SpringCloud Alibaba之Seata处理分布式事务

（学习笔记，必用必考）

问题：@Transactional 的9种失效场景？

1、介绍

1.1、简介

官网地址：Apache Seata

源码地址：Releases · apache/incubator-seata · GitHub

Seata是一款开源的分布式事务解决方案，致力于在微服务架构下提供高性能和简单易用的分布式事务服务。

1.2、Seata的工作流程

Seata的工作流程：纵观整个分布式事务的管理，就是全局事务ID的传递和变更，要让开发者无感知

（1）Seata对分布式事务的协调和控制，就是1+3

1个XID：XID是全局事务的唯一标识，它可以在服务的调用链路中传递，绑定到服务的事务上下文中。

3个概念（TC、TM、RM）：

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。

TC→TM→RM

TC：就是Seata，负责维护全局事务和分支事务的状态，驱动全局事务提交或回滚。

TM：标注全局@GlobalTransactional启动入口动作的微服务模块 (比如订单模块)，它是事务的发起者，负责定义全局事务的范围，并根据TC 维护的全局事务和分支事务状态，做出开始事务、提交事务、回滚事务的决议

RM：就是mysql数据库本身，可以是多个RM，负责管理分支事务上的资源，向TC注册分支事务，汇报分支事务状态，驱动分支事务的提交或回滚

（2）总结：

1、TM 向 TC 申请开启一个全局事务，全局事务创建成功并生成一个全局唯一的 XID；
2、XID 在微服务调用链路的上下文中传播；
3、RM 向 TC 注册分支事务，将其纳入 XID 对应全局事务的管辖；
4、TM 向 TC 发起针对 XID 的全局提交或回滚决议；
5、TC 调度 XID 下管辖的全部分支事务完成提交或回滚请求。

（3）Seata模式

2、下载安装

下载地址：Seata Java Download | Apache Seata

下载版本：Release v2.0.0(Not Apache release) · apache/incubator-seata · GitHub

Seata参数官网参考：参数配置 | Apache Seata

2.1、mysql数据库建库建表

CREATE DATABASE seata;

USE seata;

建表地址：incubator-seata/script/server/db/mysql.sql at develop · apache/incubator-seata · GitHub

-- -------------------------------- The script used when storeMode is 'db' --------------------------------
-- the table to store GlobalSession data
CREATE TABLE IF NOT EXISTS `global_table`
(
    `xid`                       VARCHAR(128) NOT NULL,
    `transaction_id`            BIGINT,
    `status`                    TINYINT      NOT NULL,
    `application_id`            VARCHAR(32),
    `transaction_service_group` VARCHAR(32),
    `transaction_name`          VARCHAR(128),
    `timeout`                   INT,
    `begin_time`                BIGINT,
    `application_data`          VARCHAR(2000),
    `gmt_create`                DATETIME,
    `gmt_modified`              DATETIME,
    PRIMARY KEY (`xid`),
    KEY `idx_status_gmt_modified` (`status` , `gmt_modified`),
    KEY `idx_transaction_id` (`transaction_id`)
) ENGINE = InnoDB
  DEFAULT CHARSET = utf8mb4;

-- the table to store BranchSession data
CREATE TABLE IF NOT EXISTS `branch_table`
(
    `branch_id`         BIGINT       NOT NULL,
    `xid`               VARCHAR(128) NOT NULL,
    `transaction_id`    BIGINT,
    `resource_group_id` VARCHAR(32),
    `resource_id`       VARCHAR(256),
    `branch_type`       VARCHAR(8),
    `status`            TINYINT,
    `client_id`         VARCHAR(64),
    `application_data`  VARCHAR(2000),
    `gmt_create`        DATETIME(6),
    `gmt_modified`      DATETIME(6),
    PRIMARY KEY (`branch_id`),
    KEY `idx_xid` (`xid`)
) ENGINE = InnoDB
  DEFAULT CHARSET = utf8mb4;

