Seata

官网： https://seata.io/zh-cn/index.html

是什么？

Seata 是一款开源的分布式事务解决方案，致力于提供高性能和简单易用的分布式事务服务。Seata 将为用户提供了 AT、TCC、SAGA 和 XA 事务模式，为用户打造一站式的分布式解决方案。

TC (Transaction Coordinator) - 事务协调者

维护全局和分支事务的状态，驱动全局事务提交或回滚。

TM (Transaction Manager) - 事务管理器

定义全局事务的范围：开始全局事务、提交或回滚全局事务。

RM (Resource Manager) - 资源管理器

管理分支事务处理的资源，与TC交谈以注册分支事务和报告分支事务的状态，并驱动分支事务提交或回滚。

四种模式

AT

前提

• 基于支持本地 ACID 事务的关系型数据库。
• Java 应用，通过 JDBC 访问数据库。

整体机制

两阶段提交协议的演变：

• 一阶段：业务数据和回滚日志记录在同一个本地事务中提交，释放本地锁和连接资源。
• 二阶段：
  • 提交异步化，非常快速地完成。
  • 回滚通过一阶段的回滚日志进行反向补偿。

写隔离

• 一阶段本地事务提交前，需要确保先拿到 全局锁 。
• 拿不到 全局锁 ，不能提交本地事务。
• 拿 全局锁 的尝试被限制在一定范围内，超出范围将放弃，并回滚本地事务，释放本地锁。

以一个示例来说明：

两个全局事务 tx1 和 tx2，分别对 a 表的 m 字段进行更新操作，m 的初始值 1000。

tx1 先开始，开启本地事务，拿到本地锁，更新操作 m = 1000 - 100 = 900。本地事务提交前，先拿到该记录的 全局锁 ，本地提交释放本地锁。 tx2 后开始，开启本地事务，拿到本地锁，更新操作 m = 900 - 100 = 800。本地事务提交前，尝试拿该记录的 全局锁 ，tx1 全局提交前，该记录的全局锁被 tx1 持有，tx2 需要重试等待 全局锁 。

tx1 二阶段全局提交，释放 全局锁 。tx2 拿到 全局锁 提交本地事务。

如果 tx1 的二阶段全局回滚，则 tx1 需要重新获取该数据的本地锁，进行反向补偿的更新操作，实现分支的回滚。

此时，如果 tx2 仍在等待该数据的 全局锁，同时持有本地锁，则 tx1 的分支回滚会失败。分支的回滚会一直重试，直到 tx2 的 全局锁 等锁超时，放弃 全局锁 并回滚本地事务释放本地锁，tx1 的分支回滚最终成功。

因为整个过程 全局锁 在 tx1 结束前一直是被 tx1 持有的，所以不会发生 脏写 的问题。

读隔离

在数据库本地事务隔离级别 读已提交（Read Committed） 或以上的基础上，Seata（AT 模式）的默认全局隔离级别是 读未提交（Read Uncommitted） 。

如果应用在特定场景下，必需要求全局的 读已提交 ，目前 Seata 的方式是通过 SELECT FOR UPDATE 语句的代理。

SELECT FOR UPDATE 语句的执行会申请 全局锁 ，如果 全局锁 被其他事务持有，则释放本地锁（回滚 SELECT FOR UPDATE 语句的本地执行）并重试。这个过程中，查询是被 block 住的，直到 全局锁 拿到，即读取的相关数据是 已提交 的，才返回。

出于总体性能上的考虑，Seata 目前的方案并没有对所有 SELECT 语句都进行代理，仅针对 FOR UPDATE 的 SELECT 语句。

TCC

回顾总览中的描述：一个分布式的全局事务，整体是 两阶段提交 的模型。全局事务是由若干分支事务组成的，分支事务要满足 两阶段提交 的模型要求，即需要每个分支事务都具备自己的：

• 一阶段 prepare 行为
• 二阶段 commit 或 rollback 行为

根据两阶段行为模式的不同，我们将分支事务划分为 Automatic (Branch) Transaction Mode 和 Manual (Branch) Transaction Mode.

