@Transactional传播属性

required有则有无则创建（默认）

说明：如果当前已经存在事务，那么加入该事务，如果不存在事务，创建一个事务，这是默认的传播属性值。

@Service
public class RequireMethodService {@AutowiredUserService userService;@Transactional(propagation = Propagation.REQUIRED)public void methodSon1() {User user = new User();user.setId(1);user.setUserName("A");userService.save(user);String act = TransactionSynchronizationManager.getCurrentTransactionName();System.out.println("Transaction1-----" + act);}@Transactional(propagation = Propagation.REQUIRED)public void methodSon2() {User user = new User();user.setId(2);user.setUserName("B");userService.save(user);String act = TransactionSynchronizationManager.getCurrentTransactionName();System.out.println("Transaction2-----" + act);}}

@Service
public class RequireService {@AutowiredRequireMethodService requireMethodService;@Transactionalpublic void service() {String act = TransactionSynchronizationManager.getCurrentTransactionName();System.out.println("begin-----" + act);requireMethodService.methodSon1();requireMethodService.methodSon2();} }

执行结果：事务是相同的

begin-----com.cn.service.propagation.require.RequireService.service
Transaction1-----com.cn.service.propagation.require.RequireService.service
Transaction2-----com.cn.service.propagation.require.RequireService.service

supports有则有无则无事务

如果当前已经存在事务，那么加入该事务，否则创建一个所谓的空事务（可以认为无事务执行）。

@Service
public class SupportMethodService {@AutowiredUserService userService;/*** 如果当前有事务则加入事务中，如果没有则什么都不做，相当于没事务。*/@Transactional(propagation = Propagation.SUPPORTS)public void methodSon1() {User user = new User();user.setId(1);user.setUserName("A");userService.save(user);throw new RuntimeException("异常");}}

@Service
public class SupportService {@AutowiredSupportMethodService supportMethodService;/*** @Transactional,开启事务后，service会和methodSon1公用一个事务，此时methodSon1会正常回滚；* * 如果这里没有开启，则methodSon1不会自己创建事务。此时methodSon1会不会回滚，数据插入到数据库；* */@Transactionalpublic void service() {supportMethodService.methodSon1();} }

执行结果：
SupportService在调用SupportMethodService的过程中
1. SupportService没有事务，则methodSon1也没有事务，不会回滚，数据插入到数据库。
2. SupportService有事务，则methodSon1加入到事务中，会回滚。

mandatory必须有事务

当前必须存在一个事务，否则抛出异常。

@Service
public class MandatoryMethodService {@AutowiredUserService userService;@Transactional(propagation = Propagation.MANDATORY)public void methodSon1() {User user = new User();user.setId(1);user.setUserName("A");userService.save(user);}@Transactional(propagation = Propagation.MANDATORY)public void methodSon2() {User user = new User();user.setId(2);user.setUserName("B");userService.save(user);}}

@Service
public class MandatoryService {@AutowiredMandatoryMethodService mandatoryMethodService;/*** 当前必须存在一个事务，否则抛出异常。* */
//  @Transactionalpublic void service() {//没有事务mandatoryMethodService.methodSon1();} }

执行结果：

org.springframework.transaction.IllegalTransactionStateException: No existing transaction found for transaction marked with propagation 'mandatory'at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:362) ~[spring-tx-5.3.6.jar:5.3.6]at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:595) ~[spring-tx-5.3.6.jar:5.3.6]at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:382) ~[spring-tx-5.3.6.jar:5.3.6]at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:119) ~[spring-tx-5.3.6.jar:5.3.6]at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.6.jar:5.3.6]at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:750) ~[spring-aop-5.3.6.jar:5.3.6]at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:692) ~[spring-aop-5.3.6.jar:5.3.6]

never 必须没有事务

如果当前存在事务，则抛出异常

@Service
public class NeverMethodService {@AutowiredUserService userService;@Transactional(propagation = Propagation.REQUIRED)public void methodSon1() {User user = new User();user.setId(1);user.setUserName("A");userService.save(user);}@Transactional(propagation = Propagation.NEVER)public void methodSon2() {User user = new User();user.setId(2);user.setUserName("B");userService.save(user);}}

@Service
public class NeverService {@AutowiredNeverMethodService neverMethodService;/*** 如果当前存在事务，则抛出异常，否则在无事务环境上执行代码。* * 如果调用方法上已经有事务，被调用方法上会报错。*/@Transactionalpublic void service() {//methodSon1创建了事务,但不会影响methodSon2neverMethodService.methodSon1();//methodSon2此时会报错，因为service()上已经开启了事务neverMethodService.methodSon2();} }

