation 'mandatory' but no existing transaction found " );10
} 11
else if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_REQUIRED || 12
definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_REQUIRES_NEW || 13
definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_NESTED) {14
if (debugEnabled) {15
logger.debug( " Creating new transaction with name [ " + definition.getName() + " ] " );16
} 17
doBegin(transaction, definition);18
boolean newSynchronization = ( this .transactionSynchronization != SYNCHRONIZATION_NEVER);19
return newTransactionStatus(definition, transaction, true , newSynchronization, debugEnabled, null );20
} 21
else {22
// Create "empty" transaction: no actual transaction, but potentially synchronization. 23
boolean newSynchronization = ( this .transactionSynchronization == SYNCHRONIZATION_ALWAYS);24
return newTransactionStatus(definition, null , false , newSynchronization, debugEnabled, null );25
} 26
2.当前有事务时
1 private TransactionStatus handleExistingTransaction(
2 TransactionDefinition definition, Object transaction, boolean debugEnabled)
3 throws TransactionException {
4
5 if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_NEVER) {
6 throw new IllegalTransactionStateException(
7 " Transaction propagation 'never' but existing transaction found " );
8 }
9
10 if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_NOT_SUPPORTED) {
11 if (debugEnabled) {
12 logger.debug( " Suspending current transaction " );
13 }
14 Object suspendedResources = suspend(transaction);
15 boolean newSynchronization = ( this .transactionSynchronization == SYNCHRONIZATION_ALWAYS);
16 return newTransactionStatus(
17 definition, null , false , newSynchronization, debugEnabled, suspendedResources);
18 }
19
20 if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_REQUIRES_NEW) {
21 if (debugEnabled) {
22 logger.debug( " Suspending current transaction, creating new transaction with name [ " +
23 definition.getName() + " ] " );
24 }
25 Object suspendedResources = suspend(transaction);
26 doBegin(transaction, definition);
27 boolean newSynchronization = ( this .transactionSynchronization != SYNCHRONIZATION_NEVER);
28 return newTransactionStatus(
29 definition, transaction, true , newSynchronization, debugEnabled, suspendedResources);
30 }
31
32 if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_NESTED) {
33 if ( ! isNestedTransactionAllowed()) {
34 throw new NestedTransactionNotSupportedException(
35 " Transaction manager does not allow nested transactions by default - " +
36 " specify 'nestedTransactionAllowed' property with value 'true' " );
37 }
38 if (debugEnabled) {
39 logger.debug( " Creating nested transaction with name [ " + definition.getName() + " ] " );
40 }
41 if (useSavepointForNestedTransaction()) {
42 // Create savepoint within existing Spring-managed transaction,
43 // through the SavepointManager API implemented by TransactionStatus.
44 // Usually uses JDBC 3.0 savepoints. Never activates Spring synchronization.
45 DefaultTransactionStatus status =
46 newTransactionStatus(definition, transaction, false , false , debugEnabled, null );
47 status.createAndHoldSavepoint();
48 return status;
49 }
50 else {
51 // Nested transaction through nested begin and commit/rollback calls.
52 // Usually only for JTA: Spring synchronization might get activated here
53 // in case of a pre-existing JTA transaction.
54 doBegin(transaction, definition);
55 boolean newSynchronization = ( this .transactionSynchronization != SYNCHRONIZATION_NEVER);
56 return newTransactionStatus(definition, transaction, true , newSynchronization, debugEnabled, null );
57 }
58 }
59
private TransactionStatus handleExistingTransaction(2
TransactionDefinition definition, Object transaction, boolean debugEnabled)3
throws TransactionException {4
5
if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_NEVER) {6
throw new IllegalTransactionStateException(7
" Transaction propagation 'never' but existing transaction found " );8
} 9
10
if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_NOT_SUPPORTED) {11
if (debugEnabled) {12
logger.debug( " Suspending current transaction " );13
} 14
Object suspendedResources = suspend(transaction);15
boolean newSynchronization = ( this .transactionSynchronization == SYNCHRONIZATION_ALWAYS);16
return newTransactionStatus(17
definition, null , false , newSynchronization, debugEnabled, suspendedResources);18
} 19
20
if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_REQUIRES_NEW) {21
if (debugEnabled) {22
logger.debug( " Suspending current transaction, creating new transaction with name [ " + 23
definition.getName() + " ] " );24
} 25
Object suspendedResources = suspend(transaction);26
doBegin(transaction, definition);27
boolean newSynchronization = ( this .transactionSynchronization != SYNCHRONIZATION_NEVER);28
return newTransactionStatus(29
definition, transaction, true , newSynchronization, debugEnabled, suspendedResources);30
} 31
32
if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_NESTED) {33
if ( ! isNestedTransactionAllowed()) {34
throw new NestedTransactionNotSupportedException(35
" Transaction manager does not allow nested transactions by default - " + 36
" specify 'nestedTransactionAllowed' property with value 'true' " );37
} 38
if (debugEnabled) {39
logger.debug( " Creating nested transaction with name [ " + definition.getName() + " ] " );40
} 41
if (useSavepointForNestedTransaction()) {42
// Create savepoint within existing Spring-managed transaction,43
// through the SavepointManager API implemented by TransactionStatus.44
// Usually uses JDBC 3.0 savepoints. Never activates Spring synchronization. 45
DefaultTransactionStatus status = 46
newTransactionStatus(definition, transaction, false , false , debugEnabled, null );47
status.createAndHoldSavepoint();48
return status;49
} 50
else {51
// Nested transaction through nested begin and commit/rollback calls.52
// Usually only for JTA: Spring synchronization might get activated here53
// in case of a pre-existing JTA transaction. 54
doBegin(transaction, definition);55
boolean newSynchronization = ( this .transactionSynchronization != SYNCHRONIZATION_NEVER);56
return newTransactionStatus(definition, transaction, true , newSynchronization, debugEnabled, null );57
} 58
} 59
最后,txInfo被绑定到当前线程上作为当前事务:
txInfo.bindToThread()
然后,调用实际的目标类的方法并捕捉异常:
try { // This is an around advice. // Invoke the next interceptor in the chain. // This will normally result in a target object being invoked. retVal = invocation.proceed(); } catch (Throwable ex) { // target invocation exception doCloseTransactionAfterThrowing(txInfo, ex); throw ex; } finally { doFinally(txInfo); } doCommitTransactionAfterReturning(txInfo); return retVal; } 另外一点,TransactionInfo的newTransactionStatus调用时如果参数的不是null,TransactionInfo.hasTransaction()方法返回true;
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