Seata解决分布式事务问题

1、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。

2、Seata简介

2-1、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

2-2、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。

3、Seata-Server安装

3-1、去哪下

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

3-2、怎么玩

  • 本地 @Transactional
  • 全局 @GlobalTransactional

3-3、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

3-4、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

service模块

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service {
  #vgroup->rgroup
  #jcvv_tx_group自定义的
  vgroup_mapping.jcvv_tx_group = "default"
  #only support single node
  default.grouplist = "119.3.211.104:8091"
  #degrade current not support
  enableDegrade = false
  #disable
  disable = false
  #unit ms,s,m,h,d represents milliseconds, seconds, minutes, hours, days, default permanent
  max.commit.retry.timeout = "-1"
  max.rollback.retry.timeout = "-1"
}

store模块

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## transaction log store
store {
  ## store mode: file、db
  mode = "file"
 
  ## 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 = "12345"
    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

修改seata-server-0.9.0\seata\conf目录下的registry.conf配置文件，改用为nacos

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registry {
  # file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
  type = "nacos"
 
  nacos {
    serverAddr = "119.3.211.104:8089"#nginx代理nacos地址
    namespace = ""
    cluster = "default"
  }

linux启动seata

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sh seata-server.sh -p 8091 -h 119.3.211.104 -m file

参考：seata配置各种问题解决办法（周阳老师版）seata setaip不生效橙留香_的博客-CSDN博客

4、Seata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。

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。

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

seata_order库下建t_order表

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USE seata_order;
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;

seata_storage库下建t_storage表

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USE seata_storage;
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 seata_storage.t_storage(`id`, `product_id`, `total`, `used`, `residue`)
VALUES ('1', '1', '100', '0','100');

seata_account库下建t_account表

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USE seata_account;
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=1 DEFAULT CHARSET=utf8;
 
INSERT INTO seata_account.t_account(`id`, `user_id`, `total`, `used`, `residue`)
VALUES ('1', '1', '1000', '0', '1000');

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
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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;

5、Module配置搭建

5-1、Seata之Order-Module配置搭建

cloudalibaba-seata-order2001

pom.xml

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<?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>cloud2020</artifactId>
        <groupId>springcloud</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>
 
    <artifactId>cloudalibaba-seata-order2001</artifactId>
    <dependencies>
        <!-- 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>
        <!-- springcloud alibaba nacos 依赖,Nacos Server 服务注册中心 -->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
 
        <!-- open feign 服务调用 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
 
        <!-- springboot整合Web组件 -->
        <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>
 
        <!-- 持久层支持 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.10</version>
        </dependency>
        <!--mysql-connector-java-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <!--jdbc-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <!-- mybatis -->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
        </dependency>
 
        <!-- 日常通用jar包 -->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency><!-- 引入自己定义的api通用包，可以使用Payment支付Entity -->
            <groupId>com.jcvv.springcloud</groupId>
            <artifactId>cloud-api-common</artifactId>
            <version>${project.version}</version>
        </dependency>
        <dependency>
            <groupId>jakarta.activation</groupId>
            <artifactId>jakarta.activation-api</artifactId>
        </dependency>
    </dependencies>
 
</project>

application.yml

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server:
  port: 2001
spring:
  application:
    name: seata-order-service
  cloud:
    alibaba:
      seata:
        # 自定义事务组，需要和当时在 seata/conf/file.conf 中的一致
        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: 12345
 
feign:
  hystrix:
    enabled: false
 
# 注意，这是自定义的，原来的是mapper_locations
mybatis:
  mapperLocations: classpath:mapper/*.xml
logging:
  level:
    io:
      seata: info

将 seata/conf 下的 file.conf ，registry.conf 移到 rescources 目录下

订单类

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@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;
}

Dao接口及实现

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

OrderMapper.xml

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<?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.jcvv.springcloud.dao.OrderDao">
    <resultMap id="BaseResultMap" type="com.jcvv.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

