com.example.demo.service;import

org.slf4j.Logger;

org.springframework.stereotype.Service;

import

org.springframework.transaction.annotation.Propagation;

import

org.springframework.transaction.annotation.Transactional;/***

若有外层事务，直接抛异常*/

LoggerFactory.getLogger(ThirdPayService.class);/***

调用第三方支付接口（模拟扣款）*

NEVER：必须非事务执行，有外层事务则抛异常*/@Transactional(propagation

String

模拟支付成功log.info("第三方支付接口调用完成：订单{}，扣款{}元，结果{}",

orderNo,

com.example.demo.service;import

import

com.example.demo.mapper.OrderMapper;

import

org.springframework.stereotype.Service;

import

org.springframework.transaction.annotation.Propagation;

import

org.springframework.transaction.annotation.Transactional;import

import

LoggerFactory.getLogger(OrderService.class);@Resourceprivate

OrderMapper

==========@Transactional(propagation

void

createOrderWithPayInTransaction(String

orderNo,

Order();order.setOrderNo(orderNo);order.setAmount(BigDecimal.valueOf(amount));order.setStatus("UNPAID");orderMapper.insertOrder(order);//

调用NEVER的第三方支付接口（有外层事务，预期抛异常）thirdPayService.callThirdPayApi(orderNo,

外层事务提交

注意：无@Transactional注解，即无外层事务public

void

createOrderWithPayWithoutTransaction(String

orderNo,

调用NEVER的第三方支付接口（无外层事务，正常执行）thirdPayService.callThirdPayApi(orderNo,

无外层事务：调用完成

com.example.demo.service.OrderService;

import

org.springframework.boot.test.context.SpringBootTest;

import

org.springframework.transaction.IllegalTransactionStateException;import

javax.annotation.Resource;@SpringBootTest

public

testNeverWithOuterTransaction()

{String

{orderService.createOrderWithPayInTransaction(orderNo,

199.99);}

IllegalTransactionStateException)

e.getMessage());//

testNeverWithoutOuterTransaction()

{String

System.currentTimeMillis();orderService.createOrderWithPayWithoutTransaction(orderNo,

199.99);}

“事务包裹第三方接口”

第三方支付接口调用完成：订单ORDER_1740000000000，扣款199.99元，结果SUCCESS

=====

“不想占用事务资源”，用NOT_SUPPORTED（挂起事务执行）；

若

“绝对禁止在事务中执行”，才用NEVER（有事务则抛异常）。

“绝对禁止事务执行”：有外层事务则抛异常，无则以非事务方式执行，与NOT_SUPPORTED（挂起事务执行）有本质区别；

适用场景：第三方接口调用、DDL

扣款接口：对方接口不允许被事务包裹（事务回滚可能导致接口重复调用，造成重复扣款）；这句话怎么理解