1.基本概念

TM:事務(wù)管理器(開啟總事務(wù)的)
TC:事務(wù)協(xié)調(diào)者(協(xié)調(diào)遠(yuǎn)程服務(wù))
RM:資源管理器(微服務(wù)的事務(wù))
TM--->告訴TC我們要開啟一個(gè)全局事務(wù)--->每個(gè)RM執(zhí)行時(shí)都要向TC注冊一個(gè)分支事務(wù)并實(shí)時(shí)匯報(bào)執(zhí)行狀態(tài)--->
如果有一個(gè)RM失敗,那么TC會(huì)感知到,然后通知其他的RM回滾

2.準(zhǔn)備工作

1.安裝seata服務(wù)器:https://github.com/seata/seata/releases
2.解壓并啟動(dòng)seata服務(wù)器,每個(gè)微服務(wù)都導(dǎo)入registry.conf、file.conf
registry.conf:注冊中心相關(guān)的配置
registry {
  # file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
  type = "nacos" //使用的注冊中心

  nacos {
    serverAddr = "localhost:8848"  //注冊中心地址
    namespace = "public"
    cluster = "default"
  }
}
file.conf:配置信息
service {
  //vgroup->rgroup
  vgroup_mapping.gulimall-ware-fescar-service-group = "default"
  //only support single node
  default.grouplist = "127.0.0.1:8091"
  //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"
}

#使用AT模式(自動(dòng)模式)每個(gè)微服務(wù)都要?jiǎng)?chuàng)建一個(gè)UNDO_LOG表(回滾記錄表)
CREATE TABLE `undo_log` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT 'increment id',
  `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 NOT NULL COMMENT 'create datetime',
  `log_modified` datetime NOT NULL COMMENT 'modify datetime',
  `ext` varchar(100) DEFAULT NULL COMMENT 'reserved field',
  PRIMARY KEY (`id`),
  UNIQUE KEY `ux_undo_log` (`xid`,`branch_id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8 COMMENT='AT transaction mode undo table';

3.整合

<!--依賴-->
<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-seata</artifactId>
</dependency>

#配置使用第一個(gè)或第二個(gè)
spring.cloud.alibaba.seata.tx-service-group=vgroup_mapping.gulimall-order-fescar-service-group
or
file.conf:  vgroup_mapping.gulimall-order-fescar-service-group = "default"

// 配置類:讓seata代理數(shù)據(jù)源
@Configuration
public class MySeataConfig {
    
    @Autowired
    DataSourceProperties dataSourceProperties;//數(shù)據(jù)源屬性

    @Bean
    public DataSource dataSource(DataSourceProperties dataSourceProperties) {

        HikariDataSource dataSource = 
            dataSourceProperties.initializeDataSourceBuilder().type(HikariDataSource.class).build();
        if (StringUtils.hasText(dataSourceProperties.getName())) {
            dataSource.setPoolName(dataSourceProperties.getName());
        }
        return new DataSourceProxy(dataSource);//用代理把原來的數(shù)據(jù)源進(jìn)行包裝
    }
}

//使用
@GlobalTransactional//開啟自動(dòng)配置
@Transactional
@Override
public SubmitOrderResponseVo submitOrder(OrderSubmitVo submitVo) {
}

//seata的AP模式不適用大并發(fā),更適合保存商品信息
//但是超高并發(fā)的情況下,我們不使用seata,為了保證高并發(fā)我們使用:可靠消息+最終一致性