-- the table to store lock data
CREATE TABLE IF NOT EXISTS `lock_table`
(
    `row_key`        VARCHAR(128) NOT NULL,
    `xid`            VARCHAR(128),
    `transaction_id` BIGINT,
    `branch_id`      BIGINT       NOT NULL,
    `resource_id`    VARCHAR(256),
    `table_name`     VARCHAR(32),
    `pk`             VARCHAR(36),
    `status`         TINYINT      NOT NULL DEFAULT '0' COMMENT '0:locked ,1:rollbacking',
    `gmt_create`     DATETIME,
    `gmt_modified`   DATETIME,
    PRIMARY KEY (`row_key`),
    KEY `idx_status` (`status`),
    KEY `idx_branch_id` (`branch_id`),
    KEY `idx_xid` (`xid`)
) ENGINE = InnoDB
  DEFAULT CHARSET = utf8mb4;

CREATE TABLE IF NOT EXISTS `distributed_lock`
(
    `lock_key`       CHAR(20) NOT NULL,
    `lock_value`     VARCHAR(20) NOT NULL,
    `expire`         BIGINT,
    primary key (`lock_key`)
) ENGINE = InnoDB
  DEFAULT CHARSET = utf8mb4;

INSERT INTO `distributed_lock` (lock_key, lock_value, expire) VALUES ('AsyncCommitting', ' ', 0);
INSERT INTO `distributed_lock` (lock_key, lock_value, expire) VALUES ('RetryCommitting', ' ', 0);
INSERT INTO `distributed_lock` (lock_key, lock_value, expire) VALUES ('RetryRollbacking', ' ', 0);
INSERT INTO `distributed_lock` (lock_key, lock_value, expire) VALUES ('TxTimeoutCheck', ' ', 0);

2.2、Seata配置

修改seata-server-2.0.0\conf\application.yml配置文件（改之前先备份）

改好的配置：

#  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: 7091
 
spring:
  application:
    name: seata-server
 
logging:
  config: classpath:logback-spring.xml
  file:
    path: ${log.home:${user.home}/logs/seata}
  extend:
    logstash-appender:
      destination: 127.0.0.1:4560
    kafka-appender:
      bootstrap-servers: 127.0.0.1:9092
      topic: logback_to_logstash
 
console:
  user:
    username: seata
    password: seata
 
 
seata:
  config:
    type: nacos
    nacos:
      server-addr: 127.0.0.1:8848
      namespace:
      group: SEATA_GROUP #后续自己在nacos里面新建,不想新建SEATA_GROUP，就写DEFAULT_GROUP
      username: nacos
      password: nacos
  registry:
    type: nacos
    nacos:
      application: seata-server
      server-addr: 127.0.0.1:8848
      group: SEATA_GROUP #后续自己在nacos里面新建,不想新建SEATA_GROUP，就写DEFAULT_GROUP
      namespace:
      cluster: default
      username: nacos
      password: nacos    
  store:
    mode: db
    db:
      datasource: druid
      db-type: mysql
      driver-class-name: com.mysql.cj.jdbc.Driver
      url: jdbc:mysql://localhost:3306/seata?characterEncoding=utf8&useSSL=false&serverTimezone=GMT%2B8&rewriteBatchedStatements=true&allowPublicKeyRetrieval=true
      user: root
      password: 123456
      min-conn: 10
      max-conn: 100
      global-table: global_table
      branch-table: branch_table
      lock-table: lock_table
      distributed-lock-table: distributed_lock
      query-limit: 1000
      max-wait: 5000
 
 
 
  #  server:
  #    service-port: 8091 #If not configured, the default is '${server.port} + 1000'
  security:
    secretKey: SeataSecretKey0c382ef121d778043159209298fd40bf3850a017
    tokenValidityInMilliseconds: 1800000
    ignore:
      urls: /,/**/*.css,/**/*.js,/**/*.html,/**/*.map,/**/*.svg,/**/*.png,/**/*.jpeg,/**/*.ico,/api/v1/auth/login,/metadata/v1/**

2.3、运行

先启动nacos，再执行seata-server.bat命令

访问地址：http://localhost:7091

账号和密码都是：seata

3、Seata案例实战（AT模式）

3.1、数据库和表准备

3.1.1、案例业务说明

创建三个服务，一个订单服务，一个库存服务，一个账户服务。

当用户下单时，会在订单服务中创建一个订单，然后通过远程调用库存服务来扣减下单商品的库存，

再通过远程调用账户服务来扣减用户账户里面的余额，

最后在订单服务中修改订单状态为已完成。该操作跨越三个数据库，有两次远程调用，很明显会有分布式事务问题。

下订单 → 减库存 → 扣余额 → 改(订单)状态

3.1.2、建库sql

seata_order：存储订单的数据库

seata_storage：存储库存的数据库

seata_account：存储账户信息的数据库

CREATE DATABASE seata_order;
 
