1.业务需求

随着业务需求的变化，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。

制造一个分布式事务问题

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。

《SpringCloud Alibaba 微服务架构》专题(二十二)-Seat处理分布式问题_sql

2.数据库准备

2.1.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。

2.2.初始化业务表

order表

CREATE TABLE `t_order` (
  `id` bigint(11) NOT NULL AUTO_INCREMENT,
  `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',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8;

ALTER TABLE `seata-order`.`order` ADD COLUMN `status` int(1) DEFAULT NULL COMMENT '订单状态：0：创建中；1：已完结' AFTER `money` ;

storage表

CREATE TABLE `t_storage` (
                         `id` bigint(11) NOT NULL AUTO_INCREMENT,
                         `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',
                         PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;

INSERT INTO `seata-storage`.`storage` (`id`, `product_id`, `total`, `used`, `residue`) VALUES ('1', '1', '100', '0', '100');

account表

CREATE TABLE `t_account` (
  `id` bigint(11) NOT NULL AUTO_INCREMENT 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',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;

INSERT INTO `seata-account`.`account` (`id`, `user_id`, `total`, `used`, `residue`) VALUES ('1', '1', '1000', '0', '1000');

创建日志回滚表

使用Seata还需要在每个数据库中创建日志表，建表sql在​​seata-server的/conf/db_undo_log.sql​​​中。
《SpringCloud Alibaba 微服务架构》专题(二十二)-Seat处理分布式问题_sql_02
完整数据库示意图
《SpringCloud Alibaba 微服务架构》专题(二十二)-Seat处理分布式问题_sql_03

3.客户端配置

对seata-order-service、seata-storage-service和seata-account-service三个seata的客户端进行配置，它们配置大致相同，我们下面以seata-order-service的配置为例；

修改application.yml文件，自定义事务组的名称；

spring:
  application:
    name: seata-account-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
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://127.0.0.1:3306/seata_account?useUnicode=true&characterEncoding=utf-8&useSSL=false
    username: root
    password: 123456

添加并修改file.conf配置文件，主要是修改自定义事务组名称；

service {
  #transaction service group mapping
  #修改事务组名称为：fsp_tx_group，和客户端自定义的名称对应
  vgroup_mapping.fsp_tx_group = "default"
  #only support when registry.type=file, please don't set multiple addresses
  default.grouplist = "127.0.0.1:8091"
  #disable seata
  disableGlobalTransaction = false
}

## transaction log store, only used in seata-server
store {
  ## store mode: file、db
  #修改此处将事务信息存储到数据库中
  mode = "db"

  ## file store property
  file {
    ## store location dir
    dir = "sessionStore"
  }

  ## database store property
  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"
    #修改数据库连接地址
    url = "jdbc:mysql://127.0.0.1:3306/seata?useUnicode=true&characterEncoding=utf-8"
    #修改数据库用户名
    user = "root"
    #修改数据库密码
    password = "123456"
  }
}

添加并修改registry.conf配置文件，主要是将注册中心改为eureka；

registry {
  # file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
  type = "eureka"

  nacos {
    serverAddr = "localhost"
    namespace = ""
    cluster = "default"
  }
  eureka {
    serviceUrl = "http://localhost:7001/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"
  }
}

在启动类中取消数据源的自动创建：

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.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.openfeign.EnableFeignClients;

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

创建配置使用Seata对数据源进行代理：

package com.it.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.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;

@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("classpath:mapper/*.xml"));
//        sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources(mapperLocations));
        sqlSessionFactoryBean.setTransactionFactory(new SpringManagedTransactionFactory());
        return sqlSessionFactoryBean.getObject();
    }
}

使用​​@GlobalTransactional​​注解开启分布式事务：

package com.it.servcie.impl;

import com.it.mapper.OrderMapper;
import com.it.pojo.Order;
import com.it.servcie.AccountService;
import com.it.servcie.OrderService;
import com.it.servcie.StorageService;
import io.seata.spring.annotation.GlobalTransactional;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;

@Service
@Slf4j
public class OrderServiceImpl implements OrderService {

    @Resource
    private OrderMapper orderMapper;

    @Resource
    private StorageService storageService;
    
    @Resource
    private AccountService accountService;

    @GlobalTransactional(name = "fsp-create-order",rollbackFor = Exception.class)
    @Override
    public void create(Order order) {

        log.info("-------->开始创建新订单");
        orderMapper.create(order);
        log.info("-------->新订单创建完毕");

        System.out.println(100/0);

        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");

        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");

        log.info("-------修改订单状态");
        orderMapper.update(order.getUserId(),0);
        log.info("-------修改订单状态结束");

        log.info("--------下订单结束了，哈哈哈哈");
    }
}

4.使用到的模块客户端配置

├── seata-order-service -- 整合了seata的订单服务
├── seata-storage-service -- 整合了seata的库存服务
└── seata-account-service -- 整合了seata的账户服务