执行结果：

org.springframework.transaction.IllegalTransactionStateException: Existing transaction found for transaction marked with propagation 'never'at org.springframework.transaction.support.AbstractPlatformTransactionManager.handleExistingTransaction(AbstractPlatformTransactionManager.java:413) ~[spring-tx-5.3.6.jar:5.3.6]at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:352) ~[spring-tx-5.3.6.jar:5.3.6]at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:595) ~[spring-tx-5.3.6.jar:5.3.6]at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:382) ~[spring-tx-5.3.6.jar:5.3.6]at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:119) ~[spring-tx-5.3.6.jar:5.3.6]at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.6.jar:5.3.6]at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:750) ~[spring-aop-5.3.6.jar:5.3.6]at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:692) ~[spring-aop-5.3.6.jar:5.3.6]

requires_new新事务

REQUIRES_NEW新建一个事务，不管当前有没有事务，都新建一个独立的事务。

@Service
public class RequireNewMethodService {@AutowiredUserService userService;@Transactional(propagation = Propagation.REQUIRED)public void methodSon1() {User user = new User();user.setId(1);user.setUserName("A");userService.save(user);String act = TransactionSynchronizationManager.getCurrentTransactionName();System.out.println("Transaction1-----" + act);}@Transactional(propagation = Propagation.REQUIRES_NEW)public void methodSon2() {User user = new User();user.setId(2);user.setUserName("B");userService.save(user);String act = TransactionSynchronizationManager.getCurrentTransactionName();System.out.println("Transaction2-----" + act);}}

@Service
public class RequireNewService {@AutowiredRequireNewMethodService requireNewMethodService;/*** REQUIRES_NEW新建一个事务，不管当前有没有事务，都新建一个独立的事务。*/@Transactionalpublic void service() {String act = TransactionSynchronizationManager.getCurrentTransactionName();System.out.println("begin-----" + act);requireNewMethodService.methodSon1();requireNewMethodService.methodSon2();} }

执行结果：

begin-----com.cn.service.propagation.requiresnew.RequireNewService.service
Transaction1-----com.cn.service.propagation.requiresnew.RequireNewService.service
Transaction2-----com.cn.service.propagation.requiresnew.RequireNewMethodService.methodSon2

nested嵌套事务

1）methodSon2方法内部报错，则只会回滚methodSon2里面的。

2）methodSon2方法内部不报错，但是外面的调用方报错了，则methodSon2会跟着一起回滚。

3）methodSon2方法内部不报错，外面也不报错，则methodSon2和外面事务一起提交。

@Service
public class NestedMethodService {@AutowiredUserService userService;@Transactional(propagation = Propagation.REQUIRED)public void methodSon1() {User user = new User();user.setId(1);user.setUserName("A");userService.save(user);}@Transactional(propagation = Propagation.NESTED)public void methodSon2() {User user = new User();user.setId(2);user.setUserName("B");userService.save(user);throw new RuntimeException("methodSon2异常");}}


@Service
public class NestedService {@AutowiredNestedMethodService nestedMethodService;/*** methodSon2方法内部报错，则只会回滚methodSon2里面的。*/@Transactionalpublic void service() {nestedMethodService.methodSon1();try {nestedMethodService.methodSon2();} catch (Exception e) {e.printStackTrace();}} /*** methodSon1方法内部不报错，但是外面的methodSon2报错了，则methodSon1会跟着一起回滚。*/@Transactionalpublic void service2() {try {nestedMethodService.methodSon1();} catch (Exception e) {e.printStackTrace();}nestedMethodService.methodSon2();} }

总结：

在methodA()调用methodB()情况下

	REQUIRED	REQUIRES_NEW	NESTED
如果methodB()抛出异常，在methodA(）中没有try catch住	A、B都回滚	A、B都回滚	A、B都回滚
如果methodB() 抛出异常，在methodA(）中try catch住，没有重新抛出	A、B都回滚	A不回滚 B回滚	A不回滚 B回滚
如果methodB() 抛出异常，在methodA(）中try catch住，重新抛出	A、B都回滚	A、B都回滚	A、B都回滚
如果只有methodA抛出异常（先执行B，后执行A）	A、B都回滚	A回滚 B不回滚	A、B都回滚