CREATE DATABASE seata_storage;

CREATE DATABASE seata_account;

3.1.3、按照上述3库分别建对应的undo_log回滚日志表

订单-库存-账户3个库下都需要建各自的undo_log

官网sql地址：incubator-seata/script/client/at/db/mysql.sql at 2.x · apache/incubator-seata · GitHub

AT模式专用，其它模式不需要

-- for AT mode you must to init this sql for you business database. the seata server not need it.
CREATE TABLE IF NOT EXISTS `undo_log`
(
    `branch_id`     BIGINT       NOT NULL COMMENT 'branch transaction id',
    `xid`           VARCHAR(128) NOT NULL COMMENT 'global transaction id',
    `context`       VARCHAR(128) NOT NULL COMMENT 'undo_log context,such as serialization',
    `rollback_info` LONGBLOB     NOT NULL COMMENT 'rollback info',
    `log_status`    INT(11)      NOT NULL COMMENT '0:normal status,1:defense status',
    `log_created`   DATETIME(6)  NOT NULL COMMENT 'create datetime',
    `log_modified`  DATETIME(6)  NOT NULL COMMENT 'modify datetime',
    UNIQUE KEY `ux_undo_log` (`xid`, `branch_id`)
) ENGINE = InnoDB AUTO_INCREMENT = 1 DEFAULT CHARSET = utf8mb4 COMMENT ='AT transaction mode undo table';
ALTER TABLE `undo_log` ADD INDEX `ix_log_created` (`log_created`);

3.1.4、建表sql

seata_order：存储订单的数据库

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=1 DEFAULT CHARSET=utf8;
SELECT * FROM t_order;

seata_account：存储账户信息的数据库

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 '已用账户余额',
`residue` DECIMAL(10,0) DEFAULT '0' COMMENT '剩余可用额度'
)ENGINE=INNODB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;
INSERT INTO t_account(`id`,`user_id`,`total`,`used`,`residue`)VALUES('1','1','1000','0','1000');
SELECT * FROM t_account;

seata_storage：存储库存的数据库

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=1 DEFAULT CHARSET=utf8;

INSERT INTO t_storage(`id`,`product_id`,`total`,`used`,`residue`)VALUES('1','1','100','0','100');
SELECT * FROM t_storage;

最终数据库：

3.2、微服务编码实现

3.2.1、修改cloud-api-commons

修改cloud-api-commons新增库存和账户两个Feign服务接口

package com.atguigu.cloud.apis;

import com.atguigu.cloud.resp.ResultData;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;

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

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

3.2.2、新建订单Order微服务

（1）新建Module seata-order-service2001

（2）pom

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.atguigu.cloud</groupId>
        <artifactId>springcloud2024</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>

    <artifactId>seata-order-service2001</artifactId>

    <properties>
        <maven.compiler.source>17</maven.compiler.source>
        <maven.compiler.target>17</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <!-- nacos -->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        <!--alibaba-seata-->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-seata</artifactId>
        </dependency>
        <!--openfeign-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <!--loadbalancer-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-loadbalancer</artifactId>
        </dependency>
        <!--cloud-api-commons-->
        <dependency>
            <groupId>com.atguigu.cloud</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>1.0-SNAPSHOT</version>
        </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>
        <!--SpringBoot集成druid连接池-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
        </dependency>
        <!-- Swagger3 调用方式 http://你的主机IP地址:5555/swagger-ui/index.html -->
        <dependency>
            <groupId>org.springdoc</groupId>
            <artifactId>springdoc-openapi-starter-webmvc-ui</artifactId>
        </dependency>
        <!--mybatis和springboot整合-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
        </dependency>
        <!--Mysql数据库驱动8 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <!--persistence-->
        <dependency>
            <groupId>javax.persistence</groupId>
            <artifactId>persistence-api</artifactId>
        </dependency>
        <!--通用Mapper4-->
        <dependency>
            <groupId>tk.mybatis</groupId>
            <artifactId>mapper</artifactId>
        </dependency>
        <!--hutool-->
        <dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
        </dependency>
        <!-- fastjson2 -->
        <dependency>
            <groupId>com.alibaba.fastjson2</groupId>
            <artifactId>fastjson2</artifactId>
        </dependency>
        <!--lombok-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.28</version>
            <scope>provided</scope>
        </dependency>
        <!--test-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