AT 模式（参考链接 TBD）基于 支持本地 ACID 事务 的 关系型数据库：

• 一阶段 prepare 行为：在本地事务中，一并提交业务数据更新和相应回滚日志记录。
• 二阶段 commit 行为：马上成功结束，自动 异步批量清理回滚日志。
• 二阶段 rollback 行为：通过回滚日志，自动 生成补偿操作，完成数据回滚。

相应的，TCC 模式，不依赖于底层数据资源的事务支持：

• 一阶段 prepare 行为：调用 自定义 的 prepare 逻辑。
• 二阶段 commit 行为：调用 自定义 的 commit 逻辑。
• 二阶段 rollback 行为：调用 自定义 的 rollback 逻辑。

所谓 TCC 模式，是指支持把 自定义 的分支事务纳入到全局事务的管理中。

SAGA

Saga模式是SEATA提供的长事务解决方案，在Saga模式中，业务流程中每个参与者都提交本地事务，当出现某一个参与者失败则补偿前面已经成功的参与者，一阶段正向服务和二阶段补偿服务都由业务开发实现。

适用场景：

• 业务流程长、业务流程多
• 参与者包含其它公司或遗留系统服务，无法提供 TCC 模式要求的三个接口

优势：

• 一阶段提交本地事务，无锁，高性能
• 事件驱动架构，参与者可异步执行，高吞吐
• 补偿服务易于实现

缺点：

• 不保证隔离性（应对方案见用户文档）

XA

暂略

Seata1.6.x配置

打开{seata_home}\\seata-server-1.6.0\\seata\\conf\\application.yml

#  Copyright 1999-2019 Seata.io Group.
#
#  Licensed under the Apache License, Version 2.0 (the "License");
#  you may not use this file except in compliance with the License.
#  You may obtain a copy of the License at
#
#  http://www.apache.org/licenses/LICENSE-2.0
#
#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an "AS IS" BASIS,
#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#  See the License for the specific language governing permissions and
#  limitations under the License.server:port: 7091spring:application:name: seata-serverlogging:config: classpath:logback-spring.xmlfile:path: ${user.home}/logs/seataextend:logstash-appender:destination: 127.0.0.1:4560kafka-appender:bootstrap-servers: 127.0.0.1:9092topic: logback_to_logstashconsole:user:username: seatapassword: seataseata:config:# support: nacos, consul, apollo, zk, etcd3type: nacosnacos:server-addr: localhost:8848namespace: dfa2d8f9-2c8f-4775-8cea-04676046caecgroup: DEFAULT_GROUPusername: nacospassword: nacosdata-id: seataServer.propertiesregistry:# support: nacos, eureka, redis, zk, consul, etcd3, sofatype: nacosnacos:application: seata-serverserver-addr: localhost:8848namespace: dfa2d8f9-2c8f-4775-8cea-04676046caecgroup: DEFAULT_GROUPcluster: defaultusername: nacospassword: nacosstore:# support: file 、 db 、 redismode: dbdb:datasource: druiddb-type: mysqldriver-class-name: com.mysql.jdbc.Driverurl: jdbc:mysql://127.0.0.1:3306/seata?serverTimezone=GMT%2B8user: rootpassword: 123456min-conn: 5max-conn: 100global-table: global_tablebranch-table: branch_tablelock-table: lock_tabledistributed-lock-table: distributed_lockquery-limit: 100  max-wait: 5000
#  server:
#    service-port: 8091 #If not configured, the default is '${server.port} + 1000'security:secretKey: SeataSecretKey0c382ef121d778043159209298fd40bf3850a017tokenValidityInMilliseconds: 1800000ignore:urls: /,//*.css,//*.js,//*.html,//*.map,//*.svg,//*.png,//*.ico,/console-fe/public/,/api/v1/auth/login

