很多朋友找 Bug 找了半天后来发现 @Transactional quietly 地挂掉了。其实 Spring 声明式事务的本质是 AOP 动态代理。

我们实际调用的 Service 方法是经过 CGLIB 或 JDK 提高过的代理对象，代理对象帮我们开启、提交或回滚事务。一旦绕过了代理对象，事务就形同虚设。

今天我们就结合真实的业务场景，盘点 Spring 事务失效的 8 种主要场景。针对大家反馈最多的 内部调用 和 try-catch异常我会给出最深度的解毒方案。

这是很多新手最容易犯的错，也是生产环境脏数据的头号元凶。

错误示范

java @Transactional public void createOrder { try { orderDao.insert;// 插入订单成功 inventoryDao.deduct);// 扣库存时报错抛异常 } catch { log.error;话说回来，// 异常被吞了什么也没做 } }

底层原理剖析

Spring 事务回滚的逻辑大致是这样的：

java // 代理逻辑伪代码 try { // 执领域务方法 method.invoke;// 如果没抛异常，提交事务 commit;} catch { // 捕获到异常，执行回滚 rollback;}

当你在业务代码里把异常 catch 住而且不再抛出对于 Spring 的代理拦截器业务方法正常执行结束了没抛异常，那自然是 "正常提交"。库存扣失败了但订单却提交了这就是经典的数据不一致。

解毒方案

从方案一来看，手动强制回滚

如果你的业务逻辑要求“即使扣库存失败，订单也要生成成功，但库存要回滚”。那就必须手动标记回滚状态：

java @Transactional public void createOrder { try { orderDao.insert;inventoryDao.deduct);} catch { log.error;// 主要，按理说，手动将当前事务标记为只回滚。**Spring会在提交时 abort** TransactionAspectSupport.currentTransactionStatus.setRollbackOnly;} }

方案二的观点是。直接抛出

如果你在面试中被问到事务失效，八十成左右会问这个。这也是掘金上争论最多的话题。怎么说呢，

java @Service public class OrderService {

public void placeOrder {
// **直接调用**，没走代理！this.createOrder;}
@Transactional
public void createOrder {
// 插入订单逻辑...
}

}

外部调用 orderService.placeOrder你会发现 createOrder 上的事务完全没反应。

路由分析这方面，代理对象 vs 原生对象

Spring容器里放的是 被代理提高过 的 OrderService$$CGLIB 对象。当外部调用 orderService.placeOrder 时走的是代理对象。

但进入 placeOrder 内后this指向的是当前原生对象而不是代理。 调用 this.createOrder 时直接调用原生方法AOP 拦截器根本没机会执行，事物自然不存在。

验证是否走协议？

java @Transactional public void createOrder { /***输出包含 $$EnhancerBySpringCGLIB说明走协议；***输出仅为com.example.OrderService说明原生对象***/ System.out.println.getName);}

深度解毒方案

说到🔥方案一，拆分类

把事件方法抽离另一个 Service 中。

java copyable=true lang=Java lineNumbers=false linenums=false highlight=13。14,15,16 @Service public class OrderService { @Autowired private InventoryService inventoryService;public void placeorder { inventoryservice.deductinventory;} }

至于🔥方案二，自注入

利于Spring解决循环依赖特性注入自己。

java copyable=true lang=Java lineNumbers=false linenums=false highlight=6。7,8 @Service public class OrderService { @Autowired private OrderServicesefProxy;//注入自己的协议对像 public void placeorder{//必须通过协议队列 selfProxy.createorder;} @transactional pubilcvoidcreateorder{...}

说到🔥方案三，AopContext强制暴露协议

在启动类开启 exposeProxy = true:

java copyable=true lang=Java lineNumbers=false linenums=false highlight=2 @EnableAspectJAutoProxy @SpringBootApplication public class Application {...}

call time:

lang-java copyable=true lineNumbers=false linenums=false highlight=4 publicvoidplaceorder{aopcontext.currentproxy).createorder;}}

这是硬性规定无商量余地。

lang-java copyable=true lineNumbers=false linenums=false highlight=2,4,6,8 @transactional privatevoidupdateprice{...}//fail @transactional protectedvoidupdateprice{...}//fail transactionalvoidupdateprice{...}//defaultpackagevisible。fail

源码实锤

Inspring源码 AbstractFallbackTransactionAttributeSource 中:

If&&!Modifier.isPublic)){returnnull;//directlynotresolveannotation}}

Spring官方认为事件应仅作于公共接口法.若果真非公共法必须开启aspectj编织模式,非常不推荐增加复杂度.

Many friends think default required is not high enough to change into requires new or nested results and events are mysteriously non-effective or deadlocked.

Typical failure scenario: supports and not supported)

@transactional publicvoiduppdatecache{ /*assumes re is a transaction but spring actually suspends any current transaction root event doesn't start!怎么说呢，*/}}

Typical failure scenario: requires new "false failure"

You think inner and outer methods both have transactions?说起来，see code:

@transactional{ inner;话说回来，//call internal requires new method inti=/;//exception thrown here}) @transactional publicvoidinner{ ... }}

deep solution)

unless you're very clear about nested event rollback point savepoint mechanism orwise blindly use @transactionaldefault))

if you really need requires_new please coordinate with "self injection" or "split classes" to ensure that new event is called by proxy object.

This problem is very common when taking over old projects but debugging can make people doubt ir life choices.

error demonstration)

project uses mysql table statement is:

createtable'ordertable')engine-myisamdefaultcharset=utf8;}

reason analysis)

'@transactioanl' bottom essence jdbc 'conn.setautocommit' + 'conn.commit'.but myisam storage engine root does not support transactions no matter how many times you send commit or rollback commands it will immediately land cannot be undone.)

solution query and modify table engine:

--view table engine show tablestatuslike'ordertable';--modify to innodb altertable'ordertable'engine-innodb;>

note这方面，mymysql default engine is innodb but if it's a dba hand built old table or migrated data must check carefully.

Now microservice read write separation projects are very common if you have multiple data sources primary library slave library business library a business library b only writing one @transactioanl will cause big trouble.

@configuration pubilcclassdatasourceconfig{ bean//ordersource bean//logsource }} serviceservicepubilcclasslogservice{

publicvoidsavelog{ /actual operations are logdatasource but events manager is orderdatasource!connection mismatch event fails or reports error directly/ logdao.insert;}}} }

reason analysis spring events manager core platformtransactionsmanager binds specific datasource @transactioanl default finds container type platformtransactionsmanager marked primary that if your operation anor datasource this datasource never been managed by this manager naturally event ineffective.)

deep solution must explicitly specify events manager bean name in annotation):

publicvoidsavelog{ logdao.insert;}} }

scenario one class didn't add serviceservice):

/forgot to add serviceserviceor component/ pubilcclassorderservice{ { ... }} /this class not even in spring container who proxy for you?/ }

scenario two traditional spring xml project annotation drive not enabled spring boot automatically configured enabletransactionmanagement but if your old project spring mvc + xml configuration must explicitly open):

xml这方面，

or configure on configuration):

(@configuration enabletransactionmanagement pubilcclassappconfig{ ... }} }

{ newthread-> {/sub-thread performs insertion/ ordersave;}).start，}} reason analysis spring events management relies threadlocal stores current thread database connection connectionholder).events bound main thread sub-thread run when obtaining connections simply cannot get main thread events context so sub-thread operations independent from events outside unable rollback.).

solution don't manually do newthreadin transaction methods. if asynchronous processing ensure use async configure separate transaction transmission mechanism or just encapsulate sub-thread operation as separate service let main thread wait result.)

。

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