Seata处理分布式事务

学习地址：https://www.bilibili.com/video/BV18E411x7eT?p=138

源码分享：https://github.com/mobiwusihuan288/SpringCloud2020

分布式事务问题

分布式前

单机单库没这个问题

从1：1 -> 1:N -> N: N

分布式之后

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。

用户购买：商品的业务逻辑。整个业务逻辑由3个微服务提供支持：
仓储服务：对给走的商品扣除仓储数量.
订单服务：根据采购需求创建订单。
帐户服务：从用户帐户中扣除余额.

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

Seata

官网地址：http://seata.io/zh-cn/

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

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

3组件概念

Transaction Coordinator(TC) ：事务协调器，维护全局事务的运行状态，负责协调并驱动全局事务的提交或回滚;
Transaction Manager(TM) ：控制全局事务的边界，负责开启一个全局事务，并最终发起全局提交或全局回滚的决议;
Resource Manager(RM) ：控制分支事务，负责分支注册，状态汇报，并接收事务协调器的指令，驱动分支（本地）事务的提交和回滚；

处理过程

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；
XID 在微服务调用链路的上下文中传播；
RM 向 TC 注册分支事务,将其纳入 XID 对应全局事务的管辖；
TM 向 TC 发起针对 XID 的全局提交或回滚决议；
TC 调度 XID 下管辖的全部分支事务完成提交或回滚请求。

使用

Spring 本地@Transactional

全局@GlobalTransactional

Seata原理

Simple Extensible Autonomous Transaction Architecture,简单可扩展自治事务框架

分布式事务的执行流程

TM开启分布式事务(TM向TC注册全局事务记录)
换业务场景，编排数据库，服务等事务内资源（RM向TC汇报资源准备状态）
TM结束分布式事务，事务一阶段结束（TM通知TC提交/回滚分布式事务）
TC汇总事务信息，决定分布式事务是提交还是回滚
TC通知所有RM提交/回滚资源，事务二阶段结束。

AT模式如何做到对业务的无侵入http://seata.io/zh-cn/docs/overview/what-is-seata.html

在一阶段, Seata会拦截“业务SQL"

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"

执行"业务SQL"更新业务数据，在业务数据更新之后,

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。

二阶段提交：

二阶段若是顺利提交的话，"业务SQL"在一阶段已经提交至数据库，所以Seata框架只需将一阶段的快照数据和行锁删掉，完成数据清理即可。

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。

Seata-Server安装

下载地址：https://github.com/seata/seata/releases/

演示版本：1.3.0

将seata-server-1.3.0.zip解压到指定目录

修改conf目录下的配置文件

备份registry.conf、file.conf两个文件

file.conf

driverClassName = "com.mysql.cj.jdbc.Driver"
url = "jdbc:mysql://127.0.0.1:3306/seata?useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=GMT%2B8"
user = "root"
password = "8520"

registry.conf

创建数据库seata：https://github.com/seata/seata/blob/develop/script/server/db/mysql.sql

-- -------------------------------- 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_gmt_modified_status` (`gmt_modified`, `status`),
    KEY `idx_transaction_id` (`transaction_id`)
) ENGINE = InnoDB
  DEFAULT CHARSET = utf8;

-- 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 = utf8;

-- the table to store lock data
CREATE TABLE IF NOT EXISTS `lock_table`
(
    `row_key`        VARCHAR(128) NOT NULL,
    `xid`            VARCHAR(96),
    `transaction_id` BIGINT,
    `branch_id`      BIGINT       NOT NULL,
    `resource_id`    VARCHAR(256),
    `table_name`     VARCHAR(32),
    `pk`             VARCHAR(36),
    `gmt_create`     DATETIME,
    `gmt_modified`   DATETIME,
    PRIMARY KEY (`row_key`),
    KEY `idx_branch_id` (`branch_id`)
) ENGINE = InnoDB
  DEFAULT CHARSET = utf8;

测试

先启动Nacos端口号8848

再启动seata-server

seata\bin --> seata-server.bat

若启动报Data source rejected establishment of connection, message from server: "Too many connections"

找到mysql的安装目录，打开my.ini文件，找到max_connections配置，默认是100，设置成1000，重启mysql

一定要重新启动MYSQL才能生效

cmd下执行

net stop mysql
net start mysql

订单/库存/账户业务数据库准备

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。

下订单-->扣库存-->减账户（余额）

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。

该操作跨越二三个数据库,有两次远程调用,很明显会有分布式事务问题。

seata_order: 存储订单的数据库

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'
) ENGINE=INNODB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8;
 
SELECT * FROM t_order;

seata_storage:存储库存的数据库

seata_storage库下建t_storage表

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;

seata_account: 存储账户信息的数据库

seata_account库下建t_account表

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;

按照上述3库分别建对应的回滚日志表：https://github.com/seata/seata/blob/develop/script/client/at/db/mysql.sql