在nacos新建命名空间seata

在对应的seata命名空间下新建配置文件seataServer.properties

#For details about configuration items, see https://seata.io/zh-cn/docs/user/configurations.html
#Transport configuration, for client and server
transport.type=TCP
transport.server=NIO
transport.heartbeat=true
transport.enableTmClientBatchSendRequest=false
transport.enableRmClientBatchSendRequest=true
transport.enableTcServerBatchSendResponse=false
transport.rpcRmRequestTimeout=30000
transport.rpcTmRequestTimeout=30000
transport.rpcTcRequestTimeout=30000
transport.threadFactory.bossThreadPrefix=NettyBoss
transport.threadFactory.workerThreadPrefix=NettyServerNIOWorker
transport.threadFactory.serverExecutorThreadPrefix=NettyServerBizHandler
transport.threadFactory.shareBossWorker=false
transport.threadFactory.clientSelectorThreadPrefix=NettyClientSelector
transport.threadFactory.clientSelectorThreadSize=1
transport.threadFactory.clientWorkerThreadPrefix=NettyClientWorkerThread
transport.threadFactory.bossThreadSize=1
transport.threadFactory.workerThreadSize=default
transport.shutdown.wait=3
transport.serialization=seata
transport.compressor=none
#Transaction routing rules configuration, only for the client
service.vgroupMapping.mygroup=default
#If you use a registry, you can ignore it
service.default.grouplist=127.0.0.1:8091
service.enableDegrade=false
service.disableGlobalTransaction=false
#Transaction rule configuration, only for the client
client.rm.asyncCommitBufferLimit=10000
client.rm.lock.retryInterval=10
client.rm.lock.retryTimes=30
client.rm.lock.retryPolicyBranchRollbackOnConflict=true
client.rm.reportRetryCount=5
client.rm.tableMetaCheckEnable=true
client.rm.tableMetaCheckerInterval=60000
client.rm.sqlParserType=druid
client.rm.reportSuccessEnable=false
client.rm.sagaBranchRegisterEnable=false
client.rm.sagaJsonParser=fastjson
client.rm.tccActionInterceptorOrder=-2147482648
client.tm.commitRetryCount=5
client.tm.rollbackRetryCount=5
client.tm.defaultGlobalTransactionTimeout=60000
client.tm.degradeCheck=false
client.tm.degradeCheckAllowTimes=10
client.tm.degradeCheckPeriod=2000
client.tm.interceptorOrder=-2147482648
client.undo.dataValidation=true
client.undo.logSerialization=jackson
client.undo.onlyCareUpdateColumns=true
server.undo.logSaveDays=7
server.undo.logDeletePeriod=86400000
client.undo.logTable=undo_log
client.undo.compress.enable=true
client.undo.compress.type=zip
client.undo.compress.threshold=64k
#For TCC transaction mode
tcc.fence.logTableName=tcc_fence_log
tcc.fence.cleanPeriod=1h
#Log rule configuration, for client and server
log.exceptionRate=100
#Transaction storage configuration, only for the server. The file, db, and redis configuration values are optional.
store.mode=db
store.lock.mode=db
store.session.mode=db
#Used for password encryption#If `store.mode,store.lock.mode,store.session.mode` are not equal to `file`, you can remove the configuration block.#These configurations are required if the `store mode` is `db`. If `store.mode,store.lock.mode,store.session.mode` are not equal to `db`, you can remove the configuration block.
store.db.datasource=druid
store.db.dbType=mysql
store.db.driverClassName=com.mysql.jdbc.Driver
store.db.url=jdbc:mysql://127.0.0.1:3306/seata?useUnicode=true&rewriteBatchedStatements=true
store.db.user=root
store.db.password=123456
store.db.minConn=5
store.db.maxConn=30
store.db.globalTable=global_table
store.db.branchTable=branch_table
store.db.distributedLockTable=distributed_lock
store.db.queryLimit=100
store.db.lockTable=lock_table
store.db.maxWait=5000
#These configurations are required if the `store mode` is `redis`. If `store.mode,store.lock.mode,store.session.mode` are not equal to `redis`, you can remove the configuration block.#Transaction rule configuration, only for the server
server.recovery.committingRetryPeriod=1000
server.recovery.asynCommittingRetryPeriod=1000
server.recovery.rollbackingRetryPeriod=1000
server.recovery.timeoutRetryPeriod=1000
server.maxCommitRetryTimeout=-1
server.maxRollbackRetryTimeout=-1
server.rollbackRetryTimeoutUnlockEnable=false
server.distributedLockExpireTime=10000
server.xaerNotaRetryTimeout=60000
server.session.branchAsyncQueueSize=5000
server.session.enableBranchAsyncRemove=false
server.enableParallelRequestHandle=false
#Metrics configuration, only for the server
metrics.enabled=false
metrics.registryType=compact
metrics.exporterList=prometheus
metrics.exporterPrometheusPort=9898