（3）yaml

server:
  port: 2001

spring:
  application:
    name: seata-order-service
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848         #Nacos服务注册中心地址
  # ==========applicationName + druid-mysql8 driver===================
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/seata_order?characterEncoding=utf8&useSSL=false&serverTimezone=GMT%2B8&rewriteBatchedStatements=true&allowPublicKeyRetrieval=true
    username: root
    password: 123456
# ========================mybatis===================
mybatis:
  mapper-locations: classpath:mapper/*.xml
  type-aliases-package: com.atguigu.cloud.entities
  configuration:
    map-underscore-to-camel-case: true

# ========================seata===================
seata:
  registry:
    type: nacos
    nacos:
      server-addr: 127.0.0.1:8848
      namespace: ""
      group: SEATA_GROUP
      application: seata-server
  tx-service-group: default_tx_group # 事务组，由它获得TC服务的集群名称
  service:
    vgroup-mapping: # 点击源码分析
      default_tx_group: default # 事务组与TC服务集群的映射关系
  data-source-proxy-mode: AT

logging:
  level:
    io:
      seata: info

（4）主启动类

@SpringBootApplication
@MapperScan("com.atguigu.cloud.mapper") //import tk.mybatis.spring.annotation.MapperScan;
@EnableDiscoveryClient //服务注册和发现
@EnableFeignClients
public class SeataOrderMainApp2001 {
    public static void main(String[] args) {
        SpringApplication.run(SeataOrderMainApp2001.class, args);
    }
}

（5）业务类

package com.atguigu.cloud.service.impl;

import com.atguigu.cloud.apis.AccountFeignApi;
import com.atguigu.cloud.apis.StorageFeignApi;
import com.atguigu.cloud.entities.Order;
import com.atguigu.cloud.mapper.OrderMapper;
import com.atguigu.cloud.service.OrderService;
import io.seata.core.context.RootContext;
import io.seata.spring.annotation.GlobalTransactional;
import jakarta.annotation.Resource;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Service;
import tk.mybatis.mapper.entity.Example;

@Slf4j
@Service
public class OrderServiceImpl implements OrderService {
    @Resource
    private OrderMapper orderMapper;
    @Resource//订单微服务通过OpenFeign去调用库存微服务
    private StorageFeignApi storageFeignApi;
    @Resource//订单微服务通过OpenFeign去调用账户微服务
    private AccountFeignApi accountFeignApi;


    @Override
    //@GlobalTransactional(name = "zzyy-create-order",rollbackFor = Exception.class) //AT
    public void create(Order order) {
        //xid检查
        String xid = RootContext.getXID();

        //1. 新建订单
        log.info("==================>开始新建订单" + "\t" + "xid_order:" + xid);
        //订单状态status：0：创建中；1：已完结
        order.setStatus(0);
        int result = orderMapper.insertSelective(order);

        //插入订单成功后获得插入mysql的实体对象
        Order orderFromDB = null;
        if (result > 0) {
            orderFromDB = orderMapper.selectOne(order);
            //orderFromDB = orderMapper.selectByPrimaryKey(order.getId());
            log.info("-------> 新建订单成功，orderFromDB info: " + orderFromDB);
            System.out.println();
            //2. 扣减库存
            log.info("-------> 订单微服务开始调用Storage库存，做扣减count");
            storageFeignApi.decrease(orderFromDB.getProductId(), orderFromDB.getCount());
            log.info("-------> 订单微服务结束调用Storage库存，做扣减完成");
            System.out.println();
            //3. 扣减账号余额
            log.info("-------> 订单微服务开始调用Account账号，做扣减money");
            accountFeignApi.decrease(orderFromDB.getUserId(), orderFromDB.getMoney());
            log.info("-------> 订单微服务结束调用Account账号，做扣减完成");
            System.out.println();
            //4. 修改订单状态
            //订单状态status：0：创建中；1：已完结
            log.info("-------> 修改订单状态");
            orderFromDB.setStatus(1);

