一、分布式事务问题由来

分布式前

单机单库没这个问题
从1:1 -> 1:N -> N:N
单体应用被拆分成微服务应用，原来的三个模块被拆分成三个独立的应用,分别使用三个独立的数据源，业务操作需要调用三三 个服务来完成。此时每个服务内部的数据一致性由本地事务来保证， 但是全局的数据一致性问题没法保证。

一句话：一次业务操作需要跨多个数据源或需要跨多个系统进行远程调用，就会产生分布式事务问题。

二、Seata简介

1、是什么

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。
官方网址

2、能干嘛

一个典型的分布式事务过程
分布式事务处理过程的一ID+三组件模型：

• Transaction ID XID 全局唯一的事务ID
• 三组件概念
  • 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。

处理过程：

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。

三、Seata-Server安装

1、去哪下

发布说明: https://github.com/seata/seata/releases

2、怎么玩

本地@Transactional
全局@GlobalTransactional

3、SEATA 的分布式交易解决方案

我们只需要使用一个 @GlobalTransactional 注解在业务方法上。

4、Seata-Server安装

官网地址 - http://seata.io/zh-cn/
下载版本 - 0.9.0
seata-server-0.9.0.zip解压到指定目录并修改conf目录下的file.conf配置文件
先备份原始file.conf文件
主要修改:自定义事务组名称+事务日志存储模式为db +数据库连接信息
file.conf
service模块

service {
    ##fsp_tx_group是自定义的
    vgroup_mapping.my.test.tx_group="fsp_tx_group" 
    default.grouplist = "127.0.0.1:8091"
    enableDegrade = false
    disable = false
    max.commitretry.timeout= "-1"
    max.ollbackretry.timeout= "-1"
}

store模块

## transaction log store
store {
    ## store mode: file, db
    ## 改成db
    mode = "db"
    ## file store
    file {
        dir = "sessionStore"
        # branch session size, if exceeded first try compress lockkey, still exceeded throws exceptions
        max-branch-session-size = 16384
        # globe session size, if exceeded throws exceptions
        max-global-session-size = 512
        # file buffer size, if exceeded allocate new buffer
        file-write-buffer-cache-size = 16384
        # when recover batch read size
        session.reload.read_size= 100
        # async, sync
        flush-disk-mode = async
    }
    # database store
    db {
        ## the implement of javax.sql.DataSource, such as DruidDataSource(druid)/BasicDataSource(dbcp) etc.
        datasource = "dbcp"
        ## mysql/oracle/h2/oceanbase etc.
        ## 配置数据源
        db-type = "mysql"
        driver-class-name = "com.mysql.jdbc.Driver"
        url = "jdbc:mysql://127.0.0.1:3306/seata"
        user = "root"
        password = "你自己密码"
        min-conn= 1
        max-conn = 3
        global.table = "global_table"
        branch.table = "branch_table"
        lock-table = "lock_table"
        query-limit = 100
    }
}

mysql5.7数据库新建库seata，在seata库里建表
建表db_store.sql在\seata-server-0.9.0\seata\conf目录里面

-- the table to store GlobalSession data
drop table if exists `global_table`;
create table `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_gmt_modified_status` (`gmt_modified`, `status`),
  key `idx_transaction_id` (`transaction_id`)
);
-- the table to store BranchSession data
drop table if exists `branch_table`;
create table `branch_table` (
  `branch_id` bigint not null,
  `xid` varchar(128) not null,
  `transaction_id` bigint ,
  `resource_group_id` varchar(32),
  `resource_id` varchar(256) ,
  `lock_key` varchar(128) ,
  `branch_type` varchar(8) ,
  `status` tinyint,
  `client_id` varchar(64),
  `application_data` varchar(2000),
  `gmt_create` datetime,
  `gmt_modified` datetime,
  primary key (`branch_id`),
  key `idx_xid` (`xid`)
);
-- the table to store lock data
drop table if exists `lock_table`;
create table `lock_table` (
  `row_key` varchar(128) not null,
  `xid` varchar(96),
  `transaction_id` long ,
  `branch_id` long,
  `resource_id` varchar(256) ,
  `table_name` varchar(32) ,
  `pk` varchar(36) ,
  `gmt_create` datetime ,
  `gmt_modified` datetime,
  primary key(`row_key`)
);