-- 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(20)   NOT NULL COMMENT 'branch transaction id',
    `xid`           VARCHAR(100) 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 = utf8 COMMENT ='AT transaction mode undo table';

订单/库存/账户业务微服务准备

seata-order-service2001

建module
写POM

seata版本对应

<?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">
    <parent>
        <artifactId>springcloud2020</artifactId>
        <groupId>com.nuc.springcloud</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

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

    <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>1.3.0</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>8.0.15</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>

</project>

写YML

yml的tx-service-group: mobiw_tx_group与file.conf的vgroupMapping.mobiw_tx_group对应

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: mobiw_tx_group
    nacos:
      discovery:
        server-addr: localhost:8848
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/seata_order?useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=GMT%2B8
    username: root
    password: 8520

feign:
  hystrix:
    enabled: false

logging:
  level:
    io:
      seata: info

mybatis:
  mapperLocations: classpath:mapper/*.xml

file.conf：https://github.com/seata/seata/blob/develop/script/client/conf/file.conf

yml的tx-service-group: mobiw_tx_group与file.conf的vgroupMapping.mobiw_tx_group对应

transport {
  # tcp, unix-domain-socket
  type = "TCP"
  #NIO, NATIVE
  server = "NIO"
  #enable heartbeat
  heartbeat = true
  # the client batch send request enable
  enableClientBatchSendRequest = true
  #thread factory for netty
  threadFactory {
    bossThreadPrefix = "NettyBoss"
    workerThreadPrefix = "NettyServerNIOWorker"
    serverExecutorThread-prefix = "NettyServerBizHandler"
    shareBossWorker = false
    clientSelectorThreadPrefix = "NettyClientSelector"
    clientSelectorThreadSize = 1
    clientWorkerThreadPrefix = "NettyClientWorkerThread"
    # netty boss thread size
    bossThreadSize = 1
    #auto default pin or 8
    workerThreadSize = "default"
  }
  shutdown {
    # when destroy server, wait seconds
    wait = 3
  }
  serialization = "seata"
  compressor = "none"
}
service {
  #transaction service group mapping
  # mobiw_tx_group 与yml指定的一致
  vgroupMapping.mobiw_tx_group = "default"
  #only support when registry.type=file, please don't set multiple addresses
  default.grouplist = "127.0.0.1:8091"
  #degrade, current not support
  enableDegrade = false
  #disable seata
  disableGlobalTransaction = false
}

client {
  rm {
    asyncCommitBufferLimit = 10000
    lock {
      retryInterval = 10
      retryTimes = 30
      retryPolicyBranchRollbackOnConflict = true
    }
    reportRetryCount = 5
    tableMetaCheckEnable = false
    reportSuccessEnable = false
    sagaBranchRegisterEnable = false
  }
  tm {
    commitRetryCount = 5
    rollbackRetryCount = 5
    defaultGlobalTransactionTimeout = 60000
    degradeCheck = false
    degradeCheckPeriod = 2000
    degradeCheckAllowTimes = 10
  }
  undo {
    dataValidation = true
    onlyCareUpdateColumns = true
    logSerialization = "jackson"
    logTable = "undo_log"
  }
  log {
    exceptionRate = 100
  }
}

registry.conf：https://github.com/seata/seata/blob/develop/script/client/conf/registry.conf

registry 使用的是 nacos ， config 使用的是 file

registry {
  # file 、nacos 、eureka、redis、zk、consul、etcd3、sofa、custom
  type = "nacos"
  loadBalance = "RandomLoadBalance"
  loadBalanceVirtualNodes = 10

  nacos {
    application = "seata-server"
    serverAddr = "127.0.0.1:8848"
    group = "SEATA_GROUP"
    namespace = ""
    username = "nacos"
    password = "nacos"
  }
  eureka {
    serviceUrl = "http://localhost:8761/eureka"
    weight = "1"
  }
  redis {
    serverAddr = "localhost:6379"
    db = "0"
    password = ""
    timeout = "0"
  }
  zk {
    serverAddr = "127.0.0.1:2181"
    sessionTimeout = 6000
    connectTimeout = 2000
    username = ""
    password = ""
  }
  consul {
    serverAddr = "127.0.0.1:8500"
  }
  etcd3 {
    serverAddr = "http://localhost:2379"
  }
  sofa {
    serverAddr = "127.0.0.1:9603"
    region = "DEFAULT_ZONE"
    datacenter = "DefaultDataCenter"
    group = "SEATA_GROUP"
    addressWaitTime = "3000"
  }
  file {
    name = "file.conf"
  }
  custom {
    name = ""
  }
}

config {
  # file、nacos 、apollo、zk、consul、etcd3、springCloudConfig、custom
  type = "file"

  nacos {
    serverAddr = "127.0.0.1:8848"
    namespace = ""
    group = "SEATA_GROUP"
    username = ""
    password = ""
  }
  consul {
    serverAddr = "127.0.0.1:8500"
  }
  apollo {
    appId = "seata-server"
    apolloMeta = "http://192.168.1.204:8801"
    namespace = "application"
    apolloAccesskeySecret = ""
  }
  zk {
    serverAddr = "127.0.0.1:2181"
    sessionTimeout = 6000
    connectTimeout = 2000
    username = ""
    password = ""
  }
  etcd3 {
    serverAddr = "http://localhost:2379"
  }
  file {
    name = "file.conf"
  }
  custom {
    name = ""
  }
}

domain

//CommonResult
@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);
    }
}

//订单实体类
@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 OrderDao {

    //1 新建订单
    void create(Order order);