            Example whereCondition = new Example(Order.class);
            Example.Criteria criteria = whereCondition.createCriteria();
            criteria.andEqualTo("userId", orderFromDB.getUserId());
            criteria.andEqualTo("status", 0);

            int updateResult = orderMapper.updateByExampleSelective(orderFromDB, whereCondition);

            log.info("-------> 修改订单状态完成" + "\t" + updateResult);
            log.info("-------> orderFromDB info: " + orderFromDB);
        }
        System.out.println();
        log.info("==================>结束新建订单" + "\t" + "xid_order:" + xid);
    }
}

（6）controller

@RestController
public class OrderController {

    @Resource
    private OrderService orderService;

    /**
     * 创建订单
     */
    @GetMapping("/order/create")
    public ResultData create(Order order) {
        orderService.create(order);
        return ResultData.success(order);
    }
}

3.2.3、新建库存Storage微服务

（1）新建Module: seata-storage-service2002

（2）pom

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.atguigu.cloud</groupId>
        <artifactId>springcloud2024</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>

    <artifactId>seata-storage-service2002</artifactId>

    <properties>
        <maven.compiler.source>17</maven.compiler.source>
        <maven.compiler.target>17</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
    <dependencies>
        <!-- nacos -->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        <!--alibaba-seata-->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-seata</artifactId>
        </dependency>
        <!--openfeign-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <!--loadbalancer-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-loadbalancer</artifactId>
        </dependency>
        <!--cloud_commons_utils-->
        <dependency>
            <groupId>com.atguigu.cloud</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>1.0-SNAPSHOT</version>
        </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>
        <!--SpringBoot集成druid连接池-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
        </dependency>
        <!-- Swagger3 调用方式 http://你的主机IP地址:5555/swagger-ui/index.html -->
        <dependency>
            <groupId>org.springdoc</groupId>
            <artifactId>springdoc-openapi-starter-webmvc-ui</artifactId>
        </dependency>
        <!--mybatis和springboot整合-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
        </dependency>
        <!--Mysql数据库驱动8 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <!--persistence-->
        <dependency>
            <groupId>javax.persistence</groupId>
            <artifactId>persistence-api</artifactId>
        </dependency>
        <!--通用Mapper4-->
        <dependency>
            <groupId>tk.mybatis</groupId>
            <artifactId>mapper</artifactId>
        </dependency>
        <!--hutool-->
        <dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
        </dependency>
        <!-- fastjson2 -->
        <dependency>
            <groupId>com.alibaba.fastjson2</groupId>
            <artifactId>fastjson2</artifactId>
        </dependency>
        <!--lombok-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.28</version>
            <scope>provided</scope>
        </dependency>
        <!--test-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

（3）yaml

server:
  port: 2002

spring:
  application:
    name: seata-storage-service
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848         #Nacos服务注册中心地址
  # ==========applicationName + druid-mysql8 driver===================
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/seata_storage?characterEncoding=utf8&useSSL=false&serverTimezone=GMT%2B8&rewriteBatchedStatements=true&allowPublicKeyRetrieval=true
    username: root
    password: 123456
# ========================mybatis===================
mybatis:
  mapper-locations: classpath:mapper/*.xml
  type-aliases-package: com.atguigu.cloud.entities
  configuration:
    map-underscore-to-camel-case: true
# ========================seata===================
seata:
  registry:
    type: nacos
    nacos:
      server-addr: 127.0.0.1:8848
      namespace: ""
      group: SEATA_GROUP
      application: seata-server
  tx-service-group: default_tx_group # 事务组，由它获得TC服务的集群名称
  service:
    vgroup-mapping:
      default_tx_group: default # 事务组与TC服务集群的映射关系
  data-source-proxy-mode: AT

logging:
  level:
    io:
      seata: info

（4）主启动

@SpringBootApplication
@MapperScan("com.atguigu.cloud.mapper") //import tk.mybatis.spring.annotation.MapperScan;
@EnableDiscoveryClient //服务注册和发现
@EnableFeignClients
public class SeataStorageMainApp2002 {
    public static void main(String[] args) {
        SpringApplication.run(SeataStorageMainApp2002.class, args);
    }
}