Demo

数据库

日志表参考官方文档！

CREATE TABLE t_order (`id` BIGINT(11) NOT NULL AUTO_INCREMENT PRIMARY KEY,`user_id` BIGINT(11) DEFAULT NULL COMMENT '用户id',`product_id` BIGINT(11) DEFAULT NULL COMMENT '产品id',`count` INT(11) DEFAULT NULL COMMENT '数量',`money` DECIMAL(11,0) DEFAULT NULL COMMENT '金额',`status` INT(1) DEFAULT NULL COMMENT '订单状态：0：创建中；1：已完结' 
) ENGINE=INNODB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8;SELECT * FROM t_order;

CREATE TABLE t_storage (`id` BIGINT(11) NOT NULL AUTO_INCREMENT PRIMARY KEY,`product_id` BIGINT(11) DEFAULT NULL COMMENT '产品id',`total` INT(11) DEFAULT NULL COMMENT '总库存',`used` INT(11) DEFAULT NULL COMMENT '已用库存',`residue` INT(11) DEFAULT NULL COMMENT '剩余库存'
) ENGINE=INNODB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;INSERT INTO seata_storage.t_storage(`id`, `product_id`, `total`, `used`, `residue`)VALUES ('1', '1', '100', '0', '100');SELECT * FROM t_storage;

CREATE TABLE t_account (`id` BIGINT(11) NOT NULL AUTO_INCREMENT PRIMARY KEY COMMENT 'id',`user_id` BIGINT(11) DEFAULT NULL COMMENT '用户id',`total` DECIMAL(10,0) DEFAULT NULL COMMENT '总额度',`used` DECIMAL(10,0) DEFAULT NULL COMMENT '已用余额',`residue` DECIMAL(10,0) DEFAULT '0' COMMENT '剩余可用额度'
) ENGINE=INNODB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;INSERT INTO seata_account.t_account(`id`, `user_id`, `total`, `used`, `residue`)  VALUES ('1', '1', '1000', '0', '1000');SELECT * FROM t_account;

版本：nacos2.1.2 + seata1.6.0

seata-order-service2001

依赖

<dependencies><!--nacos--><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId></dependency><!--seata--><dependency><groupId>io.seata</groupId><artifactId>seata-spring-boot-starter</artifactId><version>1.6.0</version></dependency><dependency><groupId>io.seata</groupId><artifactId>seata-all</artifactId><version>1.6.0</version></dependency><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-seata</artifactId><exclusions><exclusion><groupId>io.seata</groupId><artifactId>seata-spring-boot-starter</artifactId></exclusion><exclusion><groupId>io.seata</groupId><artifactId>seata-all</artifactId></exclusion></exclusions></dependency><!--feign--><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-openfeign</artifactId></dependency><!--web-actuator--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-actuator</artifactId></dependency><!--mysql-druid--><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>5.1.37</version></dependency><dependency><groupId>com.alibaba</groupId><artifactId>druid-spring-boot-starter</artifactId><version>1.1.10</version></dependency><dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>2.0.0</version></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency>
</dependencies>

配置

server:port: 2001spring:application:name: seata-order-servicecloud:nacos:discovery:server-addr: localhost:8848alibaba:seata:tx-service-group: mygroupdatasource:driver-class-name: com.mysql.jdbc.Driverurl: jdbc:mysql://localhost:3306/seata_orderusername: rootpassword: 123456seata:service:vgroup-mapping:mygroup: default # key是事务分组名称 value要和服务端的机房名称保持一致config:nacos:data-id: seataServer.properties # 这是默认值group: DEFAULT_GROUP # 这是默认值enabled: trueenable-auto-data-source-proxy: trueapplication-id: ${spring.application.name}feign:hystrix:enabled: falselogging:level:io:seata: infomybatis:mapperLocations: classpath:mapper/*.xml

主启动类

@EnableDiscoveryClient
@EnableFeignClients
@SpringBootApplication
@MapperScan({"com.ramelon.springcloud.dao"})
public class SeataOrderMainApp2001 {public static void main(String[] args) {SpringApplication.run(SeataOrderMainApp2001.class,args);}
}

