事务注解 @Transactional 失效的3种场景及解决办法
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2021-04-14 09:36
Transactional失效场景
/**
* @author zhoujy
**/
@Component
public class TestServiceImpl {
@Resource
TestMapper testMapper;
@Transactional
void insertTestWrongModifier() {
int re = testMapper.insert(new Test(10,20,30));
if (re > 0) {
throw new NeedToInterceptException("need intercept");
}
testMapper.insert(new Test(210,20,30));
}
}
@Component
public class InvokcationService {
@Resource
private TestServiceImpl testService;
public void invokeInsertTestWrongModifier(){
//调用@Transactional标注的默认访问符方法
testService.insertTestWrongModifier();
}
}
@RunWith(SpringRunner.class)
@SpringBootTest
public class DemoApplicationTests {
@Resource
InvokcationService invokcationService;
@Test
public void testInvoke(){
invokcationService.invokeInsertTestWrongModifier();
}
}
TestServiceImpl#insertTestWrongModifier方法改为public的话将会正常开启事务，testMapper.insert(new Test(10,20,30));将会进行回滚。第二种失效场景
/**
* @author zhoujy
**/
@Component
public class TestServiceImpl implements TestService {
@Resource
TestMapper testMapper;
@Transactional
public void insertTestInnerInvoke() {
//正常public修饰符的事务方法
int re = testMapper.insert(new Test(10,20,30));
if (re > 0) {
throw new NeedToInterceptException("need intercept");
}
testMapper.insert(new Test(210,20,30));
}
public void testInnerInvoke(){
//类内部调用@Transactional标注的方法。
insertTestInnerInvoke();
}
}
@RunWith(SpringRunner.class)
@SpringBootTest
public class DemoApplicationTests {
@Resource
TestServiceImpl testService;
/**
* 测试内部调用@Transactional标注方法
*/
@Test
public void testInnerInvoke(){
//测试外部调用事务方法是否正常
//testService.insertTestInnerInvoke();
//测试内部调用事务方法是否正常
testService.testInnerInvoke();
}
}
第三种失效场景
/**
* @author zhoujy
**/
@Component
public class TestServiceImpl implements TestService {
@Resource
TestMapper testMapper;
@Transactional
public void insertTestCatchException() {
try {
int re = testMapper.insert(new Test(10,20,30));
if (re > 0) {
//运行期间抛异常
throw new NeedToInterceptException("need intercept");
}
testMapper.insert(new Test(210,20,30));
}catch (Exception e){
System.out.println("i catch exception");
}
}
}
@RunWith(SpringRunner.class)
@SpringBootTest
public class DemoApplicationTests {
@Resource
TestServiceImpl testService;
@Test
public void testCatchException(){
testService.insertTestCatchException();
}
}
@Transactional注解不起作用原理分析
第一种场景分析
@Transactional注解标注方法修饰符为非public时，@Transactional注解将会不起作用。这里分析 的原因是，@Transactional是基于动态代理实现的，@Transactional注解实现原理中分析了实现方法，在bean初始化过程中，对含有@Transactional标注的bean实例创建代理对象，这里就存在一个spring扫描@Transactional注解信息的过程，不幸的是源码中体现，标注@Transactional的方法如果修饰符不是public，那么就默认方法的@Transactional信息为空，那么将不会对bean进行代理对象创建或者不会对方法进行代理调用@Transactional注解实现原理中，介绍了如何判定一个bean是否创建代理对象，大概逻辑是。根据spring创建好一个aop切点BeanFactoryTransactionAttributeSourceAdvisor实例，遍历当前bean的class的方法对象，判断方法上面的注解信息是否包含@Transactional，如果bean任何一个方法包含@Transactional注解信息，那么就是适配这个BeanFactoryTransactionAttributeSourceAdvisor切点。则需要创建代理对象，然后代理逻辑为我们管理事务开闭逻辑。AopUtils#canApply(org.springframework.aop.Pointcut, java.lang.Class<?>, boolean)public static boolean canApply(Pointcut pc, Class<?> targetClass, boolean hasIntroductions) {
Assert.notNull(pc, "Pointcut must not be null");
if (!pc.getClassFilter().matches(targetClass)) {
return false;
}
MethodMatcher methodMatcher = pc.getMethodMatcher();
if (methodMatcher == MethodMatcher.TRUE) {
// No need to iterate the methods if we're matching any method anyway...
