spring的事务传播机制
spring的事务传播机制
嫌弃内容代码复杂的可直接看思维导图大纲即可
基本概念
指的就是当一个事务方法被另一个事务方法调用时，这个事务方法应该如何进行
七种行为和测试
PROPAGATION_REQUIRED
默认，当前存在事务，则加入该事务；不存在事务，创建新事务。
public class PropagationService {
@Autowired
private
PropagationMapper propagationMapper;
@Autowired
@Lazy
PropagationService propagationService;
@Transactional(rollbackFor = Exception.class)
public void insertPropagationA() throws Exception {
Propagation propagationA = Propagation.builder()
.type("Propagation.REQUIRED")
.comment("propagationA").build();
propagationMapper.insert(propagationA);
propagationServiceSelf.insertPropagationB();
throw new Exception();
}
@Transactional(rollbackFor = Exception.class,propagation = org.springframework.transaction.annotation.Propagation.REQUIRED)
public void insertPropagationB() throws Exception {
Propagation propagationB = Propagation.builder()
.type("Propagation.REQUIRED")
.comment("propagationB").build();
Propagation propagationBB = Propagation.builder()
.type("Propagation.REQUIRED")
.comment("propagationBB").build();
propagationMapper.insert(propagationB);
propagationMapper.insert(prop
@Test
//Given A传播行为required 和B为required,WHE A发生异常,THEN A插入失败，B插入失败
public void testRequired() throws Exception {
propagationService.insertPropagationA();
}
PROPAGATION_REQUIRED_NEW
始终以新的事务运行，当前存在事务，则挂起原事务；不存在事务，创建新事务
@Test
//Given 同样代码更改B为required_new, WHE A发生异常, THEN B插入成功，A插入失败
public void testRequiredNew() throws Exception {
propagationService.insertPropagationA();
}
PROPAGATION_SUPPORTS
支持当前事务。当前存在事务，则支持该事务；不存在事务，以非事务方式执行
@Test
//Given 更改B为required_supports, A不开启事物， WHE B发生异常, THEN A、B插入成功BB失败;A开启事物因为有异常发生全失败
public void testRequiredSupports() throws Exception {
propagationService.insertPropagationA();
}
//@Transactional(rollbackFor = Exception.class)
public void insertPropagationA() throws Exception {
Propagation propagationA = Propagation.builder()
.type("Propagation.REQUIRED")
.comment("propagationA").build();
propagationMapper.insert(propagationA);
propagationServiceSelf.insertPropagationB();
throw new Exception();
}
@Transactional(rollbackFor = Exception.class,propagation = org.springframework.transaction.annotation.Propagation.SUPPORTS)
public void insertPropagationB() throws Exception {
Propagation propagationB = Propagation.builder()
.type("Propagation.REQUIRED")
.comment("propagationB").build();
Propagation propagationBB = Propagation.builder()
.type("Propagation.REQUIRED")
.comment("propagationBB").build();
propagationMapper.insert(propagationB);
int a = 1/0;
propagationMapper.insert(propagationBB);
}
PROPAGATION_NO_SUPPORTED
非事务方式执行，当前存在事务，则挂起该事务
@Test
//Given 更改B为required_not_supports, A开启事物， WHEN A发生异常, THEN A插入失败、B插入成功
public void testRequiredNotSupports() throws Exception {
propagationService.insertPropagationA();
}
@Transactional(rollbackFor = Exception.class)
public void insertPropagationA() throws Exception {
Propagation propagationA = Propagation.builder()
.type("Propagation.REQUIRED")
.comment("propagationA").build();
propagationMapper.insert(propagationA);
propagationServiceSelf.insertPropagationB();
throw new Exception();
}
@Transactional(rollbackFor = Exception.class,propagation = org.springframework.transaction.annotation.Propagation.NOT_SUPPORTED)
public void insertPropagationB() throws Exception {
Propagation propagationB = Propagation.builder()
.type("Propagation.REQUIRED")
.comment("propagationB").build();
Propagation propagationBB = Propagation.builder()
.type("Propagation.REQUIRED")
.comment("propagationBB").build();
propagationMapper.insert(propagationB);
propagationMapper.insert(propagationBB);
}
PROPAGATION_NEVER
非事务方式执行，当前存在事务，则抛出异常();
org.springframework.transaction.IllegalTransactionStateException: Existing transaction found for transaction marked with propagation 'never'