修改seata-server-0.9.0\seata\conf目录下的registry.conf配置文件

registry {
  # file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
  # 改用为nacos
  type = "nacos"
  nacos {
      ## 加端口号
    serverAddr = "localhost:8848"
    namespace = ""
    cluster = "default"
  }
  ...
}

目的是：指明注册中心为nacos，及修改nacos连接信息
先启动Nacos端口号8848 nacos\bin\startup.cmd
再启动seata-server - seata-server-0.9.0\seata\bin\seata-server.bat

四、Seata业务数据库准备

以下演示都需要先启动Nacos后启动Seata,保证两个都OK。
分布式事务业务说明
这里我们会创建三个服务，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。
一言蔽之，下订单—>扣库存—>减账户(余额)。

1、创建业务数据库

• 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。

建库SQL

CREATE DATABASE seata_order;
CREATE DATABASE seata_storage;
CREATE DATABASE seata_account;

2、按照上述3库分别建对应业务表

• seata_order库下建t_order表

  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'
  );
  SELECT * FROM t_order;

• seata_storage库下建t_storage表 ``sql CREATE TABLE t_storage (idBIGINT(11) NOT NULL AUTO_INCREMENT PRIMARY KEY,product_idBIGINT(11) DEFAULT NULL COMMENT '产品id',totalINT(11) DEFAULT NULL COMMENT '总库存',usedINT(11) DEFAULT NULL COMMENT '已用库存',residue` INT(11) DEFAULT NULL COMMENT ‘剩余库存’ );

INSERT INTO seata_storage.t_storage(id, product_id, total, used, residue) VALUES (‘1’, ‘1’, ‘100’, ‘0’,’100’);

SELECT * FROM t_storage;