  • OrderService
    • OrderServiceImpl
  • StorageService
  • AccountService
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public interface OrderService {
    /**
     * 创建订单
     */
    void create(Order order);
 
}
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@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);
}
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@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);
}
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@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->减库存->减余额->改状态
     */
    @Override
    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");
    }
}

controller类

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@RestController
public class OrderController 	{
 
    @Autowired
    private 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!");
    }
}

config类

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@Configuration
@MapperScan("com.jcvv.springcloud.dao") //表明mybatis和dao层相关
public class MyBatisConfig {
}
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package com.jcvv.springcloud.config;

/**
 * @Classname DataSourceProxyConfig
 * @Description chengzhi
 * @Created by chengzhi
 */

import com.alibaba.druid.pool.DruidDataSource;
import io.seata.rm.datasource.DataSourceProxy;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.transaction.SpringManagedTransactionFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import javax.sql.DataSource;
/**
 * 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();
    }

}

主启动类

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@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 SeataOrderMain2001 {
    public static void main(String[] args) {
        SpringApplication.run(SeataOrderMain2001.class,args);
    }
}

5-2、Seata之Storage-Module配置搭建

pom.xml

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<?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>springCloud2023</artifactId>
        <groupId>com.jcvv.springcloud</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>cloudalibaba-storage-service2002</artifactId>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
    <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>
        <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>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </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>
        <dependency>
            <groupId>com.jcvv.springcloud</groupId>
            <artifactId>cloud-api-common</artifactId>
            <version>${project.version}</version>
        </dependency>
    </dependencies>
</project>

application.yml

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server:
  port: 2002

spring:
  application:
    name: seata-storage-service
  cloud:
    alibaba:
      seata:
        tx-service-group: jcvv_tx_group
    nacos:
      discovery:
        server-addr: 119.3.211.104:8089
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://119.3.211.104:3306/seata_storage?useUnicode=true&characterEncoding=utf-8&useSSL=false
    username: root
    password: root

logging:
  level:
    io:
      seata: info

mybatis:
  mapperLocations: classpath:mapper/*.xml

将 seata/conf 下的 file.conf ，registry.conf 移到 rescources 目录下

主启动类

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package com.jcvv.springcloud;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;

/**
 * @Classname SeataStorageMain2002
 * @Description chengzhi
 * @Created by chengzhi
 */
@SpringBootApplication(exclude = DataSourceAutoConfiguration.class)
@EnableDiscoveryClient
@EnableFeignClients
public class SeataStorageMain2002 {
    public static void main(String[] args) {
        SpringApplication.run(SeataStorageMain2002.class, args);
    }
}

库存实体类

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@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

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

StorageMapper.xml

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<?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.jcvv.springcloud.dao.StorageDao">
    <resultMap id="BaseResultMap" type="com.jcvv.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

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

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@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

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package com.jcvv.springcloud.config;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.context.annotation.Configuration;

/**
 * @Classname MyBatisConfig
 * @Description chengzhi
 * @Created by chengzhi
 */
@Configuration
@MapperScan({"com.jcvv.springcloud.dao"})
public class MyBatisConfig {
}


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package com.jcvv.springcloud.config;

import com.alibaba.druid.pool.DruidDataSource;
import io.seata.rm.datasource.DataSourceProxy;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.transaction.SpringManagedTransactionFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;

import javax.sql.DataSource;

/**
 * @Classname DataSourceProxyConfig
 * @Description chengzhi
 * @Created by chengzhi
 */
@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();
    }