at org.springframework.transaction.support.AbstractPlatformTransactionManager.handleExistingTransaction(AbstractPlatformTransactionManager.java:413)
@Transactional(rollbackFor = Exception.class)
public void insertPropagationA() throws Exception {
Propagation propagationA = Propagation.builder()
.type("Propagation.REQUIRED")
.comment("propagationA").build();
propagationMapper.insert(propagationA);
propagationServiceSelf.insertPropagationB();
//throw new Exception();
}
@Transactional(rollbackFor = Exception.class,propagation = org.springframework.transaction.annotation.Propagation.NEVER)
public void insertPropagationB() throws Exception {
Propagation propagationB = Propagation.builder()
.type("Propagation.REQUIRED")
.comment("propagationB").build();
Propagation propagationBB = Propagation.builder()
.type("Propagation.REQUIRED")
.comment("propagationBB").build();
propagationMapper.insert(propagationB);
propagationMapper.insert(propagationBB);
}
@Test
//Given 更改B为required_never, A开启事物， 调用方法B时报错
public void testRequiredNever() throws Exception {
propagationService.insertPropagationA();
}
PROPAGATION_NESTED
当前存在事务，则嵌套在该事务下起新事务执行；不存在事务，创建新事务。
@Test
//Given 更改B为required_nested, A开启事物， 调用方法B,后抛出异常,都失败;A开启事物，调用方法B，B抛出异常，A catch，A成功，B失败
public void testRequiredNested() throws Exception {
propagationService.insertPropagationA();
}
@Transactional(rollbackFor = Exception.class)
public void insertPropagationA() throws Exception {
Propagation propagationA = Propagation.builder()
.type("Propagation.REQUIRED")
.comment("propagationA").build();
propagationMapper.insert(propagationA);
try{
propagationServiceSelf.insertPropagationB();
}catch(Exception e){
}
}
@Transactional(rollbackFor = Exception.class,propagation = org.springframework.transaction.annotation.Propagation.NESTED)
public void insertPropagationB() throws Exception {
Propagation propagationB = Propagation.builder()
.type("Propagation.REQUIRED")
.comment("propagationB").build();
Propagation propagationBB = Propagation.builder()
.type("Propagation.REQUIRED")
.comment("propagationBB").build();
propagationMapper.insert(propagationB);
int a = 1/0;
propagationMapper.insert(propagationBB);
}
PROPAGATION_MANDATORY
事务方式运行，当前不存在事务，则抛出异常
org.springframework.transaction.IllegalTransactionStateException: No existing transaction found for transaction marked with propagation 'mandatory'
at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:362)
//@Transactional(rollbackFor = Exception.class)
public void insertPropagationA() throws Exception {
Propagation propagationA = Propagation.builder()
.type("Propagation.REQUIRED")
.comment("propagationA").build();
propagationMapper.insert(propagationA);
propagationServiceSelf.insertPropagationB();
}
@Transactional(rollbackFor = Exception.class,propagation = org.springframework.transaction.annotation.Propagation.MANDATORY)
public void insertPropagationB() throws Exception {
Propagation propagationB = Propagation.builder()
.type("Propagation.REQUIRED")
.comment("propagationB").build();
Propagation propagationBB = Propagation.builder()
.type("Propagation.REQUIRED")
.comment("propagationBB").build();
propagationMapper.insert(propagationB);
propagationMapper.insert(propagationBB);
}
@Test
//Given 更改B为required_mandatory, WHEN A不开启事物，调用方法B, THEN调用B抛出异常;
public void testRequiredMandatory() throws Exception {
propagationService.insertPropagationA();
}
Transactional失效
spring的事物是基于AOP代理实现的，也就是说背@Transactional修饰的方法所在类会有一个代理类，通过这个代理类实现的。并且也需要底层数据库支持事物，还需要在同一个库中，多个方法运行调用需要在同一个线程中。基于这情况大概失效场景分为两部分
非代理类方向
-
数据库引擎不支持索引如MyISAm
-
数据源未配置事物管理器
-
数据库分布式部署，需要Seata技术解决
-
多线程，两个事务方法不在同一个线程
代理类方向
-
类未交给spring，代理自然无法生成
-
自身调用，相当于this，代理类未生效
-
事务方法修饰如非public、final、static修饰导致不能被代理
-
异常类型错误，声明式事务默认对runtimeException、Error才可以触发回滚
-
对抛出的异常，catch后处理不当。如吞了异常。
-
设置了错误的传播行为