（5）业务类

package com.atguigu.cloud.service.impl;

import com.atguigu.cloud.mapper.StorageMapper;
import com.atguigu.cloud.service.StorageService;
import jakarta.annotation.Resource;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Service;

@Slf4j
@Service
public class StorageServiceImpl implements StorageService {

    @Resource
    private StorageMapper storageMapper;


    @Override
    public void decrease(Long productId, Integer count) {
        log.info("------->storage-service中扣减库存开始");
        storageMapper.decrease(productId,count);
        log.info("------->storage-service中扣减库存结束");
    }
}

mapper.xml

<?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.atguigu.cloud.mapper.StorageMapper">
  <update id="decrease">
    UPDATE
      t_storage
    SET
      used = used + #{count},
      residue = residue - #{count}
    WHERE product_id = #{productId}
  </update>
</mapper>

（6）controller

@RestController
public class StorageController {
    @Resource
    private StorageService storageService;

    /**
     * 扣减库存
     */
    @RequestMapping("/storage/decrease")
    public ResultData decrease(Long productId, Integer count) {

        storageService.decrease(productId, count);
        return ResultData.success("扣减库存成功!");
    }
}

3.2.4、新建账户Account微服务

（1）创建Module：seata-account-service2003

（2）pom

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.atguigu.cloud</groupId>
        <artifactId>springcloud2024</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>

    <artifactId>seata-account-service2003</artifactId>

    <properties>
        <maven.compiler.source>17</maven.compiler.source>
        <maven.compiler.target>17</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <!-- nacos -->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        <!--alibaba-seata-->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-seata</artifactId>
        </dependency>
        <!--openfeign-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <!--loadbalancer-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-loadbalancer</artifactId>
        </dependency>
        <!--cloud_commons_utils-->
        <dependency>
            <groupId>com.atguigu.cloud</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>1.0-SNAPSHOT</version>
        </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>
        <!--SpringBoot集成druid连接池-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
        </dependency>
        <!-- Swagger3 调用方式 http://你的主机IP地址:5555/swagger-ui/index.html -->
        <dependency>
            <groupId>org.springdoc</groupId>
            <artifactId>springdoc-openapi-starter-webmvc-ui</artifactId>
        </dependency>
        <!--mybatis和springboot整合-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
        </dependency>
        <!--Mysql数据库驱动8 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <!--persistence-->
        <dependency>
            <groupId>javax.persistence</groupId>
            <artifactId>persistence-api</artifactId>
        </dependency>
        <!--通用Mapper4-->
        <dependency>
            <groupId>tk.mybatis</groupId>
            <artifactId>mapper</artifactId>
        </dependency>
        <!--hutool-->
        <dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
        </dependency>
        <!-- fastjson2 -->
        <dependency>
            <groupId>com.alibaba.fastjson2</groupId>
            <artifactId>fastjson2</artifactId>
        </dependency>
        <!--lombok-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.28</version>
            <scope>provided</scope>
        </dependency>
        <!--test-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

（3）yaml

server:
  port: 2003

spring:
  application:
    name: seata-account-service
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848         #Nacos服务注册中心地址
  # ==========applicationName + druid-mysql8 driver===================
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/seata_account?characterEncoding=utf8&useSSL=false&serverTimezone=GMT%2B8&rewriteBatchedStatements=true&allowPublicKeyRetrieval=true
    username: root
    password: 123456
# ========================mybatis===================
mybatis:
  mapper-locations: classpath:mapper/*.xml
  type-aliases-package: com.atguigu.cloud.entities
  configuration:
    map-underscore-to-camel-case: true
# ========================seata===================
seata:
  registry:
    type: nacos
    nacos:
      server-addr: 127.0.0.1:8848
      namespace: ""
      group: SEATA_GROUP
      application: seata-server
  tx-service-group: default_tx_group # 事务组，由它获得TC服务的集群名称
  service:
    vgroup-mapping:
      default_tx_group: default # 事务组与TC服务集群的映射关系
  data-source-proxy-mode: AT

logging:
  level:
    io:
      seata: info

（4）主启动

@EnableDiscoveryClient
@EnableFeignClients
@MapperScan("com.atguigu.cloud.mapper") //import tk.mybatis.spring.annotation.MapperScan;
@SpringBootApplication
public class SeataAccountMainApp2003 {
    public static void main(String[] args) {
        SpringApplication.run(SeataAccountMainApp2003.class, args);
    }
}