}

5-3、Seata之Account-Module配置搭建

pom.xml

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<?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>springCloud2023</artifactId>
        <groupId>com.jcvv.springcloud</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>cloudalibaba-account-service2003</artifactId>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
    <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>
        <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>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </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>
        <dependency>
            <groupId>com.jcvv.springcloud</groupId>
            <artifactId>cloud-api-common</artifactId>
            <version>${project.version}</version>
        </dependency>
    </dependencies>
</project>

application.yml

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server:
  port: 2003
spring:
  application:
    name: seata-account-service
  cloud:
    alibaba:
      seata:
        # 自定义事务组，需要和当时在 seata/conf/file.conf 中的一致
        tx-service-group: jcvv_tx_group
    nacos:
      discovery:
        server-addr: 119.3.211.104:8089
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://119.3.211.104:3306/seata_account?useUnicode=true&characterEncoding=utf-8&useSSL=false
    username: root
    password: root

feign:
  hystrix:
    enabled: false

# 注意，这是自定义的，原来的是mapper_locations
mybatis:
  mapperLocations: classpath:mapper/*.xml
logging:
  level:
    io:
      seata: info

将 seata/conf 下的 file.conf ，registry.conf 移到 rescources 目录下

主启动类

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package com.jcvv.springcloud;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;

/**
 * @Classname SeataAccountMain2003
 * @Description chengzhi
 * @Created by chengzhi
 */
@SpringBootApplication(exclude = DataSourceAutoConfiguration.class)
@EnableDiscoveryClient
@EnableFeignClients
public class SeataAccountMain2003
{
    public static void main(String[] args)
    {
        SpringApplication.run(SeataAccountMain2003.class, args);
    }
}

账号实体类

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@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

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

AccountMapper.xml

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<?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.springcloud.dao.AccountDao">
 
    <resultMap id="BaseResultMap" type="com.atguigu.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

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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);
}
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@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类

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@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

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package com.jcvv.springcloud.config;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.context.annotation.Configuration;

/**
 * @Classname MyBatisConfig
 * @Description chengzhi
 * @Created by chengzhi
 */
@Configuration
@MapperScan({"com.jcvv.springcloud.dao"})
public class MyBatisConfig {
}

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package com.jcvv.springcloud.config;

import com.alibaba.druid.pool.DruidDataSource;
import io.seata.rm.datasource.DataSourceProxy;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.transaction.SpringManagedTransactionFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;

import javax.sql.DataSource;

/**
 * @Classname DataSourceProxyConfig
 * @Description chengzhi
 * @Created by chengzhi
 */
@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();
    }

}

6、Seata之@GlobalTransactional验证

6-1、正常情况演示

下订单 -> 减库存 -> 扣余额 -> 改（订单）状态

启动nacos，seata，及三个微服务

数据库初始情况：

库存表：

订单表：

账户表：

正常下单

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

数据库正常下单后状况：

库存表：

订单表：

账户表：

6-2、超时异常，没加@GlobalTransactional

AccountServiceImpl添加超时

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@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(30); 
        } catch (InterruptedException e) { 
            e.printStackTrace(); 
        }
        accountDao.decrease(userId,money);
        LOGGER.info("------->account-service中扣减账户余额结束");
    }
}

OpenFeign的调用默认时间是1s以内，所以最后会抛异常。

数据库情况：

账户表：

订单表：

库存表：

故障情况

  • 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
  • 而且由于feign的重试机制，账户余额还有可能被多次扣减

6-3、超时异常，加了@GlobalTransactional

用@GlobalTransactional标注OrderServiceImpl的create()方法。

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@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->减库存->减余额->改状态
     */
    @Override
    @GlobalTransactional(name = "fsp-create-order",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");
    }
}

还是模拟AccountServiceImpl添加超时，下单后数据库数据并没有任何改变，记录都添加不进来，达到出异常，数据库回滚的效果。

7、Seata之原理简介

2019年1月份蚂蚁金服和阿里巴巴共同开源的分布式事务解决方案。

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

2020起始，用1.0以后的版本。Alina Gingertail

  • TC (Transaction Coordinator) - 事务协调者
  • TM (Transaction Manager) - 事务管理器
  • RM (Resource Manager) - 资源管理器

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) ;
  • 按业务场景，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

是什么

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。

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。

二阶段提交

二阶段如果顺利提交的话，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。

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。

补充

8、seata遗留错误问题

报错如下：

0101 can not connect to 119.3.211.104:8091 cause:can not register RM,err:can not connect to services-server.

解决方式：

暂无解决，时好时坏