- seata_account库下建t_account表
```sql
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'
);
INSERT INTO seata_account.t_account(`id`, `user_id`, `total`, `used`, `residue`)
VALUES ('1', '1', '1000', '0', '1000');
SELECT * FROM t_account;

3、按照上述3库分别建对应的回滚日志表

• 订单-库存-账户3个库下都需要建各自的回滚日志表
• \seata-server-0.9.0\seata\conf目录下的db undo log.sql
• 建表SQL

  -- the table to store seata xid data
  -- 0.7.0+ add context
  -- you must to init this sql for you business databese. the seata server not need it.
  -- 此脚本必须初始化在你当前的业务数据库中，用于AT 模式XID记录。与server端无关（注：业务数据库）
  -- 注意此处0.3.0+ 增加唯一索引 ux_undo_log
  drop table `undo_log`;
  CREATE TABLE `undo_log` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  `branch_id` bigint(20) NOT NULL,
  `xid` varchar(100) NOT NULL,
  `context` varchar(128) NOT NULL,
  `rollback_info` longblob NOT NULL,
  `log_status` int(11) NOT NULL,
  `log_created` datetime NOT NULL,
  `log_modified` datetime NOT NULL,
  `ext` varchar(100) DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `ux_undo_log` (`xid`,`branch_id`)
  ) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

五、订单/库存/账户业务微服务准备

下订单 -> 减库存 -> 扣余额 -> 改（订单）状态

1、Seata之Order-Module

seata-order-service2001
POM

 <dependencies>
   <!--nacos-->
   <dependency>
     <groupId>com.alibaba.cloud</groupId>
     <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
   </dependency>
   <!--seata-->
   <dependency>
     <groupId>com.alibaba.cloud</groupId>
     <artifactId>spring-cloud-starter-alibaba-seata</artifactId>
     <exclusions>
       <exclusion>
         <artifactId>seata-all</artifactId>
         <groupId>io.seata</groupId>
       </exclusion>
     </exclusions>
   </dependency>
   <dependency>
     <groupId>io.seata</groupId>
     <artifactId>seata-all</artifactId>
     <version>0.9.0</version>
   </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>

YML

server:
  port: 2001
spring:
  application:
    name: seata-order-service
  cloud:
    alibaba:
      seata:
        #自定义事务组名称需要与seata-server中的对应
        tx-service-group: fsp_tx_group
    nacos:
      discovery:
        server-addr: localhost:8848
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/seata_order
    username: root
    password: 123456
feign:
  hystrix:
    enabled: false
logging:
  level:
    io:
      seata: info
mybatis:
  mapperLocations: classpath:mapper/*.xml

在resouces下添加配置文件file.conf、registry.conf
file.conf

transport {
  # tcp udt unix-domain-socket
  type = "TCP"
  #NIO NATIVE
  server = "NIO"
  #enable heartbeat
  heartbeat = true
  #thread factory for netty
  thread-factory {
    boss-thread-prefix = "NettyBoss"
    worker-thread-prefix = "NettyServerNIOWorker"
    server-executor-thread-prefix = "NettyServerBizHandler"
    share-boss-worker = false
    client-selector-thread-prefix = "NettyClientSelector"
    client-selector-thread-size = 1
    client-worker-thread-prefix = "NettyClientWorkerThread"
    # netty boss thread size,will not be used for UDT
    boss-thread-size = 1
    #auto default pin or 8
    worker-thread-size = 8
  }
  shutdown {
    # when destroy server, wait seconds
    wait = 3
  }
  serialization = "seata"
  compressor = "none"
}
service {
  vgroup_mapping.fsp_tx_group = "default" #修改自定义事务组名称
  default.grouplist = "127.0.0.1:8091"
  enableDegrade = false
  disable = false
  max.commit.retry.timeout = "-1"
  max.rollback.retry.timeout = "-1"
  disableGlobalTransaction = false
}
client {
  async.commit.buffer.limit = 10000
  lock {
    retry.internal = 10
    retry.times = 30
  }
  report.retry.count = 5
  tm.commit.retry.count = 1
  tm.rollback.retry.count = 1
}
## transaction log store
store {
  ## store mode: file、db
  mode = "db"
  ## file store
  file {
    dir = "sessionStore"
    # branch session size , if exceeded first try compress lockkey, still exceeded throws exceptions
    max-branch-session-size = 16384
    # globe session size , if exceeded throws exceptions
    max-global-session-size = 512
    # file buffer size , if exceeded allocate new buffer
    file-write-buffer-cache-size = 16384
    # when recover batch read size
    session.reload.read_size = 100
    # async, sync
    flush-disk-mode = async
  }
  ## database store
  db {
    ## the implement of javax.sql.DataSource, such as DruidDataSource(druid)/BasicDataSource(dbcp) etc.
    datasource = "dbcp"
    ## mysql/oracle/h2/oceanbase etc.
    db-type = "mysql"
    driver-class-name = "com.mysql.jdbc.Driver"
    url = "jdbc:mysql://127.0.0.1:3306/seata"
    user = "root"
    password = "123456"
    min-conn = 1
    max-conn = 3
    global.table = "global_table"
    branch.table = "branch_table"
    lock-table = "lock_table"
    query-limit = 100
  }
}
lock {
  ## the lock store mode: local、remote
  mode = "remote"