业务层

@FeignClient(value = "seata-account-service")
public interface AccountService {/* 扣减账户余额*/@PostMapping("/account/decrease")CommonResult decrease(@RequestParam("userId") Long userId, @RequestParam("money") BigDecimal money);
}

public interface OrderService {/* 创建订单*/void create(Order order);
}

@FeignClient(value = "seata-storage-service")
public interface StorageService {/* 扣减库存*/@PostMapping(value = "/storage/decrease")CommonResult decrease(@RequestParam("productId") Long productId, @RequestParam("count") Integer count);
}

@Service
@Slf4j
public class OrderServiceImpl implements OrderService {@Resourceprivate OrderDao orderDao;@Resourceprivate StorageService storageService;@Resourceprivate AccountService accountService;/* 创建订单->调用库存服务扣减库存->调用账户服务扣减账户余额->修改订单状态* 简单说：* 下订单->减库存->减余额->改状态*/@Override@GlobalTransactional(rollbackFor = Exception.class)public void create(Order order) {log.info("------->下单开始");//本应用创建订单orderDao.create(order);//远程调用库存服务扣减库存log.info("------->order-service中扣减库存开始");storageService.decrease(order.getProductId(),order.getCount());log.info("------->order-service中扣减库存结束");//远程调用账户服务扣减余额log.info("------->order-service中扣减余额开始");accountService.decrease(order.getUserId(),order.getMoney());log.info("------->order-service中扣减余额结束");//修改订单状态为已完成log.info("------->order-service中修改订单状态开始");orderDao.update(order.getUserId(),0);log.info("------->order-service中修改订单状态结束");log.info("------->下单结束");}
}

domain

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Order {private Long id;private Long userId;private Long productId;private Integer count;private BigDecimal money;/* 订单状态：0：创建中；1：已完结*/private Integer status;
}

@Data
@AllArgsConstructor
@NoArgsConstructor
public class CommonResult<T> {private Integer code;private String  message;private T       data;public CommonResult(Integer code, String message) {this(code,message,null);}
}

持久层

@Mapper
public interface OrderDao {/* 创建订单*/void create(Order order);/* 修改订单金额*/void update(@Param("userId") Long userId, @Param("status") Integer status);
}

mapper

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" ><mapper namespace="com.ramelon.springcloud.dao.OrderDao"><resultMap id="BaseResultMap" type="com.ramelon.springcloud.domain.Order"><id column="id" property="id" jdbcType="BIGINT"/><result column="user_id" property="userId" jdbcType="BIGINT"/><result column="product_id" property="productId" jdbcType="BIGINT"/><result column="count" property="count" jdbcType="INTEGER"/><result column="money" property="money" jdbcType="DECIMAL"/><result column="status" property="status" jdbcType="INTEGER"/></resultMap><insert id="create">INSERT INTO `t_order` (`id`, `user_id`, `product_id`, `count`, `money`, `status`)VALUES (NULL, #{userId}, #{productId}, #{count}, #{money}, 0);</insert><update id="update">UPDATE `t_order`SET status = 1WHERE user_id = #{userId} AND status = #{status};</update>
</mapper>

控制层

@RestController
public class OrderController {@Autowiredprivate OrderService orderService;/* 创建订单*/@GetMapping("/order/create")public CommonResult create(Order order) {orderService.create(order);return new CommonResult(200, "订单创建成功!");}
}

seata-order-service2002

依赖

<dependencies><!--nacos--><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId></dependency><!--seata--><dependency><groupId>io.seata</groupId><artifactId>seata-spring-boot-starter</artifactId><version>1.6.0</version></dependency><dependency><groupId>io.seata</groupId><artifactId>seata-all</artifactId><version>1.6.0</version></dependency><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-seata</artifactId><exclusions><exclusion><groupId>io.seata</groupId><artifactId>seata-spring-boot-starter</artifactId></exclusion><exclusion><groupId>io.seata</groupId><artifactId>seata-all</artifactId></exclusion></exclusions></dependency><!--feign--><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-openfeign</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>2.0.0</version></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>5.1.37</version></dependency><dependency><groupId>com.alibaba</groupId><artifactId>druid-spring-boot-starter</artifactId><version>1.1.10</version></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency>
</dependencies>

