分布式事务Seata

版本选择

Springboot版本：2.3.x

Nacos版本：1.4.x

Seata版本：1.3.0

MySQL版本：8.0.x

Seata-Server部署

Seata-Server部署包下载：Release v1.3.0 · seata/seata · GitHub

Seata-Server部署脚本下载：https://github.com/seata/seata/tree/1.3.0/script

Seata-Server配置

1）创建数据库实例seata_server，执行seata-server脚本：

-- 查看数据库实例
SHOW DATABASES
-- 创建库存数据库实例
CREATE DATABASE seata_server DEFAULT CHARACTER SET UTF8MB4;

-- -------------------------------- 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;

2）修改部署包seata/conf/registry.conf文件，将注册方式改为nacos，修改内容：

registry {
  # file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
  # type = "file"
  type = "nacos"
  nacos {
    application = "seata-server"
    serverAddr = "127.0.0.1:8848"
    group = "SEATA_GROUP"
    namespace = ""
    cluster = "default"
    username = "nacos"
    password = "nacos"
  }
}

config {
  # file、nacos 、apollo、zk、consul、etcd3
  # type = "file"
  type = "nacos"
  nacos {
    serverAddr = "127.0.0.1:8848"
    namespace = ""
    group = "SEATA_GROUP"
    username = "nacos"
    password = "nacos"
  }
}

3）修改部署包seata/conf/file.conf文件，将存储方式改为db，修改内容：

store {
  ## store mode: file、db、redis
  # mode = "file"
  mode = "db"

  ## database store property
  db {
    ## the implement of javax.sql.DataSource, such as DruidDataSource(druid)/BasicDataSource(dbcp)/HikariDataSource(hikari) etc.
    datasource = "druid"
    ## mysql/oracle/postgresql/h2/oceanbase etc.
    dbType = "mysql"
    # driverClassName = "com.mysql.jdbc.Driver"
    driverClassName = "com.mysql.cj.jdbc.Driver"
    url = "jdbc:mysql://127.0.0.1:3306/seata_server"
    user = "xxxx"
    password = "xxxxxxxx"
    minConn = 5
    maxConn = 30
    globalTable = "global_table"
    branchTable = "branch_table"
    lockTable = "lock_table"
    queryLimit = 100
    maxWait = 5000
  }
}

4）修改seata配置中心为nacos

拷贝/seata/script/config-center/config.txt和/seata/script/config-center/nacos/nacos-config.sh两个文件到部署包seata/目录下。

修改config.txt文件内容：

store.mode=db
store.db.datasource=druid
store.db.dbType=mysql
store.db.driverClassName=com.mysql.cj.jdbc.Driver
store.db.url=jdbc:mysql://127.0.0.1:3306/seata_server?useUnicode=true
store.db.user=xxxx
store.db.password=xxxxxxxx
store.db.minConn=5
store.db.maxConn=30
store.db.globalTable=global_table
store.db.branchTable=branch_table
store.db.queryLimit=100
store.db.lockTable=lock_table
store.db.maxWait=5000

注意：

配置事务分组

service.vgroupMapping.my_test_tx_group=default

• my_test_tx_group：需要与客户端保持一致 ，可以自定义（projectA、projectB…）

（客户端properties配置：spring.cloud.alibaba.seata.tx‐service‐group=my_test_tx_group）

• default：需要跟客户端和registry.conf中registry中的cluster保持一致，default必须要等于registry.conf cluster = "default"。

修改nacos-config.sh文件内容：

将内容：

$(cat $(dirname "$PWD")/config.txt

修改为：

$(cat $(dirname "$PWD")/seata/config.txt

5）进入部署包seata目录，执行脚本：

sh nacos-config.sh ‐h localhost ‐p 8848 -u nacos -w nacos
# 赋权部署包seata目录
chomd 777 .
# 启动seata-server
bin/seata-server.sh -h 127.0.0.1 -p 8091 -m db -n 1

Springboot集成Seata

以库存服务和订单服务为例，每个服务均需添加undo_log表：

-- 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';

库存服务和订单服务均需要添加如下依赖和配置。

添加依赖：

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

添加配置：

seata:
  registry: # 注册中心
    # 配置seata的注册中心, 告诉seata client怎么去访问seata server事务协调器进行通信
    type: nacos
    nacos:
      server-addr: 127.0.0.1:8848   # seata-server所在的注册中心地址
      application: seata-server     # 指定seata-server在注册中心的服务名(默认 seata-server)
      username: nacos
      password: nacos
      group: SEATA_GROUP            # 默认SEATA_GROUP
  config:
    # 配置seata的配置中心，可以读取关于seata client的一些配置，即：seata\seata\script\config-center\config.txt"中的配置
    type: nacos
    nacos: # 配置中心
      server-addr: 127.0.0.1:8848
      username: nacos
      password: nacos
      group: SEATA_GROUP
  tx-service-group: my_test_tx_group

订单服务（被调用者）：

@Transactional(rollbackFor = Exception.class)
@Override
public void insert(){
    log.info("order xid:{}", RootContext.getXID());
    Order order = new Order();
    order.setSku("sku3");
    order.setPurchaseAmount(56);
    order.setOrderStatus(10);
    order.setCreateBy("aaa");
    order.setUpdateBy("ccc");
    orderMapper.insert(order);
}

库存服务（调用者）：

@GlobalTransactional
@Override
public void insert(){
    final String xid = RootContext.getXID();
    log.info("stock xid:{}",xid);
    final ResponseVO<String> insert = orderClient.insert();
    log.info("insert:{},{}",insert.getCode(),insert.getMsg());
    if(insert.getCode() != 200 && insert.getCode() != 0){
        throw new GenericBusinessException(insert.getCode(),insert.getMsg());
    }
    Stock stock = new Stock();
    stock.setSku("sku5");
    stock.setSurplusAmount(66);
    stock.setStockStatus(13);
    Date nowDate = DateUtils.getNow();
    stock.setCreateTime(nowDate);
    stock.setUpdateTime(nowDate);
    stockMapper.insert(stock);
}

其中：orderClient.insert()为Feign接口。

注意：服务出现异常时，不要捕获异常进行处理，否则会出现全局事务异常，即：发生异常时，部分数据提交成功，部分数据处理失败的情况。比如库存减扣成功后调用订单服务创建订单，订单服务发生异常，通过全局异常捕获并将异常信息封装为ResponseVO信息返回给库存服务，此时会出现库存服务执行成功，订单服务执行失败的情况，正确做法是：将异常信息封装为ResponseVO返回给库存服务后，将异常信息封装为自定义异常GenericBusinessException并抛出。