  local {
    ## store locks in user's database
  }
  remote {
    ## store locks in the seata's server
  }
}
recovery {
  #schedule committing retry period in milliseconds
  committing-retry-period = 1000
  #schedule asyn committing retry period in milliseconds
  asyn-committing-retry-period = 1000
  #schedule rollbacking retry period in milliseconds
  rollbacking-retry-period = 1000
  #schedule timeout retry period in milliseconds
  timeout-retry-period = 1000
}
transaction {
  undo.data.validation = true
  undo.log.serialization = "jackson"
  undo.log.save.days = 7
  #schedule delete expired undo_log in milliseconds
  undo.log.delete.period = 86400000
  undo.log.table = "undo_log"
}
## metrics settings
metrics {
  enabled = false
  registry-type = "compact"
  # multi exporters use comma divided
  exporter-list = "prometheus"
  exporter-prometheus-port = 9898
}
support {
  ## spring
  spring {
    # auto proxy the DataSource bean
    datasource.autoproxy = false
  }
}

registry.conf

registry {
  # file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
  type = "nacos"
  nacos {
    serverAddr = "localhost:8848"
    namespace = ""
    cluster = "default"
  }
  eureka {
    serviceUrl = "http://localhost:8761/eureka"
    application = "default"
    weight = "1"
  }
  redis {
    serverAddr = "localhost:6379"
    db = "0"
  }
  zk {
    cluster = "default"
    serverAddr = "127.0.0.1:2181"
    session.timeout = 6000
    connect.timeout = 2000
  }
  consul {
    cluster = "default"
    serverAddr = "127.0.0.1:8500"
  }
  etcd3 {
    cluster = "default"
    serverAddr = "http://localhost:2379"
  }
  sofa {
    serverAddr = "127.0.0.1:9603"
    application = "default"
    region = "DEFAULT_ZONE"
    datacenter = "DefaultDataCenter"
    cluster = "default"
    group = "SEATA_GROUP"
    addressWaitTime = "3000"
  }
  file {
    name = "file.conf"
  }
}
config {
  # file、nacos 、apollo、zk、consul、etcd3
  type = "file"
  nacos {
    serverAddr = "localhost"
    namespace = ""
  }
  consul {
    serverAddr = "127.0.0.1:8500"
  }
  apollo {
    app.id = "seata-server"
    apollo.meta = "http://192.168.1.204:8801"
  }
  zk {
    serverAddr = "127.0.0.1:2181"
    session.timeout = 6000
    connect.timeout = 2000
  }
  etcd3 {
    serverAddr = "http://localhost:2379"
  }
  file {
    name = "file.conf"
  }
}

domain

@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);
    }
}

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

Dao接口及实现

@Mapper
public interface  
{
    //1 新建订单
    void create(Order order);
    //2 修改订单状态，从零改为1
    void update(@Param("userId") Long userId,@Param("status") Integer status);
}

resources文件夹下新建mapper文件夹后添加OrderMapper.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.springcloud.alibaba.dao.OrderDao">
    <resultMap id="BaseResultMap" type="com.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 = 1
        where user_id=#{userId} and status = #{status};
    </update>
</mapper>

Service接口及实现

1. OrderService

   public interface OrderService {
    void create(Order order);
   }

2. OrderServiceImpl

   @Service
   @Slf4j
   public class OrderServiceImpl implements OrderService
   {
    @Resource
    private OrderDao orderDao;
    @Resource
    private StorageService storageService;
    @Resource
    private 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->扣库存->减余额->改状态
     */
    @Override
    //@GlobalTransactional(name = "fsp-create-order",rollbackFor = Exception.class)
    public void create(Order order)
    {
        log.info("----->开始新建订单");
        //1 新建订单
        orderDao.create(order);
        //2 扣减库存
        log.info("----->订单微服务开始调用库存，做扣减Count");
        storageService.decrease(order.getProductId(),order.getCount());
        log.info("----->订单微服务开始调用库存，做扣减end");
        //3 扣减账户
        log.info("----->订单微服务开始调用账户，做扣减Money");
        accountService.decrease(order.getUserId(),order.getMoney());
        log.info("----->订单微服务开始调用账户，做扣减end");
        //4 修改订单状态，从零到1,1代表已经完成
        log.info("----->修改订单状态开始");
        orderDao.update(order.getUserId(),0);
        log.info("----->修改订单状态结束");
        log.info("----->下订单结束了，O(∩_∩)O哈哈~");
    }
   }

3. StorageService

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

4. AccountService

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

   Controller ```java @RestController public class OrderController { @Resource private OrderService orderService;

@GetMapping("/order/create")
public CommonResult create(Order order)
{
    orderService.create(order);
    return new CommonResult(200,"订单创建成功");
}

}

Config配置
1. MyBatisConfig
```java
@Configuration
@MapperScan({"com.springcloud.dao"})
public class MyBatisConfig {
}