配置

server:port: 2002spring:application:name: seata-storage-servicecloud:nacos:discovery:server-addr: localhost:8848alibaba:seata:tx-service-group: mygroupdatasource:driver-class-name: com.mysql.jdbc.Driverurl: jdbc:mysql://localhost:3306/seata_storageusername: rootpassword: 123456seata:service:vgroup-mapping:mygroup: default # key是事务分组名称 value要和服务端的机房名称保持一致config:nacos:data-id: seataServer.properties # 这是默认值group: DEFAULT_GROUP # 这是默认值enabled: trueenable-auto-data-source-proxy: trueapplication-id: ${spring.application.name}feign:hystrix:enabled: falselogging:level:io:seata: infomybatis:mapperLocations: classpath:mapper/*.xml

主启动类

@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
@MapperScan({"com.ramelon.springcloud.dao"})
public class SeataStorageServiceApplication2002 {public static void main(String[] args) {SpringApplication.run(SeataStorageServiceApplication2002.class,args);}
}

业务层

public interface StorageService {/* 扣减库存*/void decrease(Long productId, Integer count);
}

@Service
public class StorageServiceImpl implements StorageService {private static final Logger LOGGER = LoggerFactory.getLogger(StorageServiceImpl.class);@Resourceprivate StorageDao storageDao;/* 扣减库存*/@Overridepublic void decrease(Long productId, Integer count) {LOGGER.info("------->storage-service中扣减库存开始");storageDao.decrease(productId,count);LOGGER.info("------->storage-service中扣减库存结束");}
}

domain

@Data
public class Storage {private Long id;/* 产品id*/private Long productId;/* 总库存*/private Integer total;/* 已用库存*/private Integer used;/* 剩余库存*/private Integer residue;
}

@Data
@AllArgsConstructor
@NoArgsConstructor
public class CommonResult<T> {private Integer code;private String  message;private T       data;public CommonResult(Integer code, String message){this(code,message,null);}
}

持久层

@Mapper
public interface StorageDao {/* 扣减库存*/void decrease(@Param("productId") Long productId, @Param("count") Integer count);
}

mapper

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" ><mapper namespace="com.ramelon.springcloud.dao.StorageDao"><resultMap id="BaseResultMap" type="com.ramelon.springcloud.domain.Storage"><id column="id" property="id" jdbcType="BIGINT"/><result column="product_id" property="productId" jdbcType="BIGINT"/><result column="total" property="total" jdbcType="INTEGER"/><result column="used" property="used" jdbcType="INTEGER"/><result column="residue" property="residue" jdbcType="INTEGER"/></resultMap><update id="decrease">UPDATE t_storageSET used    = used + #{count},residue = residue - #{count}WHERE product_id = #{productId}</update></mapper>

控制层

@RestController
public class StorageController {@Autowiredprivate StorageService storageService;/* 扣减库存*/@RequestMapping("/storage/decrease")public CommonResult decrease(Long productId, Integer count) {storageService.decrease(productId, count);return new CommonResult(200,"扣减库存成功！");}
}

seata-order-service2003

依赖

<dependencies><!--nacos--><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId></dependency><!--seata--><dependency><groupId>io.seata</groupId><artifactId>seata-spring-boot-starter</artifactId><version>1.6.0</version></dependency><dependency><groupId>io.seata</groupId><artifactId>seata-all</artifactId><version>1.6.0</version></dependency><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-seata</artifactId><exclusions><exclusion><groupId>io.seata</groupId><artifactId>seata-spring-boot-starter</artifactId></exclusion><exclusion><groupId>io.seata</groupId><artifactId>seata-all</artifactId></exclusion></exclusions></dependency><!--feign--><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-openfeign</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>2.0.0</version></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>5.1.37</version></dependency><dependency><groupId>com.alibaba</groupId><artifactId>druid-spring-boot-starter</artifactId><version>1.1.10</version></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency>
</dependencies>