    //2 修改订单状态，从0到1
    void update(@Param("userId") Long userId, @Param("status")Integer status);
}

<?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.nuc.springcloud.dao.OrderDao">

    <resultMap id="BaseResultMap" type="com.nuc.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

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

@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
     * @param order
     */
    @Override
    public void create(Order order) {
        //1. 新建订单
        log.info("----->开始新建订单");
        orderDao.create(order);

        //2. 扣减库存
        log.info("----->订单微服务开始调用库存，做扣减");
        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");
        accountService.decrease(order.getUserId(),order.getMoney());
        log.info("----->订单微服务开始调用账户，做扣减end");


        //4. 修改订单的状态 从0到1   1代表完成
        log.info("----->修改订单状态开始");
        orderDao.update(order.getUserId(),0);
        log.info("----->修改订单状态完成");

        log.info("----->下订单结束了，O(∩_∩)O哈哈~");
    }
}

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

}

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

Controller

@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

@Configuration
@MapperScan({"com.nuc.springcloud.dao"})
public class MyBatisConfig {

}

@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

@EnableDiscoveryClient
@EnableFeignClients
@SpringBootApplication(exclude = DataSourceAutoConfiguration.class)//取消数据源自动创建的配置
public class SeataOrderMainApp2001 {

    public static void main(String[] args) {
        SpringApplication.run(SeataOrderMainApp2001.class, args);
    }
}

seata-storage-service2002

建module
写POM

与2001一致

写YML

与2001相似，修改端口2002、修改数据库seata_storage

file.conf

与2001一致

registry.conf

与2001一致

domain

CommonResult与2001一致

@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;
}

Dao接口及实现

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

<?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.nuc.springcloud.dao.StorageDao">

    <resultMap id="BaseResultMap" type="com.nuc.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_storage
        set used    = used + #{count},
            residue = residue - #{count}
        where product_id = #{productId};
    </update>
</mapper>

Service接口及实现

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);

    @Resource
    private StorageDao storageDao;

    // 扣减库存
    @Override
    public 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");
    }
}

Controller

@RestController
public class StorageController {

    @Autowired
    private 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！");
    }
}

Config配置

与2001一致

主启动

@SpringBootApplication(exclude = DataSourceAutoConfiguration.class)
@EnableDiscoveryClient
@EnableFeignClients
public class SeataStorageMainApp2002 {
    public static void main(String[] args) {
        SpringApplication.run(SeataStorageMainApp2002.class, args);
    }
}

seata-account-service2003

建module
写POM

与2001一致

写YML

与2001相似，修改端口2003、修改数据库seata_account

file.conf

与2001一致

registry.conf

与2001一致

domain

CommonResult与2001一致

@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;
}

Dao接口及实现

@Mapper
public interface AccountDao {

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

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

</mapper>

Service接口及实现

public interface AccountService {

    /**
     * 扣减账户余额
     */
    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);
    
    @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

@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！");
    }
}

Config配置

与2001一致

主启动

@SpringBootApplication(exclude = DataSourceAutoConfiguration.class)
@EnableDiscoveryClient
@EnableFeignClients
public class SeataAccountMainApp2003 {
    public static void main(String[] args) {
        SpringApplication.run(SeataAccountMainApp2003.class, args);
    }
}

测试

数据库初始状态

下单

http://localhost:2001/order/create?userId=1&productId=1&count=10&money=100

查看数据库

超时异常，没加@GlobalTransactional

修改2003

@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");
        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");
    }
}

重启2003再次测试

超时异常，添加@GlobalTransactional

修改2001 OrderServiceImpl

public class OrderServiceImpl implements OrderService {
    @Override
    @GlobalTransactional(name = "mobiw-create-order",rollbackFor = Exception.class)
    public void create(Order order) {...}
}

重启2001，再次测试

没有写入数据库

Seata处理分布式事务

分布式事务问题

Seata

Seata原理

Seata-Server安装

订单/库存/账户业务数据库准备

订单/库存/账户业务微服务准备

seata-order-service2001

seata-storage-service2002

seata-account-service2003

测试

超时异常，没加@GlobalTransactional

超时异常，添加@GlobalTransactional

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