（5）业务类

package com.atguigu.cloud.service.impl;

import com.atguigu.cloud.mapper.AccountMapper;
import com.atguigu.cloud.service.AccountService;
import jakarta.annotation.Resource;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Service;

import java.util.concurrent.TimeUnit;

@Slf4j
@Service
public class AccountServiceImpl implements AccountService {
    @Resource
    private AccountMapper accountMapper;
    @Override
    public void decrease(Long userId, Long money) {
        log.info("------->account-service中扣减账户余额开始");
        accountMapper.decrease(userId,money);
        //myTimeOut();
        //int age = 10/0;
        log.info("------->account-service中扣减账户余额结束");
    }

    /**
     * 模拟超时异常，全局事务回滚
     */
    private static void myTimeOut()
    {
        try { TimeUnit.SECONDS.sleep(65); } catch (InterruptedException e) { e.printStackTrace(); }
    }
}

mapper.xml代码

<!--
          money   本次消费金额

          t_account数据库表
          total总额度 = 累计已消费金额(used) + 剩余可用额度(residue)
      -->
  <update id="decrease">
    UPDATE
      t_account
    SET
      residue = residue - #{money},used = used + #{money}
    WHERE user_id = #{userId};
  </update>

（6）controller

package com.atguigu.cloud.controller;

import com.atguigu.cloud.resp.ResultData;
import com.atguigu.cloud.service.AccountService;
import jakarta.annotation.Resource;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class AccountController {
    @Resource
    private AccountService accountService;

    /**
     * 扣减账户余额
     */
    @RequestMapping("/account/decrease")
    public ResultData decrease(@RequestParam("userId") Long userId, @RequestParam("money") Long money) {
        accountService.decrease(userId, money);
        return ResultData.success("扣减账户余额成功！");
    }
}

3.3、测试

3.3.1、正常测试

没有在订单模块添加 @GlobalTransactional

1号用户花费100块钱买了10个1号产品：http://localhost:2001/order/create?userId=1&productId=1&count=10&money=100

出现错误：

导致原因：springboot+springcloud版本太高导致和阿里巴巴Seata不兼容

解决方案：总体父工程，boot+cloud降低版本


<spring.boot.version>3.1.7</spring.boot.version>
<spring.cloud.version>2022.0.4</spring.cloud.version>

再次测试：

数据库情况：新增一个订单+2个扣减

3.3.2、超时异常出错测试，没有@GlobalTransactional

当库存和账户金额扣减后，订单状态并没有设置为已经完成，没有从零改为1

3.3.3、超时异常解决，添加@GlobalTransactional

（1）AccountServiceImpl保留超时方法，OrderServiceImpl添加@GlobalTransactional

此时，订单模块就是TM，也是其中一个RM

（2）查看Seata后台：http://localhost:7091/#/login

全局事务ID

全局锁

下单后数据库3个库数据并没有任何改变，被回滚了

3.4、Seata原理小总结和面试题

AT模式如何做到对业务的无侵入（事务尽量不要超过5个，容易出事故，3个一个事务提交，再组合）

（1）一阶段加载

在一阶段，Seata 会拦截“业务 SQL”，

1 解析 SQL 语义，找到“业务 SQL”要更新的业务数据，在业务数据被更新前，将其保存成“before image”，

2 执行“业务 SQL”更新业务数据，在业务数据更新之后，

3 其保存成“after image”，最后生成行锁。

以上操作全部在一个数据库事务内完成，这样保证了一阶段操作的原子性。

（2）二阶段分2种情况

①正常提交

二阶段如是顺利提交的话，

因为“业务 SQL”在一阶段已经提交至数据库，所以Seata框架只需将一阶段保存的快照数据和行锁删掉，完成数据清理即可。

②异常回滚

二阶段回滚：

二阶段如果是回滚的话，Seata 就需要回滚一阶段已经执行的“业务 SQL”，还原业务数据。

回滚方式便是用“before image”还原业务数据；但在还原前要首先要校验脏写，对比“数据库当前业务数据”和 “after image”，

如果两份数据完全一致就说明没有脏写，可以还原业务数据，如果不一致就说明有脏写，出现脏写就需要转人工处理。