配置

server:port: 2003spring:application:name: seata-account-servicecloud:nacos:discovery:server-addr: localhost:8848alibaba:seata:tx-service-group: mygroupdatasource:driver-class-name: com.mysql.jdbc.Driverurl: jdbc:mysql://localhost:3306/seata_accountusername: rootpassword: 123456seata:service:vgroup-mapping:mygroup: default # key是事务分组名称 value要和服务端的机房名称保持一致config:nacos:data-id: seataServer.properties # 这是默认值group: DEFAULT_GROUP # 这是默认值enabled: trueenable-auto-data-source-proxy: trueapplication-id: ${spring.application.name}feign:hystrix:enabled: falselogging:level:io:seata: infomybatis:mapperLocations: classpath:mapper/*.xml

主启动类

@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
@MapperScan({"com.ramelon.springcloud.dao"})
public class SeataAccountMainApp2003 {public static void main(String[] args) {SpringApplication.run(SeataAccountMainApp2003.class, args);}
}

业务层

public interface AccountService {/* 扣减账户余额* @param userId 用户id* @param money 金额*/void decrease(@RequestParam("userId") Long userId, @RequestParam("money") BigDecimal money);
}

@Service
public class AccountServiceImpl implements AccountService {private static final Logger LOGGER = LoggerFactory.getLogger(AccountServiceImpl.class);@ResourceAccountDao accountDao;/* 扣减账户余额*/@Overridepublic void decrease(Long userId, BigDecimal money) {LOGGER.info("------->account-service中扣减账户余额开始");//模拟超时异常，全局事务回滚//暂停几秒钟线程try { TimeUnit.SECONDS.sleep(5); } catch (InterruptedException e) { e.printStackTrace(); }accountDao.decrease(userId,money);LOGGER.info("------->account-service中扣减账户余额结束");}
}

domain

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Account {private Long id;/* 用户id*/private Long userId;/* 总额度*/private BigDecimal total;/* 已用额度*/private BigDecimal used;/* 剩余额度*/private BigDecimal residue;
}

@Data
@AllArgsConstructor
@NoArgsConstructor
public class CommonResult<T> {private Integer code;private String  message;private T       data;public CommonResult(Integer code, String message) {this(code,message,null);}
}

持久层

@Mapper
public interface AccountDao {/* 扣减账户余额*/void decrease(@Param("userId") Long userId, @Param("money") BigDecimal money);
}

mapper

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" ><mapper namespace="com.ramelon.springcloud.dao.AccountDao"><resultMap id="BaseResultMap" type="com.ramelon.springcloud.domain.Account"><id column="id" property="id" jdbcType="BIGINT"/><result column="user_id" property="userId" jdbcType="BIGINT"/><result column="total" property="total" jdbcType="DECIMAL"/><result column="used" property="used" jdbcType="DECIMAL"/><result column="residue" property="residue" jdbcType="DECIMAL"/></resultMap><update id="decrease">UPDATE t_accountSETresidue = residue - #{money},used = used + #{money}WHEREuser_id = #{userId};</update></mapper>

控制层

@RestController
public class AccountController {@ResourceAccountService accountService;/* 扣减账户余额*/@RequestMapping("/account/decrease")public CommonResult decrease(@RequestParam("userId") Long userId, @RequestParam("money") BigDecimal money){accountService.decrease(userId,money);return new CommonResult(200,"扣减账户余额成功！");}
}

结果

下图是消费成功截图，数据库也会有对应的纪录。

在AccountServiceImpl增加延迟。feign会超时。但是数据库会有对应的纪录。正确的结果不应该有记录。应该全部回滚。

下面在2001业务层加上@GlobalTransactional(rollbackFor = Exception.class)开启分布式事务

此时看到失败，但是数据库不会有数据，已经回滚了！！！

如下是回滚日志，详细说明参考官方文档，如果想看日志，就打断点，事物结束后，日志表记录会被删完。

{"branchId": 641789253,"undoItems": [{"afterImage": {"rows": [{"fields": [{"name": "id","type": 4,"value": 1}, {"name": "name","type": 12,"value": "GTS"}, {"name": "since","type": 12,"value": "2014"}]}],"tableName": "product"},"beforeImage": {"rows": [{"fields": [{"name": "id","type": 4,"value": 1}, {"name": "name","type": 12,"value": "TXC"}, {"name": "since","type": 12,"value": "2014"}]}],"tableName": "product"},"sqlType": "UPDATE"}],"xid": "xid:xxx"
}

流程说明