1. DataSourceProxyConfig ```java /**

   • 使用Seata对数据源进行代理 */ @Configuration public class DataSourceProxyConfig {

     @Value(“${mybatis.mapperLocations}”) private String mapperLocations;

     @Bean @ConfigurationProperties(prefix = “spring.datasource”) public DataSource druidDataSource(){ return new DruidDataSource(); }

     @Bean public DataSourceProxy dataSourceProxy(DataSource dataSource) { return new DataSourceProxy(dataSource); }

     @Bean public SqlSessionFactory sqlSessionFactoryBean(DataSourceProxy dataSourceProxy) throws Exception { SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean(); sqlSessionFactoryBean.setDataSource(dataSourceProxy); sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources(mapperLocations)); sqlSessionFactoryBean.setTransactionFactory(new SpringManagedTransactionFactory()); return sqlSessionFactoryBean.getObject(); }

}

主启动
```java
@EnableDiscoveryClient
@EnableFeignClients
//取消数据源的自动创建，而是使用自己定义的
@SpringBootApplication(exclude = DataSourceAutoConfiguration.class)
public class SeataOrderMainApp2001
{
    public static void main(String[] args)
    {
        SpringApplication.run(SeataOrderMainApp2001.class, args);
    }
}

2、Seata之Storage-Module

与seata-order-service2001模块大致相同
seata- storage - service2002
POM（与seata-order-service2001模块大致相同）
YML

server:
  port: 2002
spring:
  application:
    name: seata-storage-service
  cloud:
    alibaba:
      seata:
        tx-service-group: fsp_tx_group
    nacos:
      discovery:
        server-addr: localhost:8848
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/seata_storage
    username: root
    password: 123456
logging:
  level:
    io:
      seata: info
mybatis:
  mapperLocations: classpath:mapper/*.xml

file.conf（与seata-order-service2001模块大致相同）
registry.conf（与seata-order-service2001模块大致相同）
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;
}

CommonResult（与seata-order-service2001模块大致相同）
Dao接口及实现

1. StorageDao

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

2. resources文件夹下新建mapper文件夹后添加StorageMapper.xml ```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“ >

<resultMap id="BaseResultMap" type="com.springcloud.alibaba.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_storage
    SET
        used = used + #{count},residue = residue - #{count}
    WHERE
        product_id = #{productId}
</update>

Service接口及实现
1. StorageService
```java
public interface StorageService {
    /**
     * 扣减库存
     */
    void decrease(Long productId, Integer count);
}

server:
  port: 2003
spring:
  application:
    name: seata-account-service
  cloud:
    alibaba:
      seata:
        tx-service-group: fsp_tx_group
    nacos:
      discovery:
        server-addr: localhost:8848
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/seata_account
    username: root
    password: 123456
feign:
  hystrix:
    enabled: false
logging:
  level:
    io:
      seata: info
mybatis:
  mapperLocations: classpath:mapper/*.xml

@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;
}

<resultMap id="BaseResultMap" type="com.springcloud.alibaba.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_account
    SET
      residue = residue - #{money},used = used + #{money}
    WHERE
      user_id = #{userId};
</update>

Service接口及实现
1. AccountService
```java
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);
}

@Resource
AccountDao accountDao;
/**
 * 扣减账户余额
 */
@Override
public void decrease(Long userId, BigDecimal money) {
    LOGGER.info("------->account-service中扣减账户余额开始");
    accountDao.decrease(userId,money);
    LOGGER.info("------->account-service中扣减账户余额结束");
}

Controller
```java
@RestController
public class AccountController {
    @Resource
    AccountService 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！");
    }
}

SELECT * FROM seata_account.t_account;
SELECT * FROM seata_order.t_order;
SELECT * FROM seata_storage.t_storage;

@Service
public class AccountServiceImpl implements AccountService {
    private static final Logger LOGGER = LoggerFactory.getLogger(AccountServiceImpl.class);
    @Resource
    AccountDao accountDao;
    /**
     * 扣减账户余额
     */
    @Override
    public 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(20);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        accountDao.decrease(userId,money);
        LOGGER.info("------->account-service中扣减账户余额结束");
    }
}

@Service
@Slf4j
public class OrderServiceImpl implements OrderService {
    ...
    /**
     * 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->扣库存->减余额->改状态
     */
    @Override
    //rollbackFor = Exception.class表示对任意异常都进行回滚
    @GlobalTransactional(name = "fsp-create-order",rollbackFor = Exception.class)
    public void create(Order order)
    {
        ...
    }
}