return true;
}
IntroductionAwareMethodMatcher introductionAwareMethodMatcher = null;
if (methodMatcher instanceof IntroductionAwareMethodMatcher) {
introductionAwareMethodMatcher = (IntroductionAwareMethodMatcher) methodMatcher;
}
//遍历class的方法对象
Set<Class<?>> classes = new LinkedHashSet<Class<?>>(ClassUtils.getAllInterfacesForClassAsSet(targetClass));
classes.add(targetClass);
for (Class<?> clazz : classes) {
Method[] methods = ReflectionUtils.getAllDeclaredMethods(clazz);
for (Method method : methods) {
if ((introductionAwareMethodMatcher != null &&
introductionAwareMethodMatcher.matches(method, targetClass, hasIntroductions)) ||
//适配查询方法上的@Transactional注解信息
methodMatcher.matches(method, targetClass)) {
return true;
}
}
}
return false;
}
AbstractFallbackTransactionAttributeSource#getTransactionAttributeAbstractFallbackTransactionAttributeSource#computeTransactionAttribute
protected TransactionAttribute computeTransactionAttribute(Method method, Class<?> targetClass) {
// Don't allow no-public methods as required.
//非public 方法，返回@Transactional信息一律是null
if (allowPublicMethodsOnly() && !Modifier.isPublic(method.getModifiers())) {
return null;
}
//后面省略.......
}
不创建代理对象
不进行代理调用
/**
* @author zhoujy
**/
@Component
public class TestServiceImpl implements TestService {
@Resource
TestMapper testMapper;
@Override
@Transactional
public void insertTest() {
int re = testMapper.insert(new Test(10,20,30));
if (re > 0) {
throw new NeedToInterceptException("need intercept");
}
testMapper.insert(new Test(210,20,30));
}
@Transactional
void insertTestWrongModifier() {
int re = testMapper.insert(new Test(10,20,30));
if (re > 0) {
throw new NeedToInterceptException("need intercept");
}
testMapper.insert(new Test(210,20,30));
}
}
CglibAopProxy.DynamicAdvisedInterceptor#intercept，有一个逻辑如下，目的是获取当前被代理对象的当前需要执行的method适配的aop逻辑。List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass);
AbstractFallbackTransactionAttributeSource#getTransactionAttributeAbstractFallbackTransactionAttributeSource#computeTransactionAttribute
第二种场景分析
既然事务管理是基于动态代理对象的代理逻辑实现的，那么如果在类内部调用类内部的事务方法，这个调用事务方法的过程并不是通过代理对象来调用的，而是直接通过this对象来调用方法，绕过的代理对象，肯定就是没有代理逻辑了。
/**
* @author zhoujy
**/
@Component
public class TestServiceImpl implements TestService {
@Resource
TestMapper testMapper;
@Resource
TestServiceImpl testServiceImpl;
@Transactional
public void insertTestInnerInvoke() {
int re = testMapper.insert(new Test(10,20,30));
if (re > 0) {
throw new NeedToInterceptException("need intercept");
}
testMapper.insert(new Test(210,20,30));
}
public void testInnerInvoke(){
//内部调用事务方法
testServiceImpl.insertTestInnerInvoke();
}
}
第三种场景分析
TransactionAspectSupport#invokeWithinTransactionprotected Object invokeWithinTransaction(Method method, Class<?> targetClass, final InvocationCallback invocation)
throws Throwable {
// If the transaction attribute is null, the method is non-transactional.
final TransactionAttribute txAttr = getTransactionAttributeSource().getTransactionAttribute(method, targetClass);
final PlatformTransactionManager tm = determineTransactionManager(txAttr);
final String joinpointIdentification = methodIdentification(method, targetClass);
if (txAttr == null || !(tm instanceof CallbackPreferringPlatformTransactionManager)) {
// Standard transaction demarcation with getTransaction and commit/rollback calls.
//开启事务
TransactionInfo txInfo = createTransactionIfNecessary(tm, txAttr, joinpointIdentification);
Object retVal = null;
try {
// This is an around advice: Invoke the next interceptor in the chain.
// This will normally result in a target object being invoked.
//反射调用业务方法
retVal = invocation.proceedWithInvocation();
}
catch (Throwable ex) {
// target invocation exception
//异常时，在catch逻辑中回滚事务
completeTransactionAfterThrowing(txInfo, ex);
throw ex;
}
finally {
cleanupTransactionInfo(txInfo);
}
//提交事务
commitTransactionAfterReturning(txInfo);
return retVal;
}
else {
